Synthesis, characterization, LCST-type behavior and unprecedented heating-cooling hysteresis of poly(N-isopropylacrylamide-co-3-(trimethoxysilyl)propyl methacrylate) copolymers

- Soluble poly(N-isopropylacrylamide-co-3-(trimethoxysilyl)propyl methacrylate).
- Condition and composition dependent LCST-type thermal phase transitions.
- Unprecedented composition dependent heating-cooling hysteresis.
- Above cloud point, in-situ sol-gel cross-linking.
- Relatively high thermal and thermooxidative stability.

Soluble poly(N-isopropylacrylamide-co-3-(trimethoxysilyl)propyl methacrylate), P(PNIPAAm-co-TMSPMA), copolymers with broad composition range, possessing condition and composition dependent LCST-type behavior, are successfully synthesized. Due to the hydrophobic character of the TMSPMA moieties, both the cloud point (TCP) and clearing point (TCL) decrease with increasing TMSPMA content, from 34.3 °C to 23.4 °C for the poly(N-isopropylacrylamide) homopolymer and copolymer with 11.1 mol% TMSPMA, respectively. Unexpected heating-cooling hysteresis with loss of transparency is found in the case of copolymers with higher TMSPMA contents due to in situ sol-gel cross-linking without any catalyst above the cloud point, which can be utilized for obtaining new smart hybrid materials. The copolymers possess closely the same, relatively high thermal and thermooxidative stabilities as that of PNIPAAm.

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