Efficiency and frequency of grafting of methyl methacrylate to granular corn starch

Abstract

PMMA content of graft copolymers with granular starch can be determined by acid hydrolysis with sufficient precision to allow reasonable estimates of efficiency and frequency of grafting. Preparation of the graft copolymer by initiation of methyl methacrylate with hydrogen peroxide and activators results in products containing long PMMA side chains attached to the starch at very infrequent intervals, but the length and frequency of attachment can be varied considerably by changes in the ratios of reactants. The highest frequency achieved was with PMMA of number‐average molecular weight of about 30,000, attached at a frequency of one chain per 230–250 glucose units in the starch. Under the more favorable conditions, oxidized starch yielded product of significantly more frequent grafting than did unmodified starch. Gradual addition of monomer, initiator, and activator to the starch slurry gave slightly higher frequency of grafting than did complete addition of all reactants at the start of the polymerization.

Synthesis of Temperature-Sensitive Poly(N-isopropylacrylamide) Hydrogel with Improved Surface Property

“…Unmodified corn starch was pretreated by the procedure of Brockway (13). Corn starch samples were successively extracted six times with refluxing 4 : 1 methanol-water to be defatted and then distilled water was used to wash the starch five times at room temperature (20 • C) to remove methanol.…”

Grafting of poly(vinyl acetate) to granular corn starch

“…of reflux in 1 N HC1 (l), but not after 6 hr. (2). A more significant factor, however, especially with respect to the gradual dissolving of the PVAc itself in refluxing HC1, is the probability that the product of Walrath et al was crosslinked.…”

Graft polymerization of acrylic acid onto corn starch in aqueous isopropanol solution

“…The graft reactions of methyl methacrylate, acrylonitrile, ethyl acrylate, acrylamide or acrylic acid onto corn starch in the presence of ceric or manganese ions were carried out at temperatures below 60 8 C; the values of conversion and efficiency in the reactions using well swollen corn starch or a hydrophobic monomer like methyl methacrylate were high, whereas those in the reactions using poorly swollen corn starch or hydrophilic monomers like acrylamide and acrylic acid were relatively low [15][16][17][18][19][20][21][22][23][24][25][26][27] . In the grafting reaction of AA onto corn starch, inhomogeneous products with low grafting efficiency were obtained by using Fenton's reagent (a mixture of hydrogen peroxide and ferric ions in water) as an initiator at temperatures below 40 8 C 15,18,19) . Similar products were obtained by using ammonium ceric sulfate/nitrate or manganic pyrophosphate as the initiator [20][21][22][23][24] .…”