University of North Carolina at Chapel Hill Graduate School
Doi
Abstract
This dissertation aims to advance the current understanding of graft polymer architectures and the new and unique properties that can be accessed by their application to elastomeric materials. Current accessible polymer materials are synthesized from linear polymer architectures, which have been implemented to great effect and restructured the economy and technology of the world. However, in the case of linear elastomers the only architectural control parameter that can be tuned is the crosslink density,??,which imposes a fundamental limitation on the accessible material properties limiting their modulus(?>100???),maximum extensibility(????<5), and strain-stiffening characteristics(?<0.20).Here we have studied graft polymer elastomers made from poly(butyl acrylate) (PBA) to draw correlations between their architectural parameters (sidechain length-???,grafting density-??, backbone length-???, and crosslink density-??) and their material properties. A series of loosely grafted comb polymers in the melt were examined by oscillatory shear rheology to study how the entanglement modulus of such architectures can be tuned by varying the ???, and ??. A model system created from PBA graft polymer elastomers was introduced and used to correlate the mechanical and swelling properties of graft polymer elastomers with their associated architectural parameters. Of particular note it was found that graft polymer architectures could provide a unique opportunity to develop tissue like gels, whose mechanical properties can be tuned independently of their solvent fraction. Lastly, the electroactive properties of bottlebrush elastomers were shown to be large strains at low operating voltages.Doctor of Philosoph
