@article{vargantwar_mittal_hauser_smith_hashem_2014, title={Novel treatment route for preparation and characterization of carboxymethyl cellulose}, volume={1}, DOI={10.14504/ajr.1.1.1}, abstractNote={A novel route of partial carboxymethylation, termed pad-dry-pad-cure, was investigated using conventional fabric processing equipment. The effect of process parameters such as concentration of sodium hydroxide, curing time, and concentration of ammonium monochloroacetate on the carboxymethylation content was probed. The treatment was characterized for uniformity by laser scanning confocal microscopy and for changes in fiber cross-sectional geometry by scanning electron microscopy (SEM). Confocal micrographs revealed the occurrence of treatment uniformly across the fiber cross sections, whereas SEM showed the resultant oval cross sections of the treated fibers.}, number={1}, journal={AATCC Journal of Research}, author={Vargantwar, P. H. and Mittal, K. and Hauser, P. and Smith, B. and Hashem, M.}, year={2014}, pages={1–5} } @article{vargantwar_brannock_tauer_spontak_2013, title={Midblock-sulfonated triblock ionomers derived from a long-chain poly[styrene-b-butadiene-b-styrene] triblock copolymer}, volume={1}, ISSN={["2050-7496"]}, DOI={10.1039/c2ta00022a}, abstractNote={Selective sulfonation of a poly[styrene-b-butadiene-b-styrene] (SBS) triblock copolymer has been performed with a sulfur trioxide–dioxane (SO3–dioxane) complex to generate midblock-sulfonated triblock ionomers possessing varying degrees of sulfonation (DOS). Products of the sulfonation reaction have been characterized by proton nuclear magnetic resonance and Fourier-transform infrared spectroscopies to ensure sulfonation only involves the B midblocks. Due to this targeted sulfonation, the lower glass transition temperature (Tg) disappears completely in all the ionomers examined, indicating that the formation of ionic aggregates restricts the mobility of the B midblocks. Such aggregates hinder microphase separation and promote a diffuse interface, as established by progressive broadening of the upper Tg with increasing DOS. Additional evidence of diffuse interfaces and matrix densification is provided by small-angle X-ray scattering, which reveals a concurrent size reduction in microdomain spacing with increasing DOS. A sulfonation-induced order–order morphological transition from cylinders to lamellae is likewise observed. Due to the retention of microphase-separated glassy microdomains that serve as physical crosslinks, these triblock ionomers are capable of absorbing remarkably high solvent levels and forming highly swollen gel networks in polar media, thereby making them suitable for use in hygiene and healthcare applications, as well as in devices requiring ion transport.}, number={10}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Vargantwar, Pruthesh H. and Brannock, Molly C. and Tauer, Klaus and Spontak, Richard J.}, year={2013}, pages={3430–3439} } @article{vargantwar_brelander_krishnan_ghosh_spontak_2011, title={(Electro)mechanical behavior of selectively solvated diblock/triblock copolymer blends}, volume={99}, ISSN={["1077-3118"]}, DOI={10.1063/1.3666783}, abstractNote={Thermoplastic elastomeric triblock copolymers swollen with a midblock-selective solvent form a highly elastic physical network that can exhibit remarkable electromechanical properties (high actuation strains and electromechanical efficiency with low hysteresis upon cycling) as dielectric elastomers. One unexplored means of controllably altering the midblock network and the corresponding (electro)mechanical properties at constant copolymer concentration is to substitute non-network-forming diblock for triblock copolymer molecules. In this study, we demonstrate that the incorporation of composition-matched diblock molecules into selectively solvated triblock systems results in softer materials that are less physically crosslinked and thus capable of undergoing electroactuation at reduced electric fields.}, number={24}, journal={APPLIED PHYSICS LETTERS}, author={Vargantwar, Pruthesh H. and Brelander, Sarah M. and Krishnan, Arjun S. and Ghosh, Tushar K. and Spontak, Richard J.}, year={2011}, month={Dec} } @article{krishnan_vargantwar_ghosh_spontak_2011, title={Electroactuation of Solvated Triblock Copolymer Dielectric Elastomers: Decoupling the Roles of Mechanical Prestrain and Specimen Thickness}, volume={49}, ISSN={["1099-0488"]}, DOI={10.1002/polb.22331}, abstractNote={AbstractDielectric elastomers (DEs) constitute a class of electroactive polymers that are becoming increasingly important as lightweight and mechanically robust replacements for conventional transducers and actuators. Because of their inherent cycling resilience, they also show tremendous promise as energy‐harvesting media, as well as smart sensors and microfluidic devices. Recent studies have demonstrated that DEs composed of midblock‐solvated