Synthesis and characterization of poly(silyl urethane)s derived from glycol-modified silanes

Hydrolytically Stable and Thermo-Mechanically Tunable Poly(Urethane) Thermoset Networks that Selectively Degrade and Generate Reusable Molecules

Cross-linked polymeric networks that possess tunable properties and degrade on-demand have broad applications in today's society. Herein, we report on silyl-containing poly(urethane) (silyl-PU) thermoset networks, which are highly cross-linked stimuli-responsive materials with hydrolytic stability at 37.7 °C and 95% relative humidity, thermal stability of 280-311.2 °C, tensile properties of 0.38-51.7 MPa strength and 73.7-256.4% elongation, including storage modulus of 2268-3499 MPa (in the glassy state). However, unlike traditional (i.e., nondegradable) PU thermosets, these silyl-PUs selectively activate with fluoride ion under mild and static conditions to completely degrade, via cascading bond cleavages, and generate recoverable and reusable molecules. Silyl-PUs, as thin films, also demonstrated complete removal (within 30 min) from a strongly adhered epoxy thermoset network without altering the structure of the latter. Silyl-PU thermosets have potential applications in composite parts, vehicle and industrial coatings, and rigid plastics for personal devices, and may reduce environmental waste compared to nondegradable, single-use materials.

Novel Methods of Producing Low-Reflectance Coatings Utilizing Synergistic Effects of Polymer Phase Separation

Novel methods were developed to generate and characterize surface structures formed from polymer segregation within a powder coating system. A blend of unique acrylic polyol resins and low concentrations of matting agent afforded a durable coating exhibiting consistent low reflectance. An enhanced synergistic effect was observed from the phase separation and domain formation of the two polymeric resins with varying pendent hydroxyl group functionality and the incorporated matting agents. Together the domains and incorporated matting agents produced a significantly lower reflectance coating than the matting agent in combination with either polymeric resin alone. The rigorous thermal, optical, and spectroscopic analysis of the pigmented coating and control coatings culminated in the complete characterization of polymeric phases within the resulting coatings. Raman analysis of the control coatings via a distinct spectroscopic handle allowed for positive identification of the segregated polymer resins within the coating structure. Domains observed by optical microscopy within the control coating structure were chemically identified via Raman analysis as the high-hydroxyl content resin. Subsequent Raman mapping of the peak intensity over an entire cross-section provided consistent evidence for positive identification of the polymeric composition within the domain.