Targeted Design of Dynamic and Mechanical Bonds Towards Functional, Responsive Polymeric Networks

The implementation of dynamic chemistries into polymeric materials has led the way towards the development of functional materials that express a multitude of targeted responses. The use of dynamic covalent chemistries as well as mechanical bonds have shown great potential in the rapidly growing field of stimuli-responsive polymer materials. This dissertation will focus on moving towards tunable, functional polymer networks based on two different binding motifs: the dynamic thia-Michael addition and the doubly-threaded [3]-rotaxane. Although there is a great deal of dynamic covalent chemistries currently in use for functional materials, the thia-Michael addition reaction has only recently begun to be explored as a reversible bond in polymeric materials. Of particular interest is the benzalcyanoacetate Michael acceptor that undergoes dynamic exchange with thiols under ambient conditions. By mindfully adjusting the chemical composition of the Michael acceptor, it is possible to tune the chemical equilibrium of the thia-Michael reaction and hierarchically program thermomechanical and morphological properties of thia-Michael networks. The dynamic, phase separated films exhibit a range of functionalities including shape memory response and adhesive applications. Similarly, the development of an interlocked binding structure for crosslinked materials will lead to a host of unexplored responsive properties. Utilizing a metal-templated approach to target an interlocked [3]-rotaxane, progress towards the development of slide-ring gel materials will be described.