Temperature-induced phase transition of poly(N-n-propylacrylamide-co-butylmethacrylate-co-N,N-diethylaminoethyl methacrylate)

Terpolymers composed of N-n-propylacrylamide (NPAAm), butyl methacrylate (B MA), and N,N-diethylaminaethyl methacrylate (DEAEMA) were prepared in an at tempt to investigate the temperature-induced phase transition and its mecha nism. Poly(NPAAm) showed the lower critical solution temperature (LCST) aro und 24 degrees C in water. With the incorporation of DEAEMA with NPAAm, the LCST change was characterized by an initial increase. However, the LCST wa s shifted to the lower temperature at the later stage. This might be explai ned in terms of hydrophilic/hydrophobic contribution of DEAEMA to the LCST. The swelling behavior of copolymer gel in the various solvents and spin-la ttice relaxation time (T-1,) study by NMR strongly suggested the hydrophili c/hydrophobic contribution of DEAEMA to the LCST depending on the local env ironment. (C) 1999 John Wiley & Sons, Inc.