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We report a modular approach in which a noncovalently cross-linked single chain nanoparticle (SCNP) selectively binds catalyst “cofactors” and substrates to increase both the catalytic activity of a Cu-catalyzed alkyne-azide cycloaddition reaction and the Ru-catalyzed cleavage of allylcarbamate groups compared to the free catalysts. 

A Ru-containing single chain nanoparticle (SCNP) was prepared in three steps using radical polymerization of pentafluorophenylacrylate, post-polymerization functionalization with three different alkylamines, and coordination of Ru. The polymer was characterized by 1 H NMR, 19 F NMR, UV-vis, and DLS. The catalytic activity of the Ru-SCNP for Ru-catalyzed cleavage of allylcarbamates was evaluated by fluorescence spectroscopy and a higher percent conversion and initial rate of reaction was observed when compared to that of the free catalyst in buffer and cell media. The catalytic SCNP was also shown to perform tandem catalysis with β-galactosidase. 

We report a photo-triggered, base generating, base propagating degradable polyurethane that is triggered by 365 nm UV light irradiation. A small area of this polyurethane material can be exposed to 365 nm UV light irradiation to generate basic species that can initiate a base propagated degradation process within the bulk material leading to global degradation without the need for continous UV irradiation. The polymer was synthesized by a polycondensation polymerization of a small amount of o -nitrobenzene diol 2 , a large amount of Fmoc-based diol 3 , and hexylmethylene diisocyanate. Integrating both photosensitive and base-sensitive carbamate moieties into the polymer 1 backbone provides the UV light-triggered base propagating degradable polyurethane material. Degradation studies of polymer 1 using 1 H NMR and gel permeation chromatography (GPC) suggest that initial UV irradiation triggers the degradation of the photosensitive o -nitrobenzene carbamate linkages, releasing a primary amino group that causes a cascade of amines to form by further degrading the remaining Fmoc carbamate groups. A bulk polyurethane film was prepared using Fmoc-based triol 4 as a monomer. UV-irradiation of a small localized area of the film initiates the propagation throughout, leading to efficient bulk degradation of the entire material. The amine degradation products could be utilized to make a one-pot epoxy adhesive, showing a potential upcycling application of this self-propagating degradable polyurethane system. 

A new type of base-triggered self-amplifying degradable polyurethane is reported that degrades under mild conditions, with the release of increasing amounts of amine product leading to self-amplified degradation. The polymer incorporates a base-sensitive Fmoc-derivative into every repeating unit to enable highly sensitive amine amplified degradation. A sigmoidal degradation curve for the linear polymer was observed consistent with a self-amplifying degradation mechanism. An analogous cross-linked polyurethane gel was prepared and also found to undergo amplified breakdown. In this case, a trace amount of localized base initiates the degradation, which in turn propagates through the material in an amplified manner. The results demonstrate the potential utility of these new generation polyurethanes in enhanced disposability and as stimuli responsive materials.