David Attenborough in Blue Planet II did what many polymer scientists in my field have been trying to do for years: Convince the public and government that the challenges of plastic waste are real and need to be fixed. This talk will tell two brief stories of how monomer design shapes solutions for challenges in materials sustainability. One story deals with monomers for potential packaging applications, where the source, process and end-of-life are all rooted in sustainable principals. The second story introduces monomers that are some of the least “sustainable” we’ve worked with, but they may play a much more important role in improving the health of our planet and its ecosystem.
Story 1: Ring opening polymerisation of structurally diverse 1,3-dioxolan-4-ones (DOX monomers) affords isotactic and atactic polymers depending upon catalyst and reaction conditions, where avoiding epimerization is essential when deriving stereoregularity from enantiopure α-hydroxy acids. For example, isotactic poly(mandelic acid)s access biodegradable polystyrene mimics with high Tgs. Scale up and optimisation of these materials, as well as broadening monomer scopes, yields a family of commodity plastics with desirable thermal properties whilst retaining hydrolytic and enzymatic degradability.
Story 2: Steric bulk prevents the formation of strong bonds between Lewis acids and bases in frustrated Lewis pairs (FLPs), masking their reactivity. We recently developed the first fully macromolecular FLPs, built from linear copolymers that containing either a sterically encumbered Lewis base or Lewis acid as a pendant functional group. Mixtures of the B- and P-functionalized polystyrenes do not react, with the steric bulk of the functional monomers preventing the favourable Lewis acid base interaction. The resulting gel is dynamic, can self-heal, is heat responsive, and can be reshaped post-gelation. Second generation systems are designed to capture carbon dioxide, allowing for a functional material to potentially derive value from a waste gas.