Graft copolymerization of vinyl monomers initiated by manganic sulfate–sulfuric acid

Singh, Harcharan; Thampy, R. T.; Chipalkatti, V.B.

doi:10.1002/pol.1965.100031226

Cited by 10 publications

(6 citation statements)

References 2 publications

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“…The formation of the initiating radicals by γ, β, or UV radiation is nonspecific and results in the formation of a significant amount of homopolymer. − Classical initiating systems for the chemical formation of starch radicals are permanganates in the presence of acids, − the Fenton agent, − and peroxodisulfates. − Large amounts of homopolymers are formed in all of these systems because the primary radicals, which are not bound to starch, also initiate homopolymerization. The unwanted side reactions can be suppressed by generating radicals with the help of Ce(IV) − or Mn(III), − but it is difficult to remove these metal ions from the colored products. However, even in this case, the formation of homopolymer cannot be excluded.…”

Section: Introductionmentioning

confidence: 99%

Cationic Polymer Grafted Starch from Nonsymmetrically Substituted Macroinitiators

et al. 2005

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The aim of this work was the synthesis of starch macroinitiators for cationic polymer grafted starches that: W are free of cationic homopolymer, and (ii) display a high degree of conversion of the cationic monomer. We show that this can be achieved by a free-radical polymerization reaction using the cationic monomer N-methaeryloyloxyethyl-N,N-dimethyl-N-benzylammonium chloride (XLADAM-BQ) and a new starch-based macroazoinitiator. For this purpose, the acid chloride of 4-tert-butylazo-4-cyanovaleric acid was synthesized and bound covalently to starch (predominantly in the C6 position) to form a nonsymmetrically substituted macroinitiator that was used to polymerize MADAM-BQ in aqueous media. Essentially no MADAM-BQ homopolymer was formed. The initiator decomposes thermally to starch radicals of high reactivity and low-molar mass radicals that do not initiate polymerization. The reason for the different reactivities of the radicals is presumably due to the nonsymmetric constitution of the starch-bound azo groups. The graft polymerization of MADAM-BQ in aqueous solution performs according to an ideal overall kinetic. The structure of the synthesized starch-graft-poly(MADAM-BQ) products is similar to that of block copolymers because of the low radical efficiency of the starch initiators in aqueous solution. Especially, starch substrates with a higher content of azo groups did not lead to graft products with shorter graft distances because the state of solution of these macroinitiators becomes worse and aggregation occurs with an increasing degree of substitution

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Section: Introductionmentioning

confidence: 99%

Cationic Polymer Grafted Starch from Nonsymmetrically Substituted Macroinitiators

et al. 2005

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“…Singh et al 3 have reported the use of Mn3+ ions as initiator for grafting to polysaccharides. Due to the instability and disproportionation of these ions in sulfuric acid media of low acidities4 according to the reaction (1) 2Mn3+ -Mn4+ + Mn2+ in grafting of vinyl monomers to amylose using the sulfate complex of Mn3+ ions.…”

Section: Introductionmentioning

confidence: 99%

Graft copolymerization onto starch. I. Complexes of Mn3 as initiators

Mehrotra

Rånby

1977

J. Appl. Polym. Sci.

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SynopsisAdvantages in using the pyrophosphate complex of trivalent manganese over the sulfate complex as initiator for graft copolymerization onto starch are discussed. The first successful attempts to graft copolymerize acrylonitrile, methyl methacrylate, and acrylamide to starch and starch derivatives are described using manganic pyrophosphate as initiator. Selective solvent extraction of the reaction products and very low conversions of monomer to homopolymer in absence of starch substrates provide evidence for high grafting efficiencies obtained with acrylonitrile and methyl methacrylate. With acrylamide as monomer, however, low grafting efficiencies and considerable amounts of homopolymer are obtained under the experimental conditions investigated. Reaction mechanisms responsible for initiation of graft copolymerization are discussed. These are (a) glycol cleavage in the anhydroglucose units by Mn3+ ions leading to formation of a radical, and (b) enolization and further oxidation of oxidized starch by Mn3+ ions also leading to radical species. Mechanisms are also proposed for homopolymerization through Mn"+ oxidation of enols which probably are formed by "vinylogous" addition of water molecules to acrylamide and methyl methacrylate.

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“…Singh et a1. 22 and Namasivayam et al 23 have reported that manganic sulfate in an excess of sulfuric acid may form an effective redox system for grafting of poly( methyl methacrylate) onto cellulose and poly(viny1 alcohol) (PVA). Recently, Nayudamma et al 24 have reported the Mn3+-initiated graft copolymerization of vinyl monomers onto collagen.…”

Section: Introductionmentioning

confidence: 98%

Polymerization of methyl methacrylate initiated by the redox system Mn3/thioglycollic acid

Samal

Suryanarayan²,

Panda³

et al. 1981

J. Appl. Polym. Sci.

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SynopsisThe kinetics of aqueous polymerization of methyl methacrylate initiated by the redox system Mn3+-thioglycollic acid was studied in sulfuric acid in the temperature range of 35-50°C, and the rates of polymerization R, and Mn3+ disappearance, etc., were measured. The effect of certain water-miscible organic solvents, neutral electrolytes, and complexing agents on the rates of polymerization has been investigated. A mechanism involving the formation of a complex between Mn"+ and thioglycollic acid whose decomposition yields the initiating free radical with the polymerization being terminated by the metal ion has been suggested.

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Graft copolymerization of vinyl monomers initiated by manganic sulfate–sulfuric acid

Cited by 10 publications

References 2 publications

Cationic Polymer Grafted Starch from Nonsymmetrically Substituted Macroinitiators

Cationic Polymer Grafted Starch from Nonsymmetrically Substituted Macroinitiators

Graft copolymerization onto starch. I. Complexes of Mn3 as initiators

Polymerization of methyl methacrylate initiated by the redox system Mn3/thioglycollic acid

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