Preparation of Thermosensitive Poly(N-isopropylacrylamide) (PNIPAM) by Radiation Polymerization of N-isopropylacrylamide in Solution State

Poly(N-isopropylacrylamide) (PNIPAM), a typical thermosensitive polymer was prepared by the radiation induced polymerization from solutions of (N-isopropylacrylamide) dissolved in different solvents in air and nitrogen. This process can applied to improve the application of the obtained PNIPAM because it reduces the use of chemical additives, which usually contaminate the product. The degree of polymerization and the molecular properties of PNIPAM homopolymer were studied by radiation conditions. The average number molecular weight of PNIPAAm increased at low radiation dose and seemed to reduce at dose higher than 30 kGy. The PNIPAM samples showed thermosensitivity with the lower critical solution temperature (LCST) at around 31.5oC. These results also indicated that PNIPAM has rather high thermo stability. (author)