Stimuli Responsive and Multifunctional Polymers: Progress in Materials and Applications
A:KL From Stimuli-responsive Polymers to Self-repairable Materials
M.W. URBAN, Dept. of Materials Science and Engineering, Center for Optical Materials Science and Engineering (COMSET), Clemson University, Clemson, SC, USA
Over the last decade, significant advances in stimuli-responsive materials in general, and polymers in particular, have shown how reversible and irreversible reactions can be utilized to repair mechanically damaged polymer networks. This lecture will focus on the synthesis and design of stimuli-responsive polymer networks that exhibit a wide range of responses, thus offering numerous applications. Various monomers and synthetic approaches have been used to construct stimuli-responsive re-mendable polymer networks. These localized events resulting in nano-, micro- and macrometer scale repairs are driven by orchestrated events facilitated by the formation covalent or supramolecular bonds that parallel segmental mobility and diffusion in damaged areas. Polymer networks that can be repaired by UV/VIS radiation, carbon dioxide and water, and the remote use of oscillating magnetic fields will be highlighted.
Session A-1 - Shape-memory polymers and shape-changing polymers
A-1:IL01 3D Printed Shape-memory Polymer Foams for Biomedical Applications
T.S. WILSON, J.N. RODGRIGUEZ, E.B. DUOSS, J.P. LEWICKI, Lawrence Livermore National Laboratory, Livermore, CA, USA; M.K. HEARON, MIT, Cambridge, MA, USA; D.J. MAITLAND, Texas A&M University, College Station, TX, USA
Shape memory polymers have become one the most researched group of materials for biomedical applications over the last two decades. Their uniquie ability to undergo large strain recovery after placement in vivo makes them excellent candidates for a number of applications in interventional cardiovascular therapeutics. The fabrication of porous SMPs, using processes such as chemical blowing, has been shown by our group to enable novel applications such as aneurysm stabilization. Even more recently, additive manufacturing technologies such as direct ink write, have enabled more complex and controlled device structures. In this presentation we will review the current AM processes for fabrication of architected SMP devices, comment on the polymer chemistry and physical structures required for successful implementation of these processes, and describe ongoing work in our group to develop materials meeting both the requirements for AM processing as well as potential biomedical applications.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
A-1:IL02 Shape Memory of Micro- and Nano-scale Imprinted Patterns on a Supramolecular Polymer Compound
Z. ZHAO, Y.S. CHEN, A. KARIM, R.A. WEISS, Dept. of Polymer Engineering, University of Akron, Akron, OH, USA
Shape memory (SM) polymers can memorize and recover shapes and patterns. Although the majority of work in this field has concerned macroscopic scale shapes, recently work has considered SM patterning on the microscopic and even nanoscopic scale. This talk describes the development and demonstration of SM behavior or micro- and nano-scale patterns imprinted on compounds derived from a supramolecular ionic elastomer (sulfonated EPDM ionomer, SEPDM) and a fatty acid (lauric acid) or a fatty acid salt (zinc stearate). Patterns from a TEM grid (micro-pattern) or a PDMS CD (nano-pattern) were imprinted on a SEPDM-fatty acid (salt) film by heating the film to above the switching point of the SM compound and pressing the template into the polymer sample surface. Good thermal shape memory of both types of samples and a composite sample with a micro-scale and a nano-scale compound was achieved.
This research was funded in part by a grant from the Polymer Division of the National Science Foundation (Grant DMR 1309853).
A-1:IL03 Embolic Applications of Shape Memory Polymer Foams
D.J. MAITLAND, Texas A&M University, College Station, TX, USA
We will present our latest work with thermally activated shape memory polymer (SMP) polyurethane embolic foam devices. Our current focus has been developing devices for cerebrovascular and peripheral occlusion applications. These two types of devices and the engineering challenges that they present will be described. Technical details about the SMP foams will be presented including thermomechanical properties, material degradation and device design and fabrication. Device characteristics including engineering verification testing and in vivo results will also be presented. Finally, the CIMTEC 2016 paper will highlight our most recent work in SMP foam devices: healing pathology of implanted foams, clotting dynamics in the foam, new SMP materials, and modeling SMP devices.
A-1:L05 3D Printed Shape Memory Polymer Biomedical Devices
M. ZAREK, D. COHN, Casali Center of Applied Chemistry, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem, Israel
Shape memory materials have been the subject of academic interest for decades yet it is the rapid progress of the last 15 years which has brought the attention of the field to the top tier academic journals. Nevertheless, there remain significant challenges in fabricating shape memory polymers (SMPs) into complex three-dimensional shapes that have largely limited their penetration into clinical applications. In the case of thermoset SMPs, curing the pre-polymer with a specific, functional geometry is one obvious impediment. Recent advances in both hardware and software for stereolithography 3D printing have opened a promising approach to fabricate 3D shape memory structures. Particularly, 3D printing SMPs into responsive biomedical structures has tremendous potential to transform minimally invasive procedures by drastically expanding the types of devices that can be fabricated with shape memory materials. Our work focuses on developing 3D printed shape memory stents, catheters, and other medical devices that are inaccessible by other processing techniques. To illustrate this technique, we demonstrate the fabrication of SMP devices with semi-crystalline, methacrylated polycaprolactone (MW >10,000 g/mol) and a modified stereolithography printer.
A-1:IL06 Near Infared Driven Polymer Actuators
JENNIFER LU, XINYUAN SHEN, YUZE ZENG, Materials Science and Engineering, University of California at Merced, Merced, CA, USA
We have designed two types of mechanoresponse systems whose conformational changes can be triggered by low-energy stimuli such as near infrared (NIR) or heating a few degrees above room temperature. One incorporates dibenzocyclooctadiene (DBCOD), a flexible cyclooctane group connecting two rigid phenyl rings, into polymer. We have demonstrated polymers that contain a small amount of DBCODs exhibit anomalous giant thermal contraction, with coefficient of thermal expansion up to -2300 ppm/K. Mechanical characterization, calorimetry, spectroscopic analysis and density-functional theory calculations all support that a conformational change of the DBCOD moiety, from the thermodynamic global energy minimum (twist-boat) to a local minimum (chair), is the origin of this abnormally large thermal contraction. We have also fabricated a bilayer structure, i.e., a 1.5 mm-thick NIR mechanoresponsive bottom that is poly(N-isopropylacrylamide) and carbon nanotube composite and an approximately 0.15 mm-thick collagen functionalized cell-seeding top layer that interpenetrates into the bottom layer. We have shown that spatiotemporally controlled mechanical force, generated by NIR stimulation, can be transmitted onto human fetal hepatocytes to induce cell shape change.
A-1:L07 A Thiol-acrylate Main-chain Liquid-crystalline Elastomer Platform for Multifunctional Applications
C.M. YAKACKI, M.O. SAED, A.H. TORBATI, R.H. VOLPE, M.S. BOLLINGER, University of Colorado Denver, Denver, CO, USA; C.P. FRICK, D.R. MERKEL, University of Wyoming, Laramie, WY, USA
Main-chain liquid-crystalline elastomers (LCEs) are a class of stimuli-responsive polymers that demonstrate unique coupling between liquid-crystalline and network order. While these materials are capable of thermo- and photo-reversible actuation, the synthesis of these networks and programming of a permanent monodomain has been a longstanding challenge within the field. This presentation focuses on a new methodology to synthesize, program, and tailor main-chain LCEs by utilizing a two-stage thiol-acrylate Michael addition-photopolymerization reaction. This reaction can be used to homogenously and heterogeneously tailor the transitions in liquid-crystalline order between the polydomain, monodomain, and isotropic states. Due to the facile nature of tailoring the network structure, the influence of crosslinker concentration and functionality is investigated on the thermo-mechanics and thermo-actuation of the networks. Finally, several applications of these materials will be presented ranging from potential biomedical applications, to nano-channel filtration devices, to flexible LCE-based electronics.
A-1:L08 Programmed Anisotropy and Heterogeneity of Porous Liquid Crystal Elastomers
T. WARE, Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, USA
Biological materials derive function from spatial and hierarchical control of structure and composition. In synthetic materials, programmable control of shape, modulus, and porosity is needed to better interface with complex natural tissues. Liquid crystal elastomers are well known to exhibit anisotropic mechanical properties and have been widely studied for the coupling of the nematic director to mechanics. This coupling results in unique behaviors such as soft elasticity and actuation. However until recently, nearly all of these materials have been aligned uniaxially. By directing the self-assembly of liquid crystal elastomers, the highly anisotropic mechanical properties, including thermally induced shape change and elastic modulus, exhibited by these materials can be designed in 2D. These materials can be designed to reversibly change shape with over 50% strain in response heat or solvent. Here we show surface-aligned mixtures of liquid crystal monomers can be further used to spatially align anisotropic micro-porogens, yielding multifunctional, anisotropic foams. The effect of alignment and spatial heterogeneity of porosity on shape change and modulus is explored. These active, designed monoliths may be leveraged in applications such as smart implantable devices.
