EFFECT OF POLYMER COMPLEX-FORMATION ON THE CLOUD-POINT OF POLY(ISOPROPYL ACRYLAMIDE) (PNIPAAM) IN THE POLY(NIPAAM-CO-ACRYLIC ACID) - POLYELECTROLYTE COMPLEX BETWEEN POLY(ACRYLIC ACID) AND POLY(ALLYLAMINE)

A series of pH/temperature-sensitive polymers which contain both tempe rature and pH-sensitive components were synthesized by copolymerizing N-isopropyl acrylamide (NIPAAm) and acrylic acid (AAc). The influence of poly(allylamine) (PAA) as the polyelectrolyte on the lower critical solution temperature (LCST) of pH/temperature-sensitive polymers was investigated in the pH range of 2-12. The LCSTs of PNIPAAm/water in P( NIPAAm-co-AAc) were determined by cloud-point measurements. The LCSTs of PNIPAAm/water in the copolymers were strongly affected by the pH, t he presence of polyelectrolyte solute and AAc content in the P(NIPAAm- co-AAc). The polyelectrolyte complex between P(NIPAAm-co-AAc) and PAA was formed from the pK(a), of PAAc to the pK(b) of PAA. Also, the LCST s of the PNIPAAm in the copolymers were dependent on the charge densit y of the PAAc and concentration of the PAA. (C) 1997 Elsevier Science Ltd.