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Phase behavior and self‐assembly of poly[ N ‐vinylformamide‐ co ‐(acrylic acid)] copolymers under highly acidic conditions
Author(s) -
Chen Qiang,
Liu Xiaoguang,
Xu Kun,
Song Chunlei,
Zhang Wende,
Wang Pixin
Publication year - 2008
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.28271
Subject(s) - copolymer , acrylic acid , formamide , aqueous solution , polymer chemistry , chemistry , hydrochloric acid , protonation , polymerization , particle size , chemical engineering , phase (matter) , salt (chemistry) , inorganic chemistry , organic chemistry , polymer , ion , engineering
Copolymers of N ‐vinylformamide and acrylic acid were synthesized by conventional aqueous free‐radical polymerization. The phase behavior of the copolymer solutions was investigated through the addition of hydrochloric acid and the variation of the temperature. With a moderate content of N ‐vinylformamide, the copolymers showed complex phase behaviors. Under low‐acidity conditions, a suspending liquid was formed, whereas under high‐acidity conditions, the random copolymers could assemble into round nanoparticles with a broad particle size distribution. When the temperature was reduced, a much less cloudy solution that contained nanoparticles became a milk‐like suspending liquid, and this temperature‐responsive phenomenon was reversible. This indicated that the formamide group was protonated under highly acidic conditions; the repulsive electrostatic forces compelled the aggregates to disperse. The amount of salt and excess acid influenced the particle size as well as the temperature‐responsive behavior of the copolymers under highly acidic conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008