A-1:L09 Shape Memory Polymers and Stimuli-responsive Methods
YANJU LIU1, JINSONG LENG2, FENGHUA ZHANG2, 1Department of Astronautical Science and Mechanics, Harbin Institute of Technology (HIT), Harbin, P.R. China; 2Centre for Composite Materials and Structures, Harbin Institute of Technology (HIT), Harbin, P.R. China
Shape memory polymers (SMPs) is an interesting field capturing worldwide attention , as they can response to heat, light, microwave, electrical and magnetic field, solution, and the shape, size, strain or stiffness can be changed by a certain external stimulus, exert a tremendous fascination on academics and scientists. This feature broadly expands the opportunity and promotes the activities and investments in this area. The current advances in SMPs are demonstrating the flexible and tunable shape and structure changes and potentials are being combined with new advances of smart applications. A multitude of crucial and novel practical applications are developing in large-scale deployable structures and morphing wings, flexible microelectronic substrates, smart clothes, anti-counterfeiting brands, information carriers, optical devices, biomedical devices. 4D printing as a new fabricating technology possesses the programming and dynamic changing characterizations. SMPs as a kind of active shape-changing and stimuli-responsive materials have seen rapid development, leading the world in growing multiple stimuli, two-way shape memory effect, and variety of stimuli methods, etc. which will offer insight on future direction for upscaling smart wearable and products and applications.
A-1:L10 Laser Assisted 3D Bioprinting of the Magnetic Polymer Nanocomposites Bbased on Nanoparticles FexOy and SrFe12O18 for Medical Applications
I. SHISHKOVSKY1, 2, V. SCHERBAKOV1, Y. MOROZOV2, 1Lebedev Physical Institute (LPI) of Russian Academy of Sciences, Samara branch, Samara, Russia; 2Institute of Structural Macrokinetics and Materials Science (ISMMS), RAS, Chernogolovka, Russia
The high level of a cancer remains one of the most serious medical problems. Majority of currently existing methods of the cancer curing are reduced to the diagnostics and surgical removal of tumors and metastases in combination with chemotherapy or radiation killing the diseased cells. Recently it was demonstrated the potential of the iron oxide nanoparticles and the strontium hexaferrite nanocomposites as functional elements of the nanorobots for interstitial hyperthermia of cancer cells. At present study, the magnetic nanooxides of FexOy type and / or of SrFe12O18 were added to bioresorbable polymer polycaprolactone (PCL) powders for the layer-by-layer selective laser sintering (SLS) of the porous tissue engineering scaffolds. The optimal regimes of magnetic nanocomposite core/ PCL shell structures were determined. Optical and scan electron microscopy with EDX, X-ray diffraction studies show that both core-shell systems have a complex structure with promising electro-physical properties.
A-1:L11 Characterization of Processing-Microstructure-Property Relationships of a Melt-Blown Shape-Memory Polyurethane Nonwoven using Microcomputed Tomography
D.L. SAFRANSKI, K.M. DUPONT, J.C. GRIFFIS, MedShape, Inc., A.S. LIN, R.E. GULDBERG, Georgia Institute of Technology, USA
Shape-memory nonwovens have been proposed as a suitable biomaterial in applications that require controlled forces and tissue in-growth. The objective of this study was to characterize the relationships between processing, microstructure, and shape-memory properties of a melt-blown shape memory polyurethane nonwoven. The microstructure of the nonwoven was systematically varied by changing the air pressure and collector speed, and the thermomechanical properties were then characterized via dynamic mechanical analysis. Decreasing the collector speed decreased the porosity (58-75%), corresponding to an increase in rubbery modulus while increasing the air pressure decreased the fiber diameter (3-10μm). Glass transition temperature (66°C) and free-strain recovery (~75%) were found to be independent of collector speed and air pressure. Recovery stress (0.25-1.5MPa) depended upon the collector speed due to its effect on the rubbery modulus. Microcomputed tomography was used to evaluate changes in microstructure during the shape-memory cycle. Fiber diameter and orientation recovered after activation, but porosity and interfiber spacing were not affected. These results suggest that these nonwovens can be tailored for specific biomedical applications by changing the processing parameters.
Session A-2 - Degradable, stimuli-sensitive polymers
A-2:IL02 Effects of Macromolecular Architecture on the Response of Oxidation-responsive Polymers
R. D'ARCY, N. TIRELLI, University of Manchester, Manchester, UK
We are interested in oxidation as a trigger to perform responsive actions. The rationale is that inflammed tissues most often show an oxidative redox potential, thus oxidation-sensitive materials can open the way to therapies where anti-inflammatory treatments are inherently self-regulated (e.g. drugs released proportionally to the extent of inflammation). Typically, we employ organic polysulfides as oxidation-responsive materials. In this talk, we show how features of the macromolecular architecture (e.g. variations in primary structure, in branching degree) of polysulfides affect the speed and characteristics of their oxidative response.
A-2:L04 Mechanical Characterization of Self-folding Chitosan Film
A. RATH, S. MATHESAN, P. GHOSH, Indian Institute of Technology Madras, Chennai, India
A biomimetic polymer that responds to a stimuli by changing shape and size needs further advancement for applying in various disciplines of science and technology. Cross-linked and particle reinforced chitosan thin film (~ 100 μm), a widely used biopolymer, shows reversible self–folding behavior in contact with water. Folding is due to differential swelling across the thickness of the film. The rate of folding and the maximum extent of folding of the film are primarily affected by the mechanical properties (Young’s modulus, E and hardness, H) and the diffusion characteristics of the film. However, the E and H value of the film is a function of degree of swelling/diffusion, which in turn depends on the interaction of the film with the water. Thus, the E and H value of the film becomes time dependent properties during the process of swelling. In this work, an attempt is made to determine the swelling dependent mechanical properties of the chitosan matrix as a function of time by applying nano-mechanical characterization technique. A molecular dynamic (MD) study is performed to get an insight into the molecular mechanism involved in chitosan–water interaction.
A-2:IL05 Dynamic Covalent Crosslinking in Polymer Networks for Materials-healing
M.B. GORDON, C.J. KLOXIN, Dept. of Materials Science and Engineering, Dept. of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, USA
Covalently crosslinked polymer networks (i.e., thermosets) have a permanent network architecture that makes them particularly well suited for many structural applications but also renders them intractable to post-fabrication manipulation—they cannot be melted, molded, or dissolved. The incorporation of dynamic covalent crosslinks into a polymer network imparts new properties that are associated with both a chemical gel and a weak physical gel [1,2]. Under certain conditions these covalent adaptable networks (CANs) possess the immutable characteristics of a chemical gel; however, once stimulated either via light or heat the covalent bonds become active and the network gains a transient nature characteristics of a weak physical gel. Here, we will present a strategy for incorporating photo-activated reversible bonds, namely a dithiocarbamate iniferter-type structure, within a polymer network for light-triggered network connectivity shuffling . Additional vinyl functionality within the network provides a mechanism for photo-directed materials strengthening, exhibiting a local increase in the modulus by more than two orders of magnitude. This mechanism also enables simultaneous healing and strengthening in fractured materials. Finally, the shape of the elastomer can be manipulated and locked into place via irradiation. Beyond materials healing, this two-tier polymerization strategy can be used in a variety materials applications, from engineering wrinkled topography for lens and sensors to surface functionalization for oleophobic coatings.
 Kloxin, C.J. & Bowman, C.N., “Covalent adaptable networks: smart, reconfigurable and responsive network systems,” Chem. Soc. Rev. 42, 7161-7173, (2013).  Kloxin, C.J., Scott, T.F., Adzima, B.J. & Bowman, C.N., “Covalent adaptable networks (CANS): A unique paradigm in cross-linked polymers,” Macromolecules 43, 2643-2653, (2010).  Gordon, M.B., French, J.M., Wagner, N.J. & Kloxin, C.J., “Dynamic bonds in covalently crosslinked polymer networks for photoactivated strengthening and healing,” Adv. Mater. 42 (2015).
