Optimizing the Synthesis of High Molecular Weight Thermoresponsive Triblock Copolymers for Processing Scalability

Stimuli-responsive block copolymers are used in a variety of applications including printable electronics, thermoresponsive spray coatings, and drug delivery systems. These polymers are especially favorable in applications due to their tunable properties, versatility, and potential scalability. Polymer architecture has a crucial role in responsiveness, and reversible addition-fragmentation chain transfer (RAFT) polymerization can be used to achieve well-controlled polymers. In this project, RAFT is used to synthesize low dispersity poly(N-isopropylacrylamide-b-dimethylacrylamide) (P(NIPAM-b-DMA)) triblock copolymers. Polymerization was carried out using two RAFT chain transfer agents, 2-(1-carboxy-1-methylethylsulfanylthiocarbonylsulfanyl)-2-methylpropionic acid (CMP) and 2-(dodecylthiocarbonothioylthio)-2-methylpropanoic acid (bis-DDMAT). CMP contains end carboxyl groups, while bis-DDMAT contains end dodecyl carbon chains creating different resulting triblock structures, which should lead to different behaviors in solution. While previous experiments utilizing these triblocks were limited to lower molecular weight polymers, larger molecular weight polymers tend to have higher tensile strength and better longevity in applications. Therefore, we are interested in raising the molecular weight of these polymers to study how this affects structure and processability. Following successful synthesis, cloud-point testing was performed to study optical properties of the polymers as a function of temperature. This work connecting polymer architecture to solution processability will be beneficial to increase the scalability of these stimuli-responsive polymers.