Epoxidation of Commodity Polydienes: An Operationally Simple and Acid-Free Platform for Generating Halohydrin-Containing Polymers with Tunable Properties

High Resolution Image Download MS PowerPoint Slide While postpolymerization modification (PPM) has been used extensively to imbue commodity polymers such as polyethylene, polyvinyl chloride, and polyurethane with unique thermal, chemical, and mechanical properties, the postpolymerization modification of polybutadiene (PBD) has received somewhat less attention. In this paper, we present a PPM method for synthesizing halohydrin-functionalized polymer products from isomerically mixed PBD that utilizes epoxides as an accessible, mineral-acid-free, chemoselective platform to yield halide-agnostic materials. We synthesized hydroxyhalogenated PBDs at varying levels of alkene functionalization, demonstrating trends in both M w and T g that correlate with the percent modification. We also scaled both steps of this reaction to a gram scale without a meaningful shift in polymer properties. We further applied this synthesis method to the functionalization of polyisoprene. Through our strategy, we obtained polymers that cannot be directly obtained from small molecules, demonstrated their tunable thermal properties, and completed this work with rigorous characterization at every stage of synthesis. Notably, these reactions were completed via a one-pot sequential addition with a single purification step using lithium salts as nucleophiles to avoid the use of any strong acids. This atypical choice for ring-opening allowed for improved molecular weight and dispersity properties after halohydrin formation.