A-2:IL06 Biobased Polymer Systems with Multifunctionality
A. LENDLEIN, Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Teltow, Germany, and University of Potsdam, Potsdam, Germany
In this presentation strategies are introduced to create bio-based polymer systems, in which different material properties and functions can be adjusted almost independently from each other by only small variations in their chemical composition. Polymer network architectures allow modular approaches for the creation of multifunctional polymers on the molecular level. Three dimensional structures of shaped bodies, such as foams or multimaterial systems, offer additional options to implement further functions associated to different hierarchical organization levels. These principles are illustrated by examples such as gelatine-based 3D architectured hydrogels or polymer networks based on different polyester segments. Besides structural functions different shape-memory capabilities, degradability and biofunctionality are considered. Potential applications are discussed ranging from gerontechnology to biomaterial based regenerative therapies and implants for minimally invasive surgery.
A.T. Neffe, A. Lendlein, Adv Healthc Mater 2015, 4, 642. A.T. Neffe et al, Adv Mater 2015, 27, 1738. M.Y. Razzaq, M. Behl, K. Kratz, A. Lendlein, Adv Mater 2013, 25, 5514. M. Saatchi, M. Behl, U. Nöchel, A. Lendlein, Macromol Rapid Comm 2015, 36, 880.
Session A-3 - Stimuli-sensitive gels
A-3:IL01 Stimuli-responsive DNA Hydrogels: Switchable Materials and Interfaces and their Applications
I. WILLNER, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Stimuli-responsive DNA-based hydrogels attract interest as functional materials for controlled drug delivery, sensing, controlled growth of cells, and the design of actuators. Two methods to prepare DNA-based hydrogels were developed: (i) Y-shaped oligonucleotide subunits crosslinked by duplex nucleic acids yield all-DNA hydrogels. (ii) The tethering of oligonucleotides to organic polymer chains, and the use of the nucleic acid tethers as crosslinkers that yield hydrogels. By encoding switchable functional information into the nucleic acid bridging units, cyclic hydrogel-to-solution transitions were demonstrated. Different triggers and counter-triggers, such as DNA-strands/anti-DNA strands, metal ion/ligands, pH-changes, K+-ions/crown ethers or photonic signals, were applied to stimulate the hydrogel-to-solution transitions. By integrating into the bridging units functional information, materials of new properties such as switchable catalytic hydrogels and shape-memory hydrogels were developed. The deposition of DNA hydrogels on surfaces using the hybridization chain reaction (HCR) is a major accomplishment. DNA hydrogels of controlled stiffness, stiffness gradients, and patterned DNA hydrogels, were demonstrated. Applications of the systems will be discussed.
A-3:IL02 Large Cilia Arrays of Multi-responsive Gels: Bulk Properties and Limits to Miniaturization
E. MENDES, P. GLAZER, Dept. of Chemical Engineering, Delft University of Technology, Delft, The Netherlands; H. AN, Eastman, Kingsport, TN, USA
Polymer gels are “wet” materials that are easy to deform when subject to small external mechanical or environmental perturbations. They are also privileged materials to interface the macroscopic world with living matter as they can be rendered biocompatible. Besides passive interfaces, a wide range of actuating gel interfaces can be imagined with various morphologies and also trigged by different mechanisms of sensing or actuation. With this context in mind, we report on the actuation and mechanical properties of macroscopic magnetoresponsive and (biocompatible) electroresponsive gels, investigating their response in bulk and at the micrometer scale. Furthermore, we develop large arrays of microfabricated gel cilia as a concrete example of a multiresponsive gel interface that express sensing and motility (actuation) at the same time. First, we investigate in detail the magneto rheological response of highly swollen polymer gels that contain ferromagnetic particles under external homogeneous magnetic fields. In a second moment, the microfabrication of large array of gel cilia able to respond to pH changes and electric or magnetic fields is demonstrated. The various limitations in the miniaturization of such gel interfaces are also discussed.
A-3:IL03 Design and Applications of Self-folding Hydrogel Micro-structures
D. GRACIAS, Johns Hopkins University, Baltimore, MD, USA
Self-folding broadly refers to a class of self-assembly systems in which structures curve or fold-up either spontaneously or in response to a stimulus. Self-folding can be achieved in hydrogels based on differential swelling derived by structuring bilayers, gradients or patterns of differential cross-linking created with microscale resolution using high resolution photomasks. The design, fabrication and finite element modelling of a variety of precisely patterned, complex 3D shaped hydrogel structures and stimuli responsive actuators such as capsules, helices, polyhedra and grippers will be discussed. In addition, examples of the application of these structures to drug delivery, untethered surgery and soft-robotics will be highlighted. These studies suggest that microscale patterning and manipulation of the geometry and cross-linking of hydrogels can be used to create a wide range of 3D, stimuli responsive hydrogel devices.
A-3:IL04 Injectable and Stimuli-responsive Block Copolymer Hydrogels
DOO SUNG LEE, Theranostic Macromolecules Research Center, School of Chemical Engineering, Sungkyunkwan University, Suwon, Gyeonggi-do, South Korea
Over the last decade, injectable stimuli-sensitive polymeric hydrogels have attracted considerable attention, because of their potential biomedical and pharmaceutical applications, such as in drug/protein delivery and tissue engineering. In this presentation, I will talk about the recent progress in injectable block copolymer hydrogels responding to pH and temperature, which were developed in my group, and their potential biomedical applications. These copolymers usually contain tertiary amine groups as pH-sensitive moieties and many different chemical groups, such as ester, amide, urethane, urea… to control the hydrogel properties, including biodegradable, mechanical, in vitro and in vivo stability, cytotoxicity and release behavior. These copolymer aqueous solutions exists in the sol states at low pH and low temperature with low viscosity, which is suitable for formulation with proteins or bioactive molecules, and exhibited a sol-gel transition to be the gel states with high viscosity by changing to physiological conditions (37 °C, pH 7.4) or after being injected into the body, which can let them serve as proteins/ bioactive molecules depots for long term sustained release. The potential applications of these hydrogels as drugs/proteins carriers will also be reported.
A-3:IL05 Evolution of Self-oscillating Polymer Gels: Functional Control from Nanosize to Bulk Range
R. YOSHIDA, The University of Tokyo, Tokyo, Japan
We developed “self-oscillating” gels that undergo spontaneous cyclic swelling–deswelling changes without any on–off switching of external stimuli, as with heart muscle. The self-oscillating gels were designed by utilizing the Belousov-Zhabotinsky (BZ) reaction, an oscillating reaction, as a chemical model of the TCA cycle. We have systematically studied these polymer gels since they were first reported in 1996 (JACS). Potential applications of the self-oscillating polymers and gels include several kinds of functional material systems, such as biomimetic actuators, mass transport systems and functional fluids. For example, it was demonstrated that an object was autonomously transported in the tubular self-oscillating gel by the peristaltic pumping motion similar to an intestine. Further, self-oscillating polymer brush surface was prepared by SI-ATRP and the dynamic behavior was evaluated. Besides, autonomous viscosity oscillation was realized via metallo-supramolecular terpyridine chemistry, etc. Self-oscillation between unimer/micelle or unimer/vesicle structures was also realized for a synthetic block copolymer. In this presentation, our recent progress on the self-oscillating polymer gels is summarized.
A-3:IL06 Redox Responsive Organometallic Hydrogels as Metal Nanoparticle Foundry
G.J. VANCSO, XUELING FENG, JING SONG*, XIAOFENG SUI, BRAM ZOETEBIER, MARK A. HEMPENIUS, Department of Materials Science and Technology of Polymers, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands; *Institute for Materials Research and Engineering, A*STAR, Singapore
Organometallic macromolecules featuring ferrocene in their main chain show many exciting properties due to the presence of redox responsive iron atoms in their backbone. In this presentation we focus on poly(ferrocenylsilanes) (PFS), which feature main chains consisting of alternating ferrocene and silane units. Substitution of side groups on Si covering a rich range of chemistries allow a variation of the structure and the properties of this polymer. We shall discuss the ability of cationic, as well as anionic PFSs to form (in situ) metal nanoparticles (MNP) by direct reduction of transition metals from their salts without the use of external reducing agents. PFS chains simultaneously stabilize the MNPs following their formation. MNPs have been obtained in various PFS electrolyte solutions as well as in PFS based hydrogels. PFS hydrogel networks with various cross-linkers will be introduced, including PNIPAM links, which provide a dual-responsive hydrogel. When aqueous metal salt solutions swell these hydrogels, ferrocene can reduce the metal ions, depending on the metal’s standard electrode potential. The metal atoms cluster, nucleate, and form crystalline nanoparticles (NP) in the matrix. We discuss hydrogel preparation strategies, and provide structure-property examples for various MNP containing hydrogel nanocomposites including Ag, Au, Pt, Pd, Ir and Rh. We also present examples for antibacterial and electrocatalytic applications.
