Due to their modular, tunable nature and rapid cure kinetics, polymers made from radical-mediated thiol-ene photopolymerizations provide an interesting approach to the production of novel, degradable materials for single-use applications. In this work, a library of para-substituted bis-allyl benzylidene acetals was synthesized to evaluate the role of monomer electron donating or withdrawing substituent effects on the hydrolytic degradation behavior of resultant poly(thioether acetal) networks. Substituents examined ranged in inductive strength from cyano to 3,4,5-trimethoxy. Monomer half-lives were determined at various pH values via <sup>1</sup>H NMR spectroscopy. Each resin was prepared using a stoichiometric amount of bis-allyl monomer and commercially available pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) and polymerized via exposure to UV light. Monomer conversion was determined by real-time Fourier infrared transform (FT-IR) spectroscopy. These systems were then characterized to determine hydrophobicity, modulus, and glass transition temperature. The hydrolytic degradation behavior of the poly(thioether acetal) networks was assessed at a range of pH values to determine trends in network hydrolysis relative to established trends in monomer hydrolysis. Deviations in degradation kinetics and physical properties were used to explore the influence of monomer structure on resultant poly(thioether acetal) network properties and degradation behavior to guide the development of future classes of environmentally relevant degradable polymer networks.

Establishing substituent effects on hydrolytic degradation behavior of poly(thioether acetal) networks from thiol-ene photopolymerization

2019 Spring National Meeting

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