Graft copolymerization onto starch. IV. Grafting of methyl methacrylate to granular native potato starch by manganic pyrophosphate initiation

Abstract

SynopsisA study has been made of graft copolymerization of methyl methacrylate onto native potato starch in aqueous slurry at 30°C. As Mn3+ concentration was increased from 0.15 X 10-3M to 1.0 X 10-3M, conversion of monomer to polymer and add-on of polymer to starch increased and frequency of grafts (anhydroglucose units per grafted chain) decreased sharply. The average molecular weights of the PMMA grafts also decreased in this range. At Mn3+ concentrations from 1.0 X 10-3M to 3.0 X 10-3M, only minor changes in grafting parameters were observed. When the amount of starch charged per batch was increased threefold, the add-on decreased sharply, the molecular weight increased slightly, and the conversion of MMA monomer to polymer remained almost constant. The increase in frequency of grafts (AGU/chain) was almost directly proportional to the increase in the amount of starch charged. In all cases the average molecular weights of grafts were of the order of lo6 and the grafting efficiencies high, normally greater than 85%. These results were compared with those previously obtained for grafting of acrylonitrile onto starch. They were interpreted in terms of initial (Mn3+)/(ACU) ratio, total number of radicals initiating grafting, and compatibility of methyl methacrylate monomer with poly(methy1 methacrylate) chains.

Preparation and characterization of amphiphilic starch nanocrystals

“…There are mainly two kinds of mechanism for the emulsion polymerization of starch‐ g ‐polystyrene nanocrystals. One is the grafting occurs by the polymerization of styrene induced by the free radical on the starch backbone, as reported by Mehrotra and Ranby 11. The other is that a growing chain free radical of polystyrene in a micelle is adsorbed onto starch surface and attached to an oxy radical at the surface.…”

On the Use of Starch in Emulsion Polymerizations

“…Monomer conversion (77-84%), AO (48-49%) and the molecular weight of grafts (33,000-430,000) all increased as the starch pre-treatment temperature was increased from 30-85°C [22]. Grafting efficiencies were generally higher with AN than MMA due to increased rates of termination with MMA [23]. When a methanol:water mixture was used as the solvent, the GE linearly increased to 100% as methanol:water ratio increased to 50:1 (v:v).…”

“…Biopolymers such as polysaccharides offer naturally occurring and sustainably grown materials to act as fillers or macromers as a substitute for synthetic, petroleum-based monomers in polymer formulations. Polysaccharides have been extensively studied and are among the most abundant, versatile, inexpensive and commercially utilized biopolymers [5,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32].…”

Graft copolymerization of granular starch maleate with acrylamide for enhancing grafting efficiency

“…Further studies pay much attention to the graft initiators. As a result, a lot of chemical initiators such as ferrous ammonium sulfate/hydrogen peroxide [12] , potassium persulfate/ sodium thiosulfate [13] , manganic pyrophosphate [14] , potassium permanganate [15,16] , and ceric ion [17,18] have been extensively studied and applied to the synthesis of starch graft copolymers. Moreover, starch state and reaction medium also infl uence the two parameters.…”