A-3:IL07 Stimuli-sensitive (Glyco-) Polypeptide Based Polymers and Gels
H. SCHLAAD, University of Potsdam, Institute of Chemistry, Potsdam, Germany; K.-S. KRANNIG, C.D. VACOGNE, Max Planck Institute of Colloids and Interfaces, Colloid Chemistry, Potsdam, Germany
(1) Statistical copolypeptides based on allylglycine and gamma-benzyl-L-glutamate were prepared by ring-opening copolymerization of corresponding N-carboxyanhydrides. The allylglycine units were “click” functionalized with 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose applying thiol-ene photochemistry. Subsequent removal of the acetyl and benzyl protecting groups yielded glycosylated poly(L-glutamate)s, which were capable of recognizing proteins (specific carbohydrate-lectin interactions) and changing solution properties (ionization and conformation) in dependence of solution pH.
(2) Poly(gamma-benzyl-L-glutamate-co-allylglycine) formed organogels at < 2% w/v in toluene, tetrahydrofuran, or 1,4-dioxane, assisted by UV-crosslinking with dithiol. Debenzylation of dioxane gels yielded and highly absorbent and pH-responsive poly(L-glutamate) hydrogels, which are attractive materials for biomedical applications.
A-3:L08 Nanoparticles and Hydrogels from Thermoresposive Self-assembly of Fluorinated Oligo(Ethylene Glycol) Methacrylate-based Copolymers
F. ZUPPARDI, F. R. CHIACCHIO, R. SAMMARCO, M. MALINCONICO, G. GOMEZ D’AYALA, P. CERRUTI, Institute for Polymers, Composites and Biomaterials (IPCB-CNR), Pozzuoli (NA), Italy
LCST and particle size of self-assemblying oligo(ethylene glycol) methacrylate (OEGMA) and pentafluorostyrene (PFS) copolymers can be precisely tuned by varying monomer molar ratio. Water-soluble copolymers were synthesized at different molar ratios via free radical polymerization. The self-assembly of thermo-responsive copolymers in water was studied in detail by dynamic light scattering (DLS), 1H NMR, simultaneous rheometry-FTIR spectroscopy, and transmission electronic microscopy (TEM). All copolymers exhibited sharp and reversible LCST. Above the LCST, copolymers with higher OEGMA content form micron-sized and hydrated particles, resulting in a pseudo-hydrogel structure. When the hydrophobic character increases, a more significant dehydration of OEGMA side chains leads to a strengthening of polymer chain interactions, resulting in the formation of nanosized and phase-segregated particles.
Furthermore, the amphiphilic copolymers were employed to develop different thermo-responsive platforms for drug release. In particular, stable gels and nanoparticles were prepared by copolymer crosslinking through reaction between a diamine (cross-linker agent) and pentafluorostyrene moieties.
Session A-4 - Multifunctional (Nano)composites and Multi-material Systems
A-4:IL01 Bio-inspired Design of Organic-inorganic Nanocomposites for Applications in Regenerative Medicine
R. NEJADNIK, H. WANG, M. DIBA, S.C.G. LEEUWENBURGH, Radboud University Medical Center, Department of Biomaterials, Nijmegen, The Netherlands
Biomaterials are now increasingly considered as bioactive scaffolds with the capacity to orchestrate cellular behavior and induce tissue regeneration. Calcium phosphate ceramics possess the inherent capacity to stimulate bone tissue regeneration, which has resulted into widespread use of these bioceramics in orthopedics and dentistry. Calcium phosphate nanoparticles have been incorporated into organic matrices for several decades, but the emergence of nanotechnology has accelerated progress in the development of organic-inorganic nanocomposites which mimic the complex nanostructure of bone tissue. This presentation will focus on novel strategies to mineralize organic matrices. Specific attention will be paid to the functionalization of organic matrices with calcium-binding moieties to facilitate the formation of non-covalent bonds between organic matrices and calcium phosphate nanoparticles, thereby improving their mechanical and self-healing properties.
A-4:L02 Light and Heat Induced Patterning of Silver Nanoparticle/Polymer Nanocomposites
J. MARQUES-HUESO, D.E. WATSON, M.P.Y. DESMULLIEZ, Heriot-Watt University, School of Engineering & Physical Sciences (EPS), Institute of Signals, Sensors and Systems, Microsystems Engineering Centre (MISEC), Edinburgh, Scotland, UK
Silver nanoparticles have many different applications due to their particular properties. Their plasmonic behaviour can be exploited for optical components such as light absorbers, filters, or colorimetric sensors, among others. The enhanced reactivity of the nanoparticles can also be used for applications, such as catalysis, precursors for other processes or anti-bacteriological action. The control on the positioning and patterning of NPs arrays are requisites to enable some of these applications. We present here a new synthesis of silver nanoparticle patterns. Some of the most commonly used thermoplastics have been used here as host in order to induce the nanoparticle synthesis. This provides a route for patterning the nanocomposites in heat-induced manufacturing processes. Moreover, the use of photo-sensitizers has allowed the selective synthesis of the nanoparticles with micrometric resolution by the use of light, which provides a precise method for the positioning of nanoparticles on surfaces.
A-4:L03 Spatiotemporal Control of Self-oscillating Gel by Uniformly Aligned Inorganic Nano Sheets
YOUN SOO KIM1, Y. ISHIDA2, Y. EBINA3, T. SASAKI3, R. YOSHIDA1, T. AIDA1, 1School of Engineering, The University of Tokyo, Tokyo, Japan; 2RIKEN Center for Emergent Matter Science, Saitama, Japan; 3National Institute for Materials Science, International Center for Materials Nanoarchitectonics, Tsukuba, Ibaraki, Japan
For the development of muscle-like actuators, the most promising materials are stimuli-responsive hydrogels that exhibit abrupt volume change in response to on–off switching of external stimuli. In contrast, Yoshida et al. have developed a novel “self-oscillating” gel that exhibits an autonomous mechanical swelling–deswelling oscillation without any on–off switching of external stimuli. The basic chemical structure of the self-oscillating polymer is a copolymer of N-isopropylacrylamide (NIPAAm) and Ru(bpy)3 as a catalyst for the Belousov–Zhabotinsky(BZ) reaction. In response to the redox change of Ru(bpy)3 units, hydrophilicity and LCST of gel matrices change, which causes the swelling and deswelling of the gel networks. Unilamellar titania nanosheet (TiNS) is quite attractive, owing to its highly anisotropic shape and unique magnetic properties, where TiNSs in an aqueous dispersion magnetically align cofacially. Through in-situ polymerization, the aligned structure of TiNSs can be chemically locked in the hydrogel network. Based on this strategy, we fabricated an anisotropic self-oscillating hydrogel by hybridization of polyNIPAAm and Ru(bpy)3 units with uniformly aligned TiNSs. The as-prepared hydrogel showed autonomous anisotropic deformation driven by BZ reaction.
A-4:IL04 New Developments in Advanced Polybenzoxazine Thermosets and Related Nanocomposites
L. DUMAS, L. BONNAUD, M. POORTEMAN, M. OLIVIER, PH. DUBOIS, Materia Nova Research Center & University of Mons UMONS, Mons, Belgium
Polybenzoxazines are currently raising huge interest in the field of materials science and more particularly as thermosetting materials and related (nano)composite materials. Based on a remarkable balance of material properties, combining both the specific advantages of traditional epoxy and phenolic resins, polybenzoxazines appear as unique candidates for the production of high-performance materials, particularly when they are filled with nanoparticles like carbon nanotubes for instance. This contribution aims at investigating recent developments and trends in the field of advanced polybenzoxazine-based thermosetting resins, including Bio-based polybenzoxazine nanocomposites. Interestingly enough, high performance polybenzoxazine/multi-wall carbon nanotube nanocomposites have been synthesized as well, displaying unexpected thermal and physical properties, particularly when applied as nanocoatings for metallic substrates.
