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Acrylonitrile graft copolymerization of casein proteins for enhanced solubility and thermal properties
Author(s) -
Dong Qingzhi,
Hsieh YouLo
Publication year - 2000
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 - 10.1002/1097-4628(20000912)77:11<2543::aid-app23>3.0.co;2-b
Subject(s) - acrylonitrile , copolymer , chemistry , polymer chemistry , solubility , grafting , triethanolamine , casein , potassium persulfate , polymerization , polymer , organic chemistry , analytical chemistry (journal)
Casein proteins are soluble in 5% aq. ethanolamine, triehtylamine, and triethanolamine, but insoluble in organic solvents. Graft copolymerization of casein (40 g/L) with acrylonitrile (AN) was carried out in 5% w/v aq. triethanolamine at 60°C using potassium persulfate K 2 S 2 O 8 as an initiator. Percent grafting and grafting efficiency increased with increasing initiator concentrations (up to 1.7 × 10 −2 mole L −1 ) and reaction times, but decreasing [ M ]/[ I ] ratios. Fourier transform IR spectra confirmed the formation of the acrylonitrile‐grafted‐casein (AN‐g‐casein) copolymers. Under the reaction conditions studied, the grafted PAN side chains were characterized by gel permeation chromatography to have M n between 1.58 and 5.88 × 10 4 dalton and polydispersities between 2.6 and 4.5. The AN‐g‐casein copolymers behaved more like a PAN homopolymer in terms of their thermal properties and solubilities. The decomposition temperatures of AN‐g‐casein copolymers were between 255 and 273°C, closer to the T d of the PAN homopolymer (275°C) and significantly higher than that of casein (180°C). The AN‐g‐casein copolymers are soluble in 50% aq. NaSCN and ZnCl 2 , but are insoluble in 32:28:40 wt % CaCl 2 /CH 3 CH 2 OH/H 2 O like PAN and dimethylformamide‐like casein. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2543–2551, 2000