SUSCHEM - RING OPENING POLYMERIZATION IN AQUEOUS DISPERSION

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Polymers are long-chain molecules that consist of a repeating chemical structural unit. With over 300 million ton produced annually in the form of plastics, polymers are truly ubiquitous to our society. Unfortunately, most of these polymers are not biodegradable, and even if a fraction is recycled, eventually most polymers end up in a landfill, which is an unsustainable and environmentally taxing proposition. Polymers are synthesized using a chemical reaction called "polymerization." Emulsion polymerization is a very common industrial technique used for the production of a wide variety of polymers, including rubber, latex, and coatings. Thus far, it has not been possible to use this process to manufacture biodegradable polymers. This research project aims to develop a novel strategy to synthesize biodegradable polymers by emulsion polymerization. This research project employs tools and concepts from polymer science, catalysis, and reaction engineering and enables the training of both graduate and undergraduate students. An outreach program at the St. Elmo Brady STEM Academy seeks to inspire students from underrepresented groups attending rural schools in central Illinois about science. Hands-on experimental modules demonstrating polymer synthesis and the importance of polymer recycling for a sustainable environment are being developed.The objective of this research project is to develop a new methodology for performing ring-opening polymerization of cyclic esters in aqueous dispersions to generate biodegradable polymer latexes. One aim is to pursue catalytic emulsion polymerization with water-sensitive catalysts by relying on the encapsulation of the catalyst within a hydrophobic capsule dispersed in water, where the shell of this capsule is permeable to the monomer but not to water. Following a top down approach, micrometer-sized block copolymer capsules prepared using a microfluidic technique will be used initially to establish a proof-of-concept. These large capsules permit the determination of the rate of polymerization and rate of transport, information that can be used to develop a model to predict the potential of more scalable, seeded emulsion ring-opening polymerization with nanometer-sized capsules. The microstructure of the block copolymers used to form the semipermeable shell of the capsules are being tuned to increase monomer transport while decreasing the rate of transport of water. Optimization of the rates should allow for the capsules to be decreased in size to tens of nanometers, leading to the first seeded catalytic ring-opening polymerization in aqueous dispersion.