Synthesis and Characterization of Thermosensitive P(NIPAAm--AAc)-Grafted Silica Nanocomposites for Smart Architectural Coatings.

In this study, a new class of thermosensitive poly(-isopropylacrylamide)--poly(acrylic acid) (P(NIPAAm--AAc))-grafted modified silica (m-silica) nanocomposites was prepared using a sol-gel technique. The addition of silica to P(NIPAAm--AAc) copolymer hydrogel has the potential to open up new applications in the development of thermosensitive building materials by leveraging the favorable thermal characteristics of P(NIPAAm--AAc). The silica was prepared using 3-aminopropyltriethoxysilane and 4,4'-azobis(4-cyanovaleric acid) to form the m-silica powder, which increased the adhesion between the organic and inorganic hybrid materials. The P(NIPAAm--AAc) copolymer hydrogel was mixed with the m-silica to form the P(NIPAAm--AAc)-grafted m-silica nanocomposites. Scanning electron microscopy, X-ray diffraction analysis, thermogravimetric analysis, Fourier-transform infrared spectroscopy, and thermosensitive measurement were conducted to evaluate the structure and water-holding capacity of the nanocomposites. The results indicated that the P(NIPAAm--AAc)-grafted m-silica nanocomposites could retain water for more than 300 min at temperatures higher than the lower critical solution temperature. The P(NIPAAm--AAc)-grafted m-silica nanocomposites exhibited favorable thermosensitive properties and may therefore be applied in smart architectural coatings.