Grafting of methyl methacrylate onto collagen initiated by tributylborane

The graft copolymerization of methyl methacrylate onto collagen initiated by tributylborane was investigated in aqueous medium. The total conversion, percentage of grafting and efficiency of grafting increased with increasing collagen content. The optimum conditions on the percentage of grafting and efficiency of grafting were determined by varying initiator concentration, monomer concentration, and polymerization temperature. The grafting onto denaturated collagen was also studied. It has been suggested that the grafting onto collagen proceeds by a radical mechanism via a complex of TBB and hydrated collagen.     

Grafting of methyl methacrylate onto silk fibers initiated by tri-n-butylborane

Structural characteristics of the methyl methacrylate (MMA)-grafted silk fibers using tri-n-butylborane as an initiator were analyzed by infrared spectroscopy and differential scanning calorimetry (DSC), and their refractive index and tensile properties were measured. Graft polymerization was promoted by FeCl₃ pretreatment of the silk. The graft yield reached a maximum by the immersion in 4% FeCl₃ solution for 1 min at 25°C. The infrared spectrum of poly(MMA)-grafted silk fibers showed overlapped absorption bands of silk fibroin with the β structure and of the grafted MMA polymer. A grafted silk fiber with graft yield of more than 140% exhibited two endothermic peaks at 321°C and 396°C on the DSC curve, attributed to the thermal decomposition of silk fibroin and grafted poly(MMA) chain, respectively. Refractive index measurements suggested that the molecular orientation and the crystallinity of the silk fiber decreased with increasing graft yield. Electron photomicrographs showed that silk was coated by grafted PMMA. The tensile strength of the grafted silk decreased rapidly by the grafting even at a lower level.     

Grafting of methyl methacrylate onto guar gum by hydrogen peroxide initiation

Graft copolymerization of methyl methacrylate (MMA) onto guar gum (GG) in aqueous slurry has been carried out using hydrogen peroxide (H₂O₂) as initiator. The copolymers were characterized by infrared spectroscopy. The grafting parameters like percent grafting, grafting efficiency, percent add-on, and the grafting frequency were determined, and the effect of reaction time, concentration of initiator, and [GG]/[MMA] ratios on the grafting parameters have been discussed. The decrease in % add-on at increasing concentration of H₂O₂ indicated enhancement in the rate of homopolymerization of methyl methacrylate.     

Graft copolymerization of methyl methacrylate upon gelatin initiated by benzoyl peroxide in aqueous medium

The graft copolymerization of methyl methacrylate upon gelatin was studied using benzoyl peroxide as an organic initiator in aqueous medium. The grafting reactions were carried out within the 65–90°C temperature range, and the effect of monomer and initiator concentrations on the graft yield were also investigated. The maximum graft yield was obtained at a benzoyl peroxide concentration of 0.20 × 10⁻² mol/L and the optimum temperature was 80°C. Thermogravimetric analysis showed that the thermal stability of gelatin increased as a result of grafting. Further, such changes in the properties of methyl methacrylate‐grafted gelatin as density, moisture regain, and water uptake were also determined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1547–1556, 1999     

Effects of some unsaturated nitrogen-heterocycles on the polymerization of methyl methacrylate initiated by benzoyl peroxide

Summary The rate of polymerization at 60°C of methyl methacrylate initiated by benzoyl peroxide is almost unaffected by the presence of a small amount of 4-styrylpyridazine, 1-(2-pyridyl)-2-(4-pyridyl)ethylene or 2,6-distyrylpyridine. Examination of polymers made using peroxide suitably labeled with carbon-14 and tritium shows that these additives increase the ratio of benzcate to phenyl end-groups derived from the initiator. This effect arises because the additives are effective in capturing the benzoyloxy radical; in this respect, they are however considerably less reactive than the corresponding compounds containing groups derived from benzene in place of the nitrogen heterocycles.     

Photo-induced graft copolymerization of methyl methacrylate onto cellulose containing benzoyl xanthate chromophore

Summary Cellulose is conveniently functionalized to the corresponding S-benzoyl cellulose xanthate. Photolysis of S-benzoyl cellulose xanthate in presence of methyl methacrylate (MMA) initiated graft copolymerization which was confirmed by different analytical techniques.Document No. RRLT-PRU-25     

Grafting of methyl methacrylate onto sodium alginate initiated by potassium ditelluratoargentate(III)

Sodium alginate (SA) was graft‐copolymerized with methyl methacrylate in an alkali aqueous solution with potassium ditelluratoargentate(III) (DTA) as the initiator. Graft copolymers with both a high grafting efficiency (>90%) and a high percentage of grafting were obtained, which indicated that the DTA–SA redox pair was an efficient initiator for this grafting. The grafting parameters, including total conversion, grafting efficiency, and percentage grafting, were evaluated comparatively. The dependence of these parameters on temperature and time, monomer concentration, initiator concentration, and SA backbone concentration was also investigated. The overall activation energy of this grafting was calculated as 37.50 kJ/mol. Proof of grafting was obtained from gravimetric analysis and IR spectra. A tentative mechanism involving a two‐step, single‐electron‐transfer process of DTA is proposed to explain the generation of radicals and the initiation of grafting. Some basic properties of the grafted copolymer were studied by instrumental analyses, including thermogravimetry, X‐ray diffraction, and scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1688–1694, 2005     

Grafting of acrylonitrile onto cellulose initiated by ceric ion

Acrylonitrile was grafted onto cellulose with the use of ceric salt as initiator and the grafting was found to be maximum at 0.6N acid concentration. The effect of monomer and initiator concentration on the extent of grafting was studied. A new method for quantitative estimation of extent of grafting on cellulose was developed and its validity was established. The grafted samples with 20% increase in weight were found to be highly resistant to microorganisms.     