A-4:IL05 Nanobiomaterials Enabling Low Dose Bioimaging Diagnosis and Stem Cell Therapies of Vascular Disease
HYUNJOON KONG, Chemical & Biomolecular Engineering/Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
Vascular networks in human bodies play pivotal roles to transport oxygen, nutrients, and hormones to and from cells residing in tissues and organs. Due to several reasons, these vascular networks encounter occlusion, leakage, or rupture, thus becoming dysfunctional. The resulting cardiovascular disease is the world’s leading cause of death. Extensive efforts were made to detect these vascular diseases at early stage using nanocarriers of imaging contrast agents and bioactive molecules. Despite some impressive results to dates, there are still great demands to improve quality of diagnosis while reducing dose of contrast agents. To this end, we have been studying and engineering effects of spatial organization of contrast agents on and within nanocarriers, in order to translate the results into preclinical imaging of vascular defects. In this talk, I will introduce a few nanocarriers enabling low dose vascular imaging. These include (1) a gadolinium-coated liposome and (2) superparamagnetic iron oxide nanoparticle clusters, two of which were designed to enhance quality of magnetic resonance imaging (MRI) for leaky vasculature, while reducing their doses by one order of magnitude. Then, I will briefly depict a method to regulate cell transports for vascular therapies.
A-4:L06 Green Source Based Carbon Nano Rods for Developing the Quantum Resistive Vapor Sensors to Detect Cancer Biomarkers
A. SACHAN, K.M. TRIPATHI, M. CASTRO, J.F. FELLER, Smart Plastics Group, European University of Brittany (UEB), LIMATB-UBS, Lorient, France; V. CHOUDHARY, Centre for Polymer Science & Engineering, Indian Institute of Technology, Delhi, India
Since last decades fabrication of convenient, green, rapid and cost effective system for the detection of toxic VOCs with high sensitivity is turned into a cutting edge research due to various potential applications in medical diagnosis, environmental monitoring, food quality control and homeland security. Detection of cancer biomarkers via nano material based sensors has emerged as a fast growing research area. This detection technique of exhaled breath is very rapid, easy and inexpensive. Most of these VOCs include alkanes, alcohols, ketones and benzene derivatives, therefore to bring some selectivity in the sensors is an important aspect of fabrication. In the present study carbon rods (CNRs) prepared from natural source as such and dispersed in PLA and PVA matrices are used as sensor array for the VOCs. CNRs were fabricated in a simple, fast and green way from organic precursor by using traditional pyrolysis method. These CNRs are completely free from any metallic contaminants. The potential application of carbon nano rods and its nanocomposite with PLA/PVA as sensor for toxic VOC in particular, acetone, water, methanol, ethanol and hexane-1 is demonstrated.
A-4:L07 Effects of External Magnetic Field on Polymeric Foam-ferromagnet Composites
M. D'AURIA1, 2, V. VOLPE3, D. DAVINO2, R. PANTANI3, L. SORRENTINO1, 1Istituto per i Polimeri, Compositi e Biomateriali, Consiglio Nazionale delle Ricerche, Portici (NA), Italy; 2Dipartimento di Ingegneria, Università degli Studi del Sannio, Benevento, Italy; 3Dipartimento di Ingegneria Industriale, Università di Salerno, Fisciano (SA), Italy
Composite lightweight materials based on a polymeric matrix with embedded magnetic micro-particles have been developed. The application of a magnetic field (MF) during the foaming of samples induced the alignment of magnetic particles along the MF lines, forming reinforcing chain-like structures. The presence of aligned micro-particles imparted an anisotropic mechanical behavior along the particle alignment direction, thus strongly improving mechanical stiffness and strength compared to randomly filled systems. The application of a MF on pre-strained samples during the magneto-mechanical characterization resulted in a direct relationship between the measured variation of the elastic modulus of the foam and the time dependent intensity of the applied MF (also at low magnetic field strength, below 200 kA/m). In particular, all reinforced samples pre-strained in the linear elastic region of the stress-strain curve exhibited a magneto-strictive response (negative variation of the measured stress). Instead, a positive variation of the measured stress (strengthening effect) was only detected in samples with aligned particles at pre-strains above the yield point. This behavior has been related to the tendency of chain-like aggregates in buckled cell edges to re-align along the MF lines.
A-4:IL09 3-D Templates for Hierarchical Device Structures
J.J. WATKINS, University of Massachsuetts, Amherst, MA, USA
We have outlined templating strategies for electronic and optical device fabrication that include self-assembly of well-ordered polymer/nanoparticle hybrids and nanoimprint lithography using novel materials sets that enable the direct fabrication of patterned functional device layers. Using additive-driven self-assembly, for example, we demonstrate the formation of periodic nanocomposites with tunable magnetic and optical characteristics containing up to 70 wt. % of metal, metal oxide and/or semiconducting nanoparticles through phase specific interactions of the particles with the block copolymer templates. We have further developed highly filled nanoparticle/polymer hybrids for applications that require tailored dielectric constant or refractive index and a new imprinting process that allows direct printing of patterned 2-D and 3-D crystalline metal oxide films and composites with feature sizes of less than 100 nm. Applications in flexible electronics, light and energy management, and sensors and will be discussed.
Session A-5 - Multifunctional Surfaces
A-5:IL01 Block Copolymers at Interfaces – Statics, Kinetics and Rheology
L. LAUFER, M. ARMON, M. GOTTLIEB, Chemical Engineering Department, Ben Gurion University, Beer Sheva, Israel
Amphiphilic block copolymers have been recognized as effective surface active molecules with with multitude of industrial and medical applications. Yet, the relation between the molecular architecture, size and chemistry is not clear. Fundamental understanding of these simpler molecules may provide the tools for understanding interfacial behavior of structurally more complex biopolymers. Adding functionalities to these molecules widens the range of possible applications and responsiveness of the molecules to environmental conditions.
In this study, we examined a series of polyethyleneoxide –b-polydimethylsiloxane (PEO-PDMS) diblock copolymers and PEO-PDMS-PEO triblock copolymers at different interfaces. These highly amphiphilic copolymers show some remarkable features.
Results will be discussed in terms of the effects of architecture (diblock vs. triblock), chain length, block size and block size ratio (A/B) on interfacial properties, dynamics and rheology.
A-5:L02 Self-healing Fluoropolymer Brushes as Anti-fouling Coatings
ZHANHUA WANG, H. ZUILHOF, Wageningen University, Wageningen, The Netherlands
Fluoropolymer brushes, often in combination with surface structuring, are widely used to prevent nonspecific adsorption of polymeric or biological material on sensor and microfluidic surfaces. Here we present a 75 nm thick fluoropolymer brush that is covalently bound onto flat or nanostructured silicon surfaces, and which displays excellent self-healing and anti-fouling property. The fouling by a wide range of organic polymers of even flat brush-coated surfaces is reduced up to 99%. This strong reduction can also be repaired, even more than 10 times, after the polymer brush has been damaged. This repair hinges on the self-healing character of these brushes via molecular reorganization at the surface-air interface at slightly elevated temperatures. In this study we investigate the influence of thickness, molecular architecture and degree of fluorination of the polymer brush on the anti-fouling property and self-repair properties. Finally, these features can be combined with nanostructuring of the Si surface. Upon using such simply-applied structuring, the antifouling properties even improve further, and the reasons behind that will be discussed. In addition, these brushes also displayed excellent anti-biofouling character as shown in a series of protein adhesion studies.
A-5:L04 Smart Surfaces for Directing Nanoparticle Formation
N. YONET-TANYERI, Department of Biomedical Engineering, Istanbul Medipol University, Istanbul, Turkey; P.V. BRAUN, Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
Advancements in the fabrication techniques have enabled researchers to design&develop materials that are composed of nanoparticles embedded in the matrices.Such composite materials show unique electronic, magnetic, and optical characteristics that can be used in various applications.However, one of the greatest challenges that remained unresolved in the fabrication process is the generation of spatio-temporal control over nanoparticle dispersion, e.g. ordered arrays of nanoparticles, within matrix.Here in this work, we have demonstrated the design of a molecular device that is capable of generating spatio-temporally controlled surface decoration of the polymer thin films with nanoparticles.Previously, we've developed a molecular device that can direct motion of small molecules (fluorophores) on a flat surface.Directed molecular transport was provided by diffusion of the molecule of interest along the patterns of functional polymer thin films, namely polymer brushes.The microfluidic channel in the device served as the reservoir for the diffusing species.Our ultimate goal is to design such molecular devices that can generate spatio-temporally controlled surface nanoreactions like reduction of metal ions by guiding diffusive transport of multiple reactive ionic species.
