Title: Copolymer hydrogels of 2-hydroxyethyl methacrylate with n-butyl methacrylate and cyclohexyl methacrylate: synthesis, characterization and uptake of water
Abstract: The bulk free radical copolymerizations of 2-hydroxyethyl methacrylate (HEMA) with n-butyl methacrylate (BMA) or cyclohexyl methacrylate (CHMA) were studied over the composition mole fraction interval of 0–1 for HEMA in the monomer feed. The 13C NMR (125 MHz) spectra of the copolymers were analysed to determine the copolymer composition and the stereochemical configuration of the copolymers. The terminal model reactivity ratios of HEMA and BMA were found to be rHEMA=1.73 and rBMA=0.65 and for HEMA and CHMA, rHEMA=1.26 and rCHMA=0.31. The BMA and CHMA homopolymers were found to be predominantly syndiotactic with isotacticity parameters of θBB=0.18 and θCC=0.19, respectively. The copolymers were also found to be predominantly syndiotactic, indicating a strong tendency for racemic additions of the monomers in the formation of the copolymers. The diffusion of water into cylinders of poly(HEMA-co-BMA) and poly(HEMA-co-CHMA) was studied over a range of copolymer compositions and was found to be Fickian. The diffusion coefficients of water at 37°C were determined from swelling measurements and were found to vary from 1.72×10−11 m2 s−1 for polyHEMA to 0.97×10−11 m2 s−1 for poly(HEMA-co-BMA) having a mole fraction FHEMA=0.80 and to 0.91×10−11 m2 s−1 for a poly(HEMA-co-CHMA) also having FHEMA=0.80. The mass of water absorbed at equilibrium relative to the mass of dry polymer varied from 58.8 for polyHEMA to 27.2% for poly(HEMA-co-BMA) having FHEMA=0.85 and to 21.3% for poly(HEMA-co-CHMA) having FHEMA=0.80.
Publication Year: 2000
Publication Date: 2000-02-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 59
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