Self-Immolative Polymers Containing Rapidly Cyclizing Spacers: Toward Rapid Depolymerization Rates

Self-immolative polymers containing 4-hydroxybenzyl alcohol alternating with either N-methylaminoethanol or 2-mercaptoethanol spacers were synthesized and demonstrated to controllably depolymerize in response to the cleavage of a stabilizing end-cap from the polymer termini. These new polymers depolymerized at much higher rates than the previously reported polymer containing an N,Ni-dimethylethylenediamine spacer, with the time scales for complete depolymerization reduced from days to hours. Herein, we report the design and synthetic strategies for incorporating both stronger nucleophilic and electrophilic sites to induce faster cyclization reactions, which are known to be the rate-limiting steps in the depolymerization of this class of self-immolative polymers. These modifications and results demonstrate that the proposed structure-to-property relationships translate to the development of new polymer backbones for applications that require rapid depolymerization rates.