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pH–thermoreversible hydrogels. II. Synthesis and swelling behaviors of N‐isopropylacrylamide‐ co ‐acrylic acid‐ co ‐sodium acrylate hydrogels
Author(s) -
Lee WenFu,
Shieh ChihHsuan
Publication year - 1999
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/(sici)1097-4628(19990906)73:10<1955::aid-app15>3.0.co;2-8
Subject(s) - self healing hydrogels , swelling , acrylic acid , poly(n isopropylacrylamide) , acrylate , polymer chemistry , materials science , sodium , chemical engineering , chemistry , copolymer , composite material , organic chemistry , polymer , engineering
A series of pH–thermoreversible hydrogels are prepared from the three molar ratios of N ‐isopropylacrylamide (NIPAAm) and acrylic acid neutralized 50 mol % by sodium hydroxide (SA50) and N , N ′‐methylene bisacrylamide (NMBA). The influence of the environmental conditions, such as temperature and pH values, on the swelling behavior of these copolymeric gels is also investigated in this article. Results show that the hydrogels bearing negative charges exhibit different equilibrium swelling ratios under various pH media. The pH sensitivities of these gels also strongly depend on the molar ratio of SA50 in the copolymeric gels; thus, the more the SA50 content, the higher the gel pH sensitivity. These hydrogels exhibited thermosensitivity demonstrating a larger change of the equilibrium swelling ratio in aqueous media under temperature changes. An overshooting phenomenon is observed from the gel swelling kinetics under high‐temperature conditions. The said hydrogels are also used to investigate the release of model drugs in this study. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1955–1967, 1999