Inspired from nature, polymeric materials that undergo phase transitions in response to external stimuli, such as temperature, ionic strength, and pH, represent an important category of materials synthesized by reversible addition fragmentation transfer (RAFT) polymerization, being widely investigated for drug delivery, separation, and diagnostics applications. Temperature-sensitive polymers display lower critical solution temperature (LCST) behavior in some solvents, which leads to a sudden decrease in solubility with the change in temperature, caused by conformational changes, and subsequent aggregation. Polymer stimuli responsiveness has complex relationships to architecture, copolymer distribution, 'blockiness', sequence length, etc. The focus of this study is to investigate the effects of the copolymer composition on LCST during synthesis via RAFT of N-isopropylacrylamide (NIPAM)/4-vinylbenzenesulfonic acid sodium salt (VB) copolymers. Due to the high difference in reactivity ratios, VB is rapidly consumed and leads to a composition drift toward NIPAM rich polymer, allowing, thus, tailoring the LCST behavior based on the specific chemical architecture of the resulting polymer.Synthesis and self-assembly properties of the copolymers are studied by light scattering based techniques. The ability to monitor the way both charge and hydrophilicity via copolymerization affects the LCST offers the possibility for reaction control, product development and optimization, while providing a powerful tool for understanding polymer physics and manipulating structure/function relationships.

Synthesis and characterization of thermally responsive copolymers by RAFT: The effect of composition on LCST and self-assembly behavior

247th National Meeting (2014)

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