End-capped poly(4,5-dichlorophthalaldehyde): A stable self-immolative poly(aldehyde) for translating specific inputs into amplified outputs, both in solution and the solid state

We recently reported that poly(4,5-dichlorophthalaldehyde) (PCl₂PA) is an effective self-immolative CD_r polymer for prototyping multi-stimuli-responsive three-dimensional polymeric materials with response properties that are inspired by the behaviour of certain biological materials in plants. In this article we detail the design and synthesis of PCl₂PA, describe its ability to respond to specific stimuli, and compare and contrast PCl₂PA with poly(phthalaldehyde) (PPA), which is the self-immolative CD_r predecessor of this new poly(acetal). This article illustrates the favourable attributes of PCl₂PA, including its dose-dependent solution-phase response to Pd(0). Taken together, these studies reveal the unique and useful attributes of PCl₂PA for providing selective amplified responses to specific stimuli, both in solution and the solid state.