Date on Master's Thesis/Doctoral Dissertation

5-2012

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Chemical Engineering

Committee Chair

Willing, Gerold A.

Author's Keywords

Hydrogel; Polypyrrole; Artificial muscle; Interpenetrating polymer network; Electroactive polymer; Hydrophilic pyrrole

Subject

Conducting polymers; Polymers in medicine; Myocardium

Abstract

Hydrophilic and conductive characteristics in polymers are mutually exclusive of each other. Hydrophilic polymer properties allow absorption of water up to several magnitudes above their dry weight. However, due to their molecular structure, they are not inherently conductive without the aid of a conductive element. Conductive polymers have molecular structures which permit current transfer via a series of delocalized electrons along the polymer backbone. Conversely, due to their organic nature, they are very hydrophobic and will not readily interact with hydrophilic elements. The motivation of this dissertation was to develop a biocompatible material that could potentially support the muscle like movement and performance of cardiac muscles for the treatment of congestive heart failure. To initiate this investigation, hydrophilic polymers and conductive polymers were separately examined and synthesized. Experimentation led to the selection of methacryamide and pyrrole monomers as the hydrophilic and conductive elements, respectively. Initial efforts to integrate these polymers proved challenging due to the hydrophobic nature of pyrrole and the hydrophilic nature of methacrylamide. To enhance the compatibility of pyrrole within the methacrylamide matrix, pyrrole was modified with a hydrophilic group. However, its location on pyrrole had to be selective in order to minimize disruption of the delocalized electrons along the polypyrrole backbone and losses in conductivity. Synthesis of the polymer compound with the methacryamide hydrogel matrix and modified pyrrole exhibited integration of the pyrrole into the hydrogel by diffusion of the pyrrole monomers into the hydrogel matrix and subsequent polymerization. Copolymers are characterized the combination of monomers in a random or specific arrangement along the backbone of the polymer complex, and composites are regarded as a dispersion of one material in a matrix of the second. This was an integration of two polymers interpenetrating each other into a woven polymer network. A unique compound was synthesized by integrating two physically incompatible polymer materials. Modification of the pyrrole to a hydrophilic molecule provided the ability to electropolymerize polypyrrole within the hydrogel matrix. An interpenetrating polymer network (IPN) with the integration of both hydrogel and conductive polymer elements were made feasible by this unique piecewise synthesis and design scheme.

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