A-5:IL05 Interplay of Morphology and Degradation in Two-dimensional Polymer Films at the Air-water Interface
B. SCHULZ, A.-C. SCHOENE, A. LENDLEIN, University of Potsdam, Institute of Chemistry, Potsdam, Germany; and Institute Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Teltow, Germany
Biodegradable polymers are of high significance for clinical applications and consequently predictions of their short- and long-term degradation are demanded. The interactions occurring at the interface between the biological system and the material determine the fate of an implant and in this way are of paramount importance for the success of a clinical application. The Langmuir techniques allow the precise formation of films from multi-component systems with defined super molecular architectures and geometries from the nanometer up to micrometer scale. The compression of polymer films at the air-water interface mimics the mechanical behavior of the biomaterial surface under specific circumstances close to the real biological environment. For clinically relevant (co)polyesters, namely poly(ε-caprolactone) PCL, poly[(rac-lactide)-co-glycolide] PLGA, the mechanically induced crystallization by surface pressure or aggregation processes are discussed. The influence of structural parameters such as type of repeating unit, sequence structure and layer morphology on degradation rate and behavior will be illustrated. The knowledge gained in these studies might stimulate the design of a next generation of degradable polymers.
A-5:L06 Optically Tunable Mechanical and Functional Properties of Azo-polymer Thin Films
F. FABBRI1, L. SORELLI2, D.-V. AHN3, J. FRECH-BARONET2, M. FAFARD2, Y. LASSAILLY3, K. LAHIL3, L. MARTINELLI3, T. GACOIN3, J. PERETTI3, 1Institut d'Electronique Fondamentale, Université Paris-Sud/CNRS, Orsay, France; 2Département de Génie Civil, Université Laval, Québec, Canada; 3Laboratoire de Physique de la Matière Condensée, Ecole Polytechnique/CNRS, Palaiseau, France
Thin film materials containing azobenzene derivatives present remarkable photomechanical responses to light stimuli. When grafted into solid-state matrices, the azobenzene molecules’ photo-isomerization can produce a change in both the morphology and in the mechanical properties of the host matrix. In this work, we study both these aspects by coupled shear-force/SNOM microscopy techniques, which give access to the photodeformation kinetics and to the light field distribution in-situ, in real-time and at nanoscale and by instrumented nanoindentation, which allows to quantitatively measure the material mechanical properties. We exploit the azo-materials photo-induced deformation processes to elaborate stacked hybrid gold/dielectric micro/nanostructured systems, whose sub-micron patterns exhibit specific optical and plasmonic properties that can be tuned by the light stimuli. Nanoprobes are also used to locally influence the photomechanical processes, thus achieving complex light-assisted nanostructuration. The mechanical properties of the azo-materials can also be tuned by light. In particular, we show that the photoinduced changes in their viscoelastic/viscoplastic behavior strongly depend on the illumination configuration, on the nature of the matrix and on the azo-film thickness.
Session A-6 - Multifunctional Polymer Systems for Energy Storage and Flexible Electronics
A-6:IL01 Carbon Nanotube Fibre Microelectrodes
P. POULIN, Centre de Recherche Paul Pascal - CNRS Université de Bordeaux, Pessac, France
We present fiber microelectrodes which are made of assembled carbon nanotubes (CNTs). The present fibers are highly porous and of a few microns in diameter. They exhibit promising performances as electrodes for bio-fuel cells (BFCs) or electromechanical actuators. The microelectrodes are made by a one-step wet fiber spinning process in which CNTs and bilirubin oxidase (BOD) are combined without any red-ox mediator or binder. BOD allows the reduction of oxygen at potentials suitable for uses in physiological conditions. Moreover, because of their small dimensions and electronic properties, CNT microelectrodes overcome poor electron transfer and slow mass transport limitations. In addition to applications in BFCs, CNT fibers can be used as miniaturized electromechanical actuators. Indeed, CNT assemblies deform in response to charge injection and electrostatic phenomena. Microfibers perform better than random assemblies of CNTs. Nevertheless, as observed in other CNT based actuators, raw CNT fibers suffer from stress relaxation due to the sliding of neighboring CNTs. In order to overcome this limitation, we have developed a modified fiber spinning process in which a small amount of polymer binder is included within the fibers during the spinning process. The presence of the binder results in a significant reduction of stress relaxation. From a general point of view, the present results open routes towards the use of CNT microelectrodes to power or actuate implanted biomedical micro-devices.
A-6:IL03 Soft Matter Containing Ionic Liquid as Solvent
MASAYOSHI WATANABE, Yokohama National University Yokohama, Japan
We have proposed soft matter containing ionic liquid (ion gels). Ion gels are composed of ionic liquids (ILs) immobilized within a three-dimensional molecular network. Such gels preserve the attractive physicochemical properties of ILs, such as nonvolatility, thermal stability, electrochemical stability, and high ionic conductivity, while maintaining a soft solid consistency. Ion gels are a novel platform for many applications such as electrolyte membranes, actuators, gas-separation membranes, and organic thin-film transistors. We present here the reversible micellization and sol-gel transition of photo-responsive ABA block copolymer solutions in an ionic liquid (IL) triggered by a photostimulus. Such sol-gel transition has been utilized to design photo-healable materials. Damaged part of materials is UV-irradiated to convert gel to sol, followed by irradiated by visible light in order to convert again sol to gel. By this procedure, the damaged part was demonstrated to be healed to the original state.
A-6:L04 Electroactive Polymer Based Conducting, Magnetic, and Luminescent Triple Composites
A.V. KUKHTA, A.G. PADDUBSKAYA, P.P. KUZHIR, S.A. MAKSIMENKO, Research Institute for Nuclear Problems, Belarusian State University, Minsk, Belarus; S.A. VOROBYOVA, Research Institute for Physical and Chemical Problems, Belarusian State University, Minsk, Belarus; S. BELLUCCI, National Institute of Nuclear Physics, Frascati National Laboratory, Frascati, Italy; P.K. KHANNA, Defense Institute of Advanced Technology, Deemed University, Pune, India
Organic-inorganic composites based on polymer and inorganic nanofiller are attractive for manifold applications in flexible electronic devices during the last decade. Multi-component hybrid materials give the possibility to result in the development of well conducting polymer composites with new attractive properties. One of the approaches is the decoration of carbon nanomaterials with metallic conducting, magnetic, and luminescent nanomaterials. The combination of these materials with polymers gives triple conducting composites with different properties. We showed that application of triple nanocomposite based on PEDOT:PSS and graphene nanoplatelets (GNP) decorated with Cu nanoparticles, results in further conductivity increase as compared to pure GNP addition, without essential transparency decrease. The decoration of GNP with Fe3O4 nanoparticles gives composite films with magnetic properties and strongly increased surface. Strong luminescent quenching is usually observed in nanocarbon containing materials. However, we have found luminescent system with 30% luminescence quenching only. As a result, we obtained highly conducting luminescent triple composite. The prospects of our future studies and possible applications are discussed.
Session A-7 - Pharmaceutical and Medical Applications of Smart Polymers
A-7:IL02 Medical Applications of Nature-inspired Adhesive Polymers
HAESHIN LEE, Department of Chemistry, Korea Advanced Institute of Science & Technology, South Korea
Catecholamines are found ubiquitously in nature. Wetting-resistant, adhesive foot-pads in mussels, neurotransmitters in the brain, melanin bio-pigments in the skin and eyes, squid beaks, and insect cuticles are related examples. In materials science, catecholamines have recently attracted significant attentions due to unprecedented material-independent surface-functionalization properties found in poly(dopamine) (pDA) and poly(norepinephrine). These two catecholamines of dopamine and norepinephrine are in situ polymerized being poly(dopamine) and poly(norepinephrine) in aqueous solutions, exhibiting excellent coating properties with a thickness from a few to ~ 50 nm. Unlike the coating properties, catechol-conjugated polyamine such as chitosan-catechol shows tissue adhesive properties similar to the water-resistant adhesion found in marine mussels. Oxidation of catechol generates amine-reactive catecholquinone conjugated chitosan, which performs inter-molecular reactions to be chitosan hydrogels. In my talk, various aspects of chitosan-catechol i) catalyst-mediated yet catalyst-free hydrogel, ii) vanadium-catalyzed chitosan hydrogel, and iii) transparent chitosan-catechol film will be presented.
