Styrenic star polymers via RAFT polymerization

Structured polymers can be used in a host of applications from adhesives to catalysis. This project focuses on the synthesis of polystyrene-based star polymers by reversible addition-fragmentation chain transfer (RAFT) polymerization to achieve reproducible size and arm density for each star. RAFT polymerization is ideal for our future research goals because of the functional group tolerance of the method. Our optimization studies of arm-first synthesis of star polymers included altering the solvent, temperature, chain transfer agent (CTA), and ratios of reagents in the cross-linking reactions to make the cores of the stars. RAFT polymerization to make the polystyrene arm, also called the macro-CTA, proceeded with low dispersity and high end group fidelity. In the cross-linking reactions to form the cores of the star polymers, varying the ratio of macro-CTA to cross-linker to monomer significantly impacted the number of arms incorporated into each star and the overall efficiency of the reaction. Both crude and purified star polymer products were characterized via spectroscopic and chromatographic methodologies. Ongoing studies include the incorporation of functional monomers into the star polymer cores using the optimized synthesis.