triblock copolymers exhibit attractive electromechanical attributes such as giant electroactuation strains at relatively low electric fields at high conversion efficiency. Moreover, the properties of these readily processable systems are highly composition‐tunable, thereby making them ideal candidates for a detailed study of the coupling between initial specimen thickness and mechanical prestrain, which is frequently used to reduce specimen thickness before actuation to lower the voltage required to achieve electroactuation. Conventional wisdom based on the notion of an ideal DE indicates that electroactuation should only depend on pre‐actuation specimen thickness, but we report results that unequivocally indicate a more detailed material/process description is required. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1569–1582, 2011}, number={22}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Krishnan, Arjun S. and Vargantwar, Pruthesh H. and Ghosh, Tushar K. and Spontak, Richard J.}, year={2011}, month={Nov}, pages={1569–1582} } @article{vargantwar_roskov_ghosh_spontak_2012, title={Enhanced Biomimetic Performance of Ionic Polymer-Metal Composite Actuators Prepared with Nanostructured Block Ionomers}, volume={33}, ISSN={["1022-1336"]}, DOI={10.1002/marc.201100535}, abstractNote={AbstractIonic polymer–metal composites (IPMCs) represent an important class of stimuli‐responsive polymers that are capable of bending upon application of an electric potential. Conventional IPMCs, prepared with Nafion and related polyelectrolytes, often suffer from processing challenges, relatively low actuation levels and back relaxation during actuation. In this study, we examine and compare the effects of fabrication and solvent on the actuation behavior of a block ionomer with a sulfonated midblock and glassy endblocks that are capable of self‐organizing and thus stabilizing a molecular network in the presence of a polar solvent. Unlike Nafion, this material can be readily dissolved and cast from solution to yield films that vary in thickness and exhibit enormous solvent uptake. Cycling the initial chemical deposition of Pt on the surfaces of swollen films (the compositing process) increases the extent to which the electrodes penetrate the films, thereby improving contact along the polymer/electrode interface. The maximum bending actuation measured from IPMCs prepared with different solvents is at least comparable, but is often superior, to that reported for conventional IPMCs, without evidence of back relaxation. An unexpected characteristic observed here is that the actuation direction can be solvent regulated. Our results confirm that this block ionomer constitutes an attractive alternative for use in IPMCs and their associated applications.}, number={1}, journal={MACROMOLECULAR RAPID COMMUNICATIONS}, author={Vargantwar, Pruthesh H. and Roskov, Kristen E. and Ghosh, Tushar K. and Spontak, Richard J.}, year={2012}, month={Jan}, pages={61–68} } @article{vargantwar_shankar_krishnan_ghosh_spontak_2011, title={Exceptional versatility of solvated block copolymer/ionomer networks as electroactive polymers}, volume={7}, ISSN={["1744-6848"]}, DOI={10.1039/c0sm01210f}, abstractNote={Responsive materials possess properties that change abruptly when exposed to an external stimulus, and electroactive polymers constitute examples of robust, lightweight materials that change shape upon electrical actuation. We demonstrate that solvated block copolymer networks afford tremendous versatility in designing electronic and ionic electroactive polymers. As dielectric elastomers, styrenic block copolymer systems attain extraordinary actuation strains approaching 300%, along with high electromechanical coupling efficiencies. Changing the solvent improves the blocking stress and yields remarkably high energy densities, while providing a unique opportunity for mechanical impedance matching and control of shape recovery kinetics, as well as mode of deformation. Dielectric elastomers composed of acrylic copolymers actuate beyond 100% in-plane strain without any prestrain, whereas block ionomer networks swollen with ionic solutions yield ionic polymer–metal composites, which actuate by bending. Selective solvation of block copolymer networks represents an effective and largely unexplored means by which to tune the function and properties of electroactive polymers through systematic manipulation of copolymer and solvent attributes.}, number={5}, journal={SOFT MATTER}, author={Vargantwar, Pruthesh H. and Shankar, Ravi and Krishnan, Arjun S. and Ghosh, Tushar K. and Spontak, Richard J.}, year={2011}, pages={1651–1655} } @article{vargantwar_smith_hauser_2007, title={Preparation of zwitterionic cotton fabrics and their wrinkle-resistant performance}, volume={7}, number={12}, journal={AATCC Review}, author={Vargantwar, P. H. and Smith, B. and Hauser, P.}, year={2007}, pages={42–46} }