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Novel Polyisobutylene-based Materials and Surfaces; Enzyme-catalyzed Functionalization and “Modular” Surface Construction.

Judit E. Puskas
Department of Polymer Science
The University of Akron
Akron, OH 44325-3909

Nanocopoeia Inc.
Volker Altsädt, Germany
Miroslawa El Fray, Poland

This project, the continuation of DMR-0509687, aims at the synthesis and characterization of novel self-assembling nanostructured thermoplastic elastomeric (TPE) biomaterials based on polyisobutylene (PIB). Specifically, efforts to synthesize new “Entropy-driven” TPEs (ENTPE) will continue. Under the previous NSF support it was discovered that the dendritic (arborescent or tree-like) arbPIB midblock of ENTPEs facilitates phase separation and TPE behavior even with very short plastic and elastomeric end blocks. These novel ENTPE materials were further reinforced with nano-size fillers (carbon and silica) to yield strong rubbery nanocomposites (ENTPEC), and their biocompatibility was demonstrated in vitro and in vivo in rabbits. Based on this discovery, new ENTPEs will be synthesized with short end blocks, capable of hydrogen bonding (e.g., polypeptides). Compounding these materials with nanofillers will yield new ENTPEC nanocomposites. In order to control surface chemistry and patterning for improved tissue integration, a new “modular” approach using ElectroNanoSpraying™ is proposed, which allows the construction of gradient surfaces with various chemistries and topologies. Spraying ENTPE onto the surface of ENTPEC will yield well-controlled nanopatterns of the same chemistry. Surface chemistry will be controlled by spraying low molecular weight (MW) functionalized PIBs (PIB-F) where F is a biologically active compound (nucleic acid base, peptide, protein, etc.) onto the surface of ENTPECs. The PIB-Fs will be precision synthesized from PIB-OH made by living carbocationic polymerization and functionalized using a novel enzyme-catalyzed transesterification process that yields complete conversion under mild conditions – this also emerged from the current grant. The “modular” approach will give unprecedented control over surface chemistry and surface patterning independently, and will contribute to new fundamental understanding of the effects of surface properties on the biocompatibility of polymeric materials.