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Investigation of the thermal aggregation in aqueous poly( N ‐isopropylacrylamide‐ co ‐itaconic acid) solutions
Author(s) -
Erbil Candan,
Akpınar F. Dilek,
Uyanık Nurseli
Publication year - 1999
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19991101)200:11<2448::aid-macp2448>3.0.co;2-1
Subject(s) - potassium persulfate , itaconic acid , chemistry , polymer chemistry , aqueous solution , poly(n isopropylacrylamide) , copolymer , polymerization , radical polymerization , cloud point , gel permeation chromatography , distilled water , nuclear chemistry , organic chemistry , polymer , chromatography
Copolymers of N ‐isopropylacrylamide (NIPAAM) and itaconic acid (IA) were prepared via free radical polymerisation using potassium persulfate (K 2 S 2 O 8 ) in distilled‐deionised water at 50°C in nitrogen atmosphere. The dependence of the aggregation process on pH and IA content and the copolymer composition were examined by means of UV‐VIS, FTIR, and 1 H NMR spectroscopy, gel permeation chromatography (GPC), and viscosity measurements. Cloud points of 0.5 wt.‐% aqueous solutions of the copolymers and of PNIPAAM were measured in the range of pH 1–9 and found to decrease with increasing NIPAAM content and decreasing pH. The differences in the phase transition temperatures were supposed to result from interactions between the isopropyl group and unionised carboxylic acid groups or electrostatic interactions between the carboxylate groups, depending on the pH and hydrophilic constituent content.