A-7:L04 Cold Plasma Reticulation of Shape Memory Polymer Embolic Tissue Scaffolds
L.D. NASH, N.C. RIVERA, K.P. EZELL, J.K. CARROW, S.M. HASAN, A.K. GAHARWAR, D.J. MAITLAND, Texas A&M University, College Station, TX, USA
Shape memory polymer (SMP) foams have shown promise as effective embolic materials and have the potential to address limitations of current embolization techniques by reducing the number of devices necessary for treatment and improving long term healing outcomes. However, gas blown SMP foams inherently have membranes between pores, which can lead to limited performance as tissue scaffolds. Reticulation, or the removal of membranes between adjacent foam pores, is advantageous for improving device performance through increased blood permeability and cellular infiltration. This work characterizes the effects of cold gas plasma reticulation processes on bulk polyurethane SMP films and SMP foam geometries relevant to a peripheral vessel embolization device. Plasma induced changes on material properties were characterized using atomic force microscopy, x-ray photoelectron spectroscopy, in vitro cytocompatibility, scanning electron microscopy, and goniometry. Device specific performance was characterized using free strain recovery experiments and permeability measurements. Overall, these plasma reticulated SMP foams show promise as embolic tissue scaffolds due to increased surface cytocompatibility and increased bulk permeability.
A-7:L05 A Bioactive “Self-fitting” Shape Memory Polymer (SMP) Scaffold to Treat Craniomaxillofacial (CMF) Bone Defects
M.A. GRUNLAN1, 2, DAWEI ZHANG1, M.S. HAHN3, J.E. MARINO3, 1Texas A&M University, Department of Biomedical Engineering, 2Texas A&M University, Department of Materials Science and Engineering, 3Rensselaer Polytechnic Institute, Department of Biomedical Engineering, College Station, TX, USA
Scaffold properties are essential to maximize healing of critical-sized craniomaxillofacial (CMF) bone defects. Regeneration would be enhanced by scaffolds that can precisely match the irregular boundaries of bone defects as well as exhibit an interconnected pore morphology and bioactivity. In this work, a shape memory polymer (SMP) scaffold was developed exhibiting an open porous structure and the capacity to conformally “self-fit” into irregular defects. The SMP scaffold was prepared via photocrosslinking of poly(ε-caprolactone) (PCL) diacrylate using a solvent casting/particulate leaching (SCPL) method with a fused salt template and coated with polydopamine. Following exposure to warm saline (T > Ttrans where Ttrans = Tm of PCL), the scaffold became malleable and could be pressed into an irregular model defect. Subsequent cooling caused the scaffold to lock in its temporary shape within the defect. Polydopamine-coated scaffolds exhibited superior bioactivity (i.e. hydroxyapatite formation), osteoblast adhesion, proliferation, osteogenic gene expression and ECM deposition. In addition, polydopamine-coated scaffolds induced significantly higher expression of bone-related protein by h-MSCs relative to uncoated scaffolds even without osteogenic media supplements.
A:P02 The Reversible Shape-memory Behavior of Crosslinked Poly(e-caprolactone) under Stress and Stress-free Conditions
O. DOLYNCHUK, Leibniz-Institut für Polymerforschung Dresden e.V., Dresden, Germany; I. KOLESOV, Martin Luther University Halle-Wittenberg, Center of Engineering Sciences, Hale (Saale), Germany, Polymer Service GmbH Merseburg, Merseburg, Germany; D. JEHNICHEN, Leibniz-Institut für Polymerforschung Dresden e.V., Dresden, Germany; H.-J. RADUSCH, Polymer Service GmbH Merseburg, Merseburg, Germany
Polymeric materials revealing reversible shape-memory effects (SMEs) are in focus due to fundamental interest of underlying molecular mechanisms and various applications as sensors and actuators. Poly(ε-caprolactone) (PCL) attracts particular attention in this regard because of its excellent biocompatible and biodegradable properties. The present work discloses the effect of crosslink density on the reversible SME under constant load in PCL. Moreover, thermal properties of the samples as well as morphology and orientation of the crystalline structure formed under load in covalent networks of PCL were compared with those in undeformed PCL. The received results showed a significant rise of crystallinity and crystal thickness after application of a constant load. The theoretical predictions of crystallinity, type of crystalline structure as well as size and orientation of the crystals got by modeling the reversible SME in PCL well correspond to those obtained experimentally. A remarkable reversible SME under stress-free and programming-free conditions was observed in PCL with the highest achieved crosslink density. The study of the crystalline structure formed during this effect confirmed that oriented crystallization is an origin of the phenomenon.
A:P05 Nanocomposites Spray Quantum Resisitve Sensors (sQRS) for Structural Health Monitoring of Composite Wind Blades
A. LEMARTINEL, M. CASTRO, J.F. FELLER, Smart Plastics Group, Université Européenne of Bretagne (UEB), LIMATB-UBS, Lorient, France; J. DE LUCA, Institut de Recherche Technologique Jules Verne, Bouguenais, France
The growing development of renewable energies causes the fabrication of larger composite’s pieces. These structures may also be submitted to more severe environmental conditions. The estimation of damages and the prediction of the part maintenance through an optimized health monitoring procedure is therefore a key point. The Smart Plastics group is developing nanocomposites sQRS able to monitor strain and damage accumulation in composite structures1. These sensors can be either deposited on the surface or embedded in the composite part during its production2. Due to their small dimensions (1-2 µm thick), they can provide in situ monitoring without any detriment to the mechanical properties, i.e. without generating defects, and preserving the matrix homogeneity. The characteristics of the sensor can be tailored through the fraction of CNT used in the resin. The steps of fabrication of spray layer-by-layer3 (sLbL) sensor will be explained as well as the electrical response of the sensor due to a mechanical deformation solicitation.
References: 1 E. T. Thostenson, T. W. Chou, Nanotechnology, 2008, 19, 215713 3 I. Pillin, M. Castro, S.N. Chowdhury, J. F. Feller, J. Compos. Mater. 2015. 3 C. Robert, J.F. Feller, M. Castro, ACS Appl. Mater. Interfaces, 2012, 4, 3508–3516
A:P09 Flexible Strain Sensors with Stretchable Electrodes
TAKAHIRO KONDO, M. SATO, H. OKUZAKI, University of Yamanashi, Kofu, Yamanashi, Japan
We have developed stretchable and highly conductive films by casting a water dispersion of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) containing polyglycerin (PG). It was found that the PEDOT/PSS/PG films showed the electrical conductivity and elongation at break as high as 411 S/cm and 26%, respectively. Furthermore, we fabricated flexible strain sensors consisting of ionic liquid/polyurethane elastomer (IL/PU) gel with the PEDOT/PSS/PG electrodes spray-deposited on both sides of the gel. Upon stretching by 50%, the resistance changed reversibly without disconnection in spite of the fact that the elongation at break of the PEDOT/PSS/PG electrodes was only 26%. This indicated that the conductive paths still remain in the electrode because cracks caused by stretching are thin and short, keeping the contact in the bulk state. Interestingly, the strain sensor was still conductive even after stretching by up to 180%, demonstrating that the PEDOT/PSS/PG could be used as stretchable electrodes of the flexible strain sensors.
A:P10 Nanocomposites of Aged Pseudoboehmite with Nylon 6,12
A.L. NASCIMENTO, A.H. MUNHOZ JR., C. DENUZZO, G.C. GOMES, L.F. MIRANDA, M.V. ROSSI, University Presbyterian Mackenzie, São Paulo, SP, Brazil
Polymer nanocomposites are composed of nanoscale particles embedded in a matrix. Addition of small amounts of an inorganic nanoparticles in a polymeric matrix can significantly improve the mechanical properties of composites as compared with the pure polymer. The high surface area of the nanoparticles of inorganic materials can promote the dispersion in the polymeric matrix, and the obtained properties are strongly related to the homogeneity of the dispersion. In that work, nylon nanocomposites of 6,12 with aged pseudoboehmite were obtained using octadecylamine to promote unity between the polymer and the pseudoboehmite. The pseudoboehmite was characterized by scanning electron microscopy (SEM), bending strength, Izod impact test, differential thermal analysis, thermogravimetric analysis, high deflection temperature, Vicat softening point. The addition of pseudoboehmite promoted increased in the melting temperature of the nanocomposite and increased the elasticity module showing the interaction with the polymer matrix pseudoboehmite probably by modifying its crystal structure.
