Smart Polymers for Bioreplication and Self-Healing

Date of Award

December 2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biomedical and Chemical Engineering

Advisor(s)

Patrick T. Mather

Keywords

Bioreplication, Contact Angle, Hydrophobicity, Self-Healing, Shape Memory, Smart Polymer

Subject Categories

Engineering

Abstract

My research consisted of utilizing the shape memory effect (SME) found in shape memory polymers (SMPs) for two unique applications. First, a natural surface pattern that possessed hydrophobic properties was replicated onto the surface of an SMP by using a soft lithography technique. By following the SME, SMP replicas were fixed into a flat, temporary shape that yielded hydrophilicity. Shape recovery restored the surface features of the hydrophobic, permanent shape. The next project consisted of fabricating a self-healing thermoplastic composed of a SMP and a healing agent. After inflicting damage, the SMP was found capable of autonomous crack closure via the SME which was thermally triggered and the healing agent would seal the damaged areas.

This thesis is arranged in the following manner: Chapter 1 gives an introduction to shape memory polymers and outlines of the bioreplication and self-healing projects. Chapter 2 discusses the transfer of a hydrophobic surface pattern found in nature onto an epoxy SMP by using polydimethylsiloxane (PDMS) as the elastomer molding material. The epoxy SMP was cast and cured over the PDMS molds which transferred the surface features and thus serving as the permanent shape. Deforming and fixing the permanent shape to a flat shape resulted in hydrophilicity. By recovering the surface features when heated above the glass transition, the features were recovered which restored hydrophobicity. Chapter 3 introduces a self-healing thermoplastic composed of a SMP and healing agent in an interpenetrating network. This combination of an SMP and healing agent possesses self-healing exhibits the shape memory assisted self-healing (SMASH) effect. poly(tBA-BA) was synthesized to serve as the SMP component and poly(ɛ-caprolactone) was used as the healing agent. Composites containing different amounts of the SMP and healing agent were fabricated by dual electropsinning in which both polymers were electrospun simultaneously into fiber mats. The fiber mats were molded into films by compression molding for self-healing assessment. Chapter 4 summarizes the results from both projects and suggests future research following this work.

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