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Thermoreversible behaviour in water of chemically crosslinked poly(2‐methoxyethylacrylate‐ co‐N,N ‐dimethylacrylamide)
Author(s) -
ElEjmi Ali A. S.,
Huglin Malcolm B.
Publication year - 1997
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199711)44:3<277::aid-pi864>3.0.co;2-l
Subject(s) - copolymer , materials science , polymer chemistry , swelling , chemical engineering , lower critical solution temperature , aqueous solution , dispersity , self healing hydrogels , acrylate , polymerization , polymer , chemistry , composite material , engineering
Hydrogels of poly( N,N ‐dimethylacrylamide‐ co ‐2‐methoxyethyl‐acrylate) have been synthesized by crosslinking copolymerization, and the dimensions of swollen films at swelling equilibrium in water have been measured over a range of temperature ( T ). At 4°C, transparency and maximum water content are exhibited. On heating, deswelling occurs and loss of transparency develops at 35°C, opacity and deswelling being complete at 50°C. The process is reversible and the lower critical swelling temperature ( T c ) is found to be 38±2°C. Although water content at any temperature increases with decreasing content of crosslinker, the latter has no discernible influence on T c . Microgels of the same copolymer have also been prepared by dispersion polymerization in 2‐propanol. After dialysis in water, the diameters ( D ) of the microbeads in dilute aqueous suspension were measured by dynamic light scattering. D decreased from 2·3μm at 10°C to 0·2μm at T ≥50°C, and T c was located at 36±2°C. Optical microscopy revealed the spherical nature and polydispersity of the beads, the dimensions of which lay in the range 7μm> D >0·8μm. These copolymers were sticky in both the dry and the swollen states, which may be advantageous for coating to an inert substrate for application as a possible separation device based on thermoreversible swelling. ©1997 SCI