Grafting of partially hydrolysed poly(methyl methacrylate) onto mesylated cellulose acetate

A new synthetic route to cellulose graft polymers by nucleophilic displacement of mesylate groups from mesyl cellulose acetate (MCA) by the polystyrylcarboxylate anion has been recently reported by us. This approach to cellulosic graft polymers overcomes the drawbacks of the radical polymerization methods and allows for precise control of parameters such as the molecular weight and molecular weight distribution of the grafted side chains, higher degree of substitution on the cellulose backbone, the number and nature of grafted side chains and overall better control and reproducibility of the grafting process. In this report, partially hydrolysed poly(methyl methacrylate) was successfully grafted on to mesylated cellulose acetate in excellent yields by nucleophilic displacement of mesylate groups in less than 60 min at 75°C.     

Grafting vinyl monomers onto cellulose. I. Graft copolymerization of methyl methacrylate onto cellulose using quinquevalent vanadium ion

Graft copolymerization of methyl methacrylate on cellulosic materials with the use of quinquevalent vanadium as an initiator was studied. Increase of V⁵⁺ion concentration up to 0.0025 mole/liter increases graft yield, and with further increase of the initiator the graft yield decreases. The graft yield increases with increase of monomer concentration. The increase of acid concentration is accompanied by decrease of graft yield. A measurable increase in graft yield was observed with increase in temperature from 65 to 75°C. The graft yield is medium and substrate dependent. A suitable kinetic scheme has been pictured and a rate equation has been derived.     

Grafting of ethyl acrylate onto monofilament polyester fibers using benzoyl peroxide

Ethyl acrylate was grafted onto monofilament poly(ethylene terephthalate) fibers using benzoyl peroxide as a chemical initiator. Breaking tenacity and densities of grafted fibers decreased while breaking elongation increased with the graft yield. Scanning electron micrographs showed that the fiber geometry and its diameter were not affected by grafting. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1701–1705, 1998     

Grafting vinyl monomers onto cellulose. IV. Graft copolymerization of methyl methacrylate onto modified cellulose using peroxydiphosphate as the initiator

The graft copolymerization of methyl methacrylate onto modified cellulose was studied at 60° causing peroxydiphosphate as the initiator. The rate of grafting in case of different modified cellulose was determined by varying peroxydiphosphate, monomer, nature of substrate, and temperature. The molecular weight of the isolated polymer has been determined, and the mechanism of grafting is discussed.     

Hexavalent-chromium-initiated graft copolymerization of methyl methacrylate onto cellulose

Graft copolymerization of methyl methacrylate (MMA) onto cotton–cellulose has been carried out using hexavalent chromium Cr(VI) as initiator. Aqueous-methanolic solution of perchloric acid has been chosen as the reaction medium. The effect of monomer, initiator, acid, reaction medium, and temperature on the graft percentage has been found out. The reactions have also been carried out in the presence of polymerization, inhibitors, and retarders, such as hydroquinone and transition metal salts like CuSO₄, FeCl₃, etc. The grafted samples, after exhaustive separation of homopolymers and purification, were subjected to various chemical, mechanical, and thermal testings. The results of various analyses have been compared with the reference, and the improvement in the graft has been evaluated. A suitable mechanism for the grafting processes has been suggested, in accordance with the experimental results.     

Grafting onto wool fibers: Graft copolymerization of methyl methacrylate onto wool fibers initiated by KHSO5/Fe(III) couple

Graft copolymerization of methyl methacrylate (MMA) onto wool fibers has been carried out in an aqueous medium under deaerated condition initiated by potassium monopersulphate (KHSO₅/Fe(III) system, at varying concentration of the reactants and temperature. The effect of various salts and organic solvents on the extent of grafting has also been studied. Maximum graft percentage of 210.8% was obtained in 4 h at 40°C with the concentration of MMA (0.46 M), KHSO₅ (0.0195 M), Fe(III) (1.25 × 10^?4 M) in the presence of 50% formic acid. Various improved properties of the grafts have been studied and compared with the parent fiber.     

Grafting of 2-hydroxyethyl methacrylate and methyl methacrylate onto chrome tanned collagen fibers

Grafting of 2-hydroxyethyl methacrylate and methyl methacrylate onto chrome tanned collagen fibers, initiated by the bisulfite/pesulfate redox system, has been investigated. Using the method of statistical planning of experiments, regression equations have been obtained describing the effects of the monomers concentration and the composition of the initiating system on the monomers conversion, degree of grafting and on physical properties of grafted collagen. The relationship between the polyacrylate content in the composites prepared and their swelling ability, water absorption capacity, and the tensile strength is discussed.