关键词: 构象变化, 阴离子共聚物, 粘度, 光谱法

Abstract: The pH induced conformational change of the binary anionic monomers and acrylamide terpolymer(P3A) composed of the non-ionic monomer acrylamide(AM), strong-acidic monomer 2-acrylamide-2-methylpropane-sulfonate(AMPS) and weak-acidic monomer(AA) were studied in dilute aqueous solution by viscosimetry and spectrometry. The results obtained show that the solution viscosity of P3A increases non monotonousily with pH values and a dramatic enhancement occurs in the range of pH 4～5, which is attributed to the rapid transition from compact to expanded state of the polymer chain. The intensity of viscosity changes between the two states is closely related with the fraction of AMPS and AA in the polymer. The pH dependence of the fluorescence intensity of pyrene probe in P3A solution shows a similar result as viscosity. At low pH the phase separation was observed in the solution of(P2AA) copolymer composed of single weak acidic unit(AA), but it does not occur in case of(P3A) polymers containing strong acidic unit(AMPS). Therefore, different acid-resistant and pH-responsive P3A polymers can be constructed by controlling the fraction of two ions units(AMPS and AA) in polymer chains as desired for practical application.

Key words: conformational change, anionic polymer, viscosity, spectrometry