A fast (30 s) thermoresponse and rapid (30 min) self-healing were achieved by noncovalently incorporating a small fraction of poly(N-isopropylacrylamide) (PNI-PAM) nanogels (≤0.18 wt %) into a benzyl methacrylate-cooctadecyl methacrylate-co-methacrylic acid (BOMA-16) polymer matrix. The PNIPAM serves as the thermoresponsive component while the BOMA-16 provides self-healing via hydrophobic associations. The PNIPAM/BOMA-16 composite showed tunable lower critical solution temperature and up to 95% more visible light modulation (ΔT) than the same concentration of PNIPAM by itself. Conversely, the PNIPAM nanogels (≤0.18 wt %) served as reinforcements and increased the storage modulus of the PNIPAM/BOMA-16 hydrogel by up to 2.7 times relative to a BOMA-16 hydrogel. Using different analytical techniques, we show that the synergistic thermoresponsive light modulation is due to a hydrophilic−hydrophobic phase transition and clustering of the PNIPAM nanogels facilitated by the BOMA-16. The synergistic optical effect is also observed for mixtures of PNIPAM and other polyelectrolytes.

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Block polymers are an important class of materials offering unique and useful properties different from random polymers. Because of their tailored structure, these materials present synthetic challenges. For this reason, it is necessary to provide a thorough structural analysis to drive the synthetic effort. We describe an analytical methodology that includes size exclusion chromatography (SEC), quantitative 13 C NMR, and 1 H pulsed gradient spin echo (PGSE) NMR coupled with direct exponential curve resolution algorithm (DECRA) data analysis. The combination of these complementary techniques provides a comprehensive assessment of the chemical structure of the final polymeric material, including the detection and quantification of homopolymer formation, compositional heterogeneity with molecular weight, and monomer sequencing. We present work on two different linear block polymers: poly(styrene-b-allyl methacrylate) and poly[styrene-b-(styrene-alt-maleic anhydride)].