Self-Immolative Polymers

Self-immolative linear polymers are a recently developed class of materials that typically undergo head-to-tail depolymerization in response to the cleavage of stimuli-responsive end-caps from their termini. These polymers have been inspired by self-immolative dendrimers and oligomers that undergo cascades of cyclization and/or elimination reactions in response to the activation or cleavage of a trigger moiety. During the past decade, several backbones have been introduced including polycarbamates, polycarbonates, polythiocarbamates, polythiocarbonates, polyacetals, and poly(benzyl ether)s. These backbones have been tuned to control the depolymerization rate, and end-caps responsive to stimuli including enzymes, light, heat, acid, and small molecules such as fluoride ions have been incorporated. They have been explored for the development of sensing devices, microcapsules, and nanoscale assemblies such as micelles and vesicles. In these applications, their depolymerization in response to end-cap cleavage affords effective amplification of these stimuli, resulting in enhanced sensitivity. Their depolymerization kinetics has also been studied in detail. This article will review the development and current status of both the chemistry and application of linear self-immolative polymers.