Alternating copolymers of functional stilbene monomers with maleic anhydride or maleimides are new sterically crowded, chain stiffened, and precisely functionalized macromolecules. The recently established semi-flexible nature of these backbones, arising from the steric crowding of the 1,2-diphenyl groups from the stilbene monomers and the stiffening effect of five-member cyclic anhydride or imide units is the origin of interesting optical, surface area, and block copolymer solution complexation behavior exhibited by these materials. One thrust of the research in this project will focus on the solution properties, including rheology and self-assembly characteristics, of these semi-flexible polymers in organic solvents (non-ionic copolymers) and in aqueous media (ionic copolymers). The properties of interpolyelectrolyte complexes (IPECs) of small libraries of new all anionic and all cationic semi-flexible macromolecules under various external stimuli such as salt concentration and pH will be studied and the effect of charge density, placement, and chain stiffness on the IPECs elucidated using dynamic light scattering and other techniques. In addition, the effect of charge density and charge type on the aqueous solution behavior of self assembled complexes of new double hydrophilic block copolymers, containing a semi-flexible alternating copolymer block, will be investigated. A second thrust will involve studies of the effect of the semi-flexible contorted alternating copolymer structures on polymer properties such as surface area, gas permeability, and adsorbent properties in the solid state. New hybrid block copolymers based on poly(arylene ether sulfone) middle blocks will be synthesized with alternating copolymer end blocks and will be cast into films and the mechanical, morphological, and gas permeability properties studied. The nanoporous properties of hypercrosslinked polymer particles, containing semi-flexible alternating structures with selected types of functional groups, will be studied using a nitrogen adsorption method.
NON-TECHNICAL SUMMARY
Many technologies that are critical for the health, sustainability, and security of our society are dependent on the discovery and development of new polymeric materials that enable various types of devices in the optical and electronic areas to function or that can deliver payloads of therapeutics across biological membranes. The new polymeric materials resulting from the fundamental studies of this grant have potential for applications in a number of areas where enabling polymeric materials are indispensable components in successful innovations to products. Potential applications range from high surface area polymers for adsorbents for gases such as hydrogen and carbon dioxide, new water soluble polymers with tailored stimuli responsiveness for biomedical processes, and new hybrid polymer membranes for gas separations. Results from this research will be presented at major conferences and published in leading journals. Graduate students involved in this project will master the fundamentals of polymer science and engineering and will learn to work in a fast-paced interdisciplinary environment. These graduate students will have the opportunity to mentor undergraduate students in an NSF Research Experience for Undergraduates program at Virginia Tech and interact with industrial researchers in numerous outreach programs from the Virginia Tech polymer community. Participation in this research will provide students with a well-rounded education platform for preparation for successful careers in the science and technology based enterprise of our nation