A:P12 Influence of Concentration of the Nanofiller Pseudoboehmite in Thermal and Mechanical Properties in Polystyrene Compounds
L.F. DE MIRANDA, A.H. MUNHOZ JR., T.J. MASSON, M.V. ROSSI, Universidade Presbiteriana Mackenzie, Sao Paulo, Brazil
Polymeric nanocomposites are hybrid materials, where fillers with nanoscale dimensions are dispersed in a polymeric matrix. The fillers have a high surface area, promoting better dispersion in the polymeric matrix and therefore an improvement in physical properties of the composite depending on the homogeneity of the material. In the present work, nanocomposites of polystyrene with different concentrations of pseudoboehmite obtained by a sol-gel process, and treated with octadecylamine were prepared. The nanocomposites were characterized by thermal and mechanical tests. The addition of pseudoboehmite caused a reduction of the melting flow during the production of the composites evidencing the interaction of pseudoboehmite with the polymeric matrix. The addition of pseudoboehmite promoted an increase of the thermal and mechanical properties.
A:P13 Effect of Al2O3 Nano Filler on Conductivity and Optical Properties of PEI-Based Composite Polymer Electrolytes for Electrochromic Windows
O. SAKARYA1, S. KURAMA2, G. GUNKAYA3, 1Anadolu University, Faculty of Engineering, Dept. of Materials Science and Engineering, Eskisehir, Turkey; 2Anadolu University, Faculty of Aeronautics and Astronautics, Eskisehir, Turkey; 3Anadolu University, Faculty of Fine Arts, Dept. of Ceramic and Glass, Eskisehir, Turkey
Electrochromic Windows (ECWs) are commonly used in architecture both as the improving of indoor comfort of buildings and as in order to minimizing the carbon foot print of buildings throughout recent years. ECWs allow to control inflow visible light and solar irradiance into buildings and comprise of 7 layers. Electrolyte is located in the center of structure and play an essential role for working of ECWs. In this study, polymer electrolytes, which consist of Polyethyleneimine: Lithium bis (PEI:LiTFSI), were characterized by using dielectric/impedance spectroscopy, differential scanning calorimetry and FT-IR spectroscopy. In the first part of the study, temperature dependence ionic conductivities of PEI:LiTFSI electrolytes were determined by Arrhenius behavior. Additionally, glass transition temperatures and optical properties of that electrolytes were measured. In second part, the effect of Al2O3 nano powders addition on ionic conductivity, glass transition temperature and optical properties of PEI:LiTFSI electrolytes was investigated. Finally, the effect of adding of propylene carbonate (PC) and ethylene carbonate (EC) on interested properties of PEI:LiTFSI electrolytes was examined, and also the effect of Al2O3 adding on properties of PEI:LiTFSI:PC:EC electrolytes was tested.
A:P19 Site-specific Photo-rewritable Surfaces
LEI LI, X. DU, W.Q. FENG, P.A. LEVKIN, Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
The fabrication of patterned surfaces with spatially resolved chemical functionality has attracted considerable attention, as it enables precise deposition of nanoparticles, biomolecules, cells and other substrates on the nano- or microscale, which is crucial to many applications in microfluidics, microelectronics and biotechnology. In most cases, the patterned surface is permanently modified, which limits possible the reversible modifications or dynamic applications of such surfaces. Thus, it is highly desirable to develop the surface with the permanent pattern and the reversible functionality. Herein, we propose a site-specific photo-rewritable surface. It’s only on the specific area of the patterned surface that a reversible photo reaction takes place. This design provides two apparent advantages: (1) surface chemistry can be reversibly tuned without the loss of the pattern and the background chemistry and topology, (2) more complex patterns could be reversibly introduced on the same background via a reversible photo reaction. We foresee that this site-specific photo-rewritable surface will be useful for the fabrication of renewable patterns and the development of dynamic patterns with the ability of reversible deposition and release of various substrates.
A:P20 All-organic Supercapacitors Using PEDOT/PSS Flexible Electrodes
HARUKI SAITO, H. TAKEZAWA, H. OKUZAKI, University of Yamanashi, Kofu, Yamanashi, Japan
Supercapacitors, capable of storing electric charges at the electric double-layer between electrode and electrolyte, have great advantages of fast charging/discharging and long life cycle. In this study, flexible and lightweight all-organic supercapacitors have been fabricated using a conductive polymer, poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS), as collector electrodes instead of the etched aluminum foil. The collector electrodes were fabricated by casting the PEDOT/PSS water dispersion on Polyimide substrates. The electrical conductivity and sheet resistance of the PEDOT/PSS collector electrode were 800 S/cm and 0.8 Ω/sq, respectively. Subsequently, N-methyl-2-pyrrolidone (NMP) solution of active carbon (AC), Ketjenblack (KB), and poly(vinylidene fluoride) (PVDF) was bar-coated on the collector electrodes as an active layer. Finally, the all-organic supercapacitor was fabricated by sandwiching a separator containing propylene carbonate solution of 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) as an electrolyte with two electrodes. It was found that the capacitance and internal resistance of the flexible all-organic supercapacitor with a composition of AC:KB:PVDF = 8:1:1 were 46.2 F/g and 12.5 Ω, respectively.
A:P23 Fabrication and Properties of Naproxen Transdermal Patches Using Deproteinized Natural Rubber for Electric Field Controlled Drug Delivery
R. KAEWCHINGDUANG, A. SIRIVAT, The Petroleum and Petrochemical College, Chulalongkorn University, Bangkok, Thailand
Transdermal drug delivery system (TDDS) is the alternative route to provide controlled continuous delivery of drugs through the skin to the systemic circulation. The major advantage of TDDS is the ability to avoid the first-pass metabolism. However, TDDS has certain limitations such as the level of drug permeation across the skin and the diffusion of drug through the drug matrix are too low. In addition, the drug size has an adverse effect on the permeation. To improve those limitations, the electrical potential and conductive polymer were applied. In this work, an attempt was made to design a transdermal patch consisting of naproxen as the model drug and deproteinized natural rubber as the drug matrix. The drug permeation was shown to improve by applying electrical potential and conductive polyazulene as the drug carrier. These transdermal patches were characterized in details for the thickness, content uniformity, morphology, and in-vitro permeation.
A:HP26 Emerging π-conjugated Stretched and Contracted Helices and their Stimuli Induced Mutual Conversions of Substituted Polyacetylenes Prepared using an Organo-rhodium Catalyst
MASAYOSHI TABATA, YASUTERU MAWATARI, Center of Environmental Science and Disaster Mitigation for Advanced Research, Muroran Institute of Technology, Muroran, Hokkaido, Japan; Faculty of Science and Technology, Department of Applied Chemistry and Bioscience, Chitose Institute of Science and Technology, Chitose, Hokkaido, Japan
Interconvertible stretched and contracted helices of mono-substituted polyacetylenes (SPA)s prepared using a [Rh(norbornadiene)Cl]2-amine or alcohol catalyst are demonstrated along with the reason for why the Rh catalytic system was used. The interconversions between their helices with color changes in the solid state were controlled by choosing the polymerization solvents, substituents and/or external stimuli. The accordion-like helix oscillation, HELIOS, of the aliphatic polyacetylene ester main chain was found in a solution where restricted rotations around the O-C bond in the ester side-chain are dynamically synchronized. The magnetic behavior of the cis and trans radicals of SPAs produced through the rotational scission of the cis C=C bonds is also reported.
A:HP27 Patterning Wrinkles by Shape Memory Polymer
JING ZHONG, School of Civil Engineering, Harbin Institute of Technology. Harbin, P.R. China
Wrinkles are ubiquitous in nature as a form of mechanical instability, occurring in a vast different systems range from animal skin to lava flow. They were previously treated as a nuisance to be avoided, but in recent years, wrinkles been taken advantage as exquisite patterns for advanced applications. Wrinkles can be formed in a piece of thin film coated on pre-stretched rubber or shape memory polymers (SMPs). Upon releasing of the substrate pre-strain or heating SMP to trigger its shrinking, the compressive stress generated by the substrate can buckle the coated thin film and eventually result to features of wrinkles. As a geometric pattern, the most important characteristic geometrical features (CGFs) of wrinkles are wavelength, amplitude and orientation. However, none of the CGFs can be adjusted locally and arbitrarily for a given thin film-substrate system. All of those wrinkles are either oriented in the same direction (for one way contraction) or in a random fashion (for two way contraction), and the realization of gradual alteration of the wrinkle orientation in a single piece of thin film has never been achieved. In this study, we focus on the patterning and orientation control of the wrinkles by heating SMP substrate locally. Instead of the formation of wrinkles all over the thin film, we patterned wrinkles locally and at the same time, altered their orientation gradually, in a single piece of thin film.