End-capped poly(4,5-dichlorophthalaldehyde) (PCl₂PA), which is a new self-immolative CD_r polymer with the unique capability of depolymerizing continuously and completely in the solid state when an end cap is cleaved from the polymer by reaction with a specific molecular signal, is described. End-capped poly(4,5-dichlorophthalaldehyde) is sufficiently stable to enable patterning of three-dimensional macroscopic polymeric materials by selective laser sintering. These unique materials are capable of 1) autonomously amplifying macroscopic changes in the material in response to specific molecular inputs, and 2) altering their responses depending on the identity of the applied signal. Thus, not only does end-capped PCl₂PA provide new and unique capabilities compared to the small subset of existing CD_r polymers, but it also provides access to a new class of stimuli-responsive materials.

Adhesives that selectively debond from a surface by stimuli-induced head-to-tail continuous depolymerization of poly(benzyl ether) macro-cross-linkers within a poly(norbornene) matrix are described. Continuous head-to-tail depolymerization provides faster rates of response than can be achieved using a small-molecule cross-linker, as well as responses to lower stimulus concentrations. Shear-stress values for glass held together by the adhesive reach 0.51±0.10 MPa, whereas signal-induced depolymerization via quinone methide intermediates reduces the shear stress values to 0.05±0.02 MPa. Changing the length of the macro-cross-linkers alters the time required for debonding, and thus enables the programmed sequential release of specific layers in a glass composite material.

End-capped poly(4,5-dichlorophthalaldehyde) (PCl₂PA), which is a new self-immolative CD_r polymer with the unique capability of depolymerizing continuously and completely in the solid state when an end cap is cleaved from the polymer by reaction with a specific molecular signal, is described. End-capped poly(4,5-dichlorophthalaldehyde) is sufficiently stable to enable patterning of three-dimensional macroscopic polymeric materials by selective laser sintering. These unique materials are capable of 1) autonomously amplifying macroscopic changes in the material in response to specific molecular inputs, and 2) altering their responses depending on the identity of the applied signal. Thus, not only does end-capped PCl₂PA provide new and unique capabilities compared to the small subset of existing CD_r polymers, but it also provides access to a new class of stimuli-responsive materials.

Adhesives that selectively debond from a surface by stimuli-induced head-to-tail continuous depolymerization of poly(benzyl ether) macro-cross-linkers within a poly(norbornene) matrix are described. Continuous head-to-tail depolymerization provides faster rates of response than can be achieved using a small-molecule cross-linker, as well as responses to lower stimulus concentrations. Shear-stress values for glass held together by the adhesive reach 0.51±0.10 MPa, whereas signal-induced depolymerization via quinone methide intermediates reduces the shear stress values to 0.05±0.02 MPa. Changing the length of the macro-cross-linkers alters the time required for debonding, and thus enables the programmed sequential release of specific layers in a glass composite material.

This review describes new types of smart materials that have the dual capabilities of responding to selective signals and providing an amplified response. Amplification arises from a signal-induced depolymerization reaction, where a single signaling event causes an entire polymer to convert to small molecules. When incorporated into a material, depolymerization of these polymers causes a change in shape, internal structure, or surfaces properties of the material. Moreover, the small molecules arising from depolymerization can play a role in the amplified response, particularly when they provide a secondary function (e.g., production of color or fluorescence). A brief overview of the current examples of linear depolymerizable polymers is provided, as are representative proof-of-concept applications of these polymers in the context of diagnostics and materials that remodel themselves and/or their surroundings. Together, these examples highlight the potential of this new class of polymers to provide unique and dramatic function to stimuli-responsive materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40992.

Herein we use small molecule models of stimuli-induced degradable/depolymerizable polymers to demonstrate that less aromatic releasing units provide faster rates of azaquinone methide-mediated release of benzylic phenols (a surrogate for a group released in a polymer) than highly aromatic releasing units. Copyright © 2013 John Wiley & Sons, Ltd.