Temperature-sensitive smart polymer with self-controlled glass transition temperature

Abstract

We evaluated the effect of adding a small amount of poly(N-isopropylacrylamide) (PNIPAM), which is a temperature-sensitive polymer, on the glass transition temperature (Tg) of poly(vinyl acetate) (PVAc). The Tg of a blend comprising 5wt.% PNIPAM was affected by the ambient temperature; the Tg was low when the blend was stored at low temperatures and high when it was stored at high temperatures. This phenomenon can be attributed to the hydrophilic–hydrophobic transition of the PNIPAM. At low temperatures, the moisture content of the blend increased, resulting in a low Tg because of the plasticizing effect of water molecules on the PVAc. Because the material becomes soft at low temperatures, this unique property can be exploited in the design of smart materials.