Branched Polymers for Enhancing Polymer Gel Strength and Toughness

The objective of this project is to develop robust and scalable synthetic methods to access polymer network and solvent macromolecules with complex chain architectures and highly branched molecular structures. The introduction of branching points in the polymer network and solvent will significantly enhance the strength and toughness of polymers gels through increased physical chain entanglements. In particular, we have focused on synthesizing and characterizing poly(dimethylsiloxane) (PDMS) based materials with well-defined chain lengths and branching points for use in polymer gels. This research has yielded four major accomplishments related to the proposal objectives including: (1) conducting successful synthesis of a star shaped PDMS solvent; (2) demonstrating greater than two times improvements in both strength and toughness of the polymer gel due to incorporation of the star shaped solvent; (3) identifying synthetic strategies for increasingly complicated chain structures, such as H, pom-pom, comb, and dumbbell shaped molecules; and (4) employing anionic polymerization to prepare additional star shaped PDMS solvents of varying molecular weight and arm number. The original document contains color images.