Water solution properties of hydrophobically modified poly(N-isopropylacrylamides)

To-study the;water solution properties of hydrophobically modified poly(N-isopropylacrylamides), the copolymers of NIPAM and a series of acrylic ester and cholesteryl acrylate were synthesized. The surface activity and micelle behavior of the copolymers in aqueous solution. were determined by surface tension:methods. Simultaneously,:the Lower Critical Solution Temperature (LCST) of the copolymers was studied by fluorescence probe method. Results shows that the LCSTs of the copolymers have no obvious change with the change of the alkyl length of acrylic ester and the molar ratios of acrylic ester for the copolymers, but they are all lower than the homopolymer of Poly (N-isopropylacrylamide) (PNIPAM). The microviscosity of the copolymers in aqueous solution was studied by fluorescence polarization. Results show that their microviscosity do not change with the change of the alkyl length of acrylic ester and the. molar ratios of acrylic ester for the copolymers. It indicates that at room temperature the copolymers can almost form the identical micellar structure.