Thiol-ene photopolymerizations have been employed to facilitate the formation of a variety of degradable networks utilizing hydrolyzable moieties such as esters, and anhydrides; however, acetals have received minimal attention in this context. Acetals are an attractive option for the design of pH-sensitive crosslinkers in degradable materials due to their straightforward synthesis and to the formation of charge-neutral and potentially non-toxic degradation products. Acetals generally exhibit outstanding stability under basic conditions while readily undergoing hydrolysis back to the parent aldehyde or ketone and alcohol when exposed to acidic conditions in the presence of water. This presentation will focus on our efforts to use thiol-ene step-growth polymerizations for the formation of homogeneous, degradable networks with well-defined molecular weight between each crosslink junction. The mechanism of step-growth polymerization ensures that any degradable linkage in one monomer will be present within every crosslink junction of the network (Figure 1). Exposing the step growth network to the required stimulus (acidic pH in this work) triggers the cleavage of every accessible crosslink junction ultimately resulting in complete network degradation into small molecule constituents. We show that degradation profiles are readily tunable via monomer design.

Exploiting step-growth thiol-ene photopolymerizations for design of degradable poly(thioether acetal) networks

2019 Spring National Meeting

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