Template copolymerisation of N-isopropylacrylamide with a cationic monomer: influence of the template on the solution properties of the product

A copolymer containing 91 mol% N-isopropylacrylamide (NIPAM) units and 9 mol% N,N-(dimethylaminopropyl)methacrylamide (MADAP) units, copolymer II, was prepared using polyacrylate chains as a template for the positively charged MADAP units. The properties of this product were compared to the properties of a similar copolymer (copolymer I) prepared in the absence of the template. The molar mass of copolymer II was found much higher than that of copolymer I. Moreover, the cloud point of copolymer II is closer to the cloud point of the homopolymer poly(N-isopropylacrylamide) at various pH conditions, indicating that copolymer II contains longer NIPAM-sequences than copolymer I. This explanation is further supported by the fact that copolymer II forms stronger, more compact and more hydrophobic hydrogen-bonding interpolymer complexes with polyacrylic acid at low pH, as it was revealed by viscometry, fluorescence and turbidity studies.