Hearon, Michael Keith (2014-11). Shape Memory Polymer Systems with Advanced Processing Capabilities and Tunable Mechanical Properties. Doctoral Dissertation.
Thesis
The ability of shape memory polymers (SMPs) to undergo geometric transformations upon exposure to stimuli has inspired application-driven research in a diverse array of scientific fields. The shape memory effect has been demonstrated in a number of polymeric systems, and recently the scientific community has shown a growing interest in developing shape memory polymer systems that exhibit other advanced material properties in combination with shape memory. High performance shape memory polymer (SMP) systems with tunable thermomechanical properties and good biocompatibility that can be processed using conventional thermoplastic processing techniques are of importance for a variety of industrial applications. For SMP-based medical devices in particular, the functional utility that arises from a clinician's ability to trigger geometric transformations after device implantation in the body is both multi-dimensional in nature and complex in conceptualization. The materials science of human physiology constitutes tremendous variations in tissue modulus and architecture, and consequently implantable devices may require SMPs that both exhibit highly tunable material properties and possess the ability to be processed into desired geometries using conventional thermoplastic processing techniques such as 3D printing, injection molding, extrusion or dip-coating. The tunability of material properties, toughness and processability of many SMP systems has been shown to be highly dependent on the nature and extent of crosslinking in the SMPs. This dissertation introduces a series of new amorphous, thermally actuated shape memory polymer systems that exhibit highly tunable material properties and advanced processing capabilities and to demonstrate these SMP systems viability as platform systems for medical device design. A special focus is also given to the development of new shape memory polymer systems derived from novel green formulations to stress the importance of building for a sustainable future from a materials engineering standpoint.
