PVA graft copolymer

By living cationic polymerization, our group has investigated the synthesis of polymers of various shapes including gradient copolymers,PVA graft copolymers,and end-functional polymers for the modification of liposomes to provide controlled release of drugs. 

Preparation of PVA graft copolymers by living cationic polymerization. Scheme 2.28... 

Porous membranes with selective permeabiUty to organic solvents have been prepared by the extraction of latex films prepared with moderate ratios of PVA—PVAc graft copolymer fractions. The extracted films are made up of a composite of spherical cells of PVA, PVAc microgel, and PVA—PVAc graft copolymers (113). 

There has been a conventional sense that the PVAc latexes prepared in the presence of PVA as a protective colloid contain the graft copolymer of PVA and PVAc, so that PVAc particles in the dried latex film are not extracted at a high ratio with solvents. In this Chapter, it has been defined without an influence by the usual sense that the porous PVA-PVAc composite can be prepared from the PVAc latex film with acetone extraction. The porous film consists of the spherical cells of PVA... 

The comparison of the 2D plot of a graft copolymer with the 2D plot of the precursor PEO shows clearly that the graft copolymer sample does not contain any free PEO. This result was also confirmed by MALDI-TOF mass spectrometry. Next to the requirement of being PEO free, the PEO-g-PVA copolymers showed a good combination of film-forming properties, a fast dissolution, and a low solution viscosity in water. The phase separated morphology, as demonstrated by TEM, DSC, DMTA, and WAXS experiments, provided the PEO-g-PVA copolymers with relatively constant mechanical properties. 

A strain of yeast and a strain of bacterium were co-immobilized to fabricate a biochemical oxygen demand (BOD) sensor based on sol-gel derived composite materials97. This novel type of biosensor was developed for water monitoring and was used to determine the BOD values of OECD synthetic wastewater, domestic wastewater, and lake waters. The microorganisms Trichosporon cutaneum and Bacillus subtilis were coimmobilized in the sol-gel composite material, which was composed of silica and the grafting copolymer of poly (vinyl alcohol) and 4-vinylpyridine (PVA-g-P(4-VP)). 

On the other hand, similar alternate extraction gives an erroneous result for the reaction product obtained by the grafting of styrene onto PVA (extractions 1 —7 in Fig. 10), unless the PVA part in the product is acetylated to PVAc. The acetylation is carried out for the residue taken out in the middle stage of the 2nd extraction (at A in Fig. 10) and the PVAc and PS are extracted with methanol and cyclohexane, respectively. The result is also given in Fig. 10 (broken line). As can be seen, the acetylation leads to a successful removal of the homopolymers. The removal of the homopolymers from the unacetylated reaction product appears to be accomplished at the 7th extraction, but extraction 3 for the acetylated sample indicates that the unreacted PVA still remains unextracted in the 7th extraction residue by an amount nearly equal to that of the PVA component in the graft copolymer. 

The MMA homopolymer and the unreacted PVA are removed from the reaction product by the selective extraction method. The grafted branch PMMA is separated from the backbone by oxidative cleavage of all 1,2-glycols of PVA (about 2 mole%)29 Molar masses of the isolated graft copolymers and the separated branches are osmo-metrically determined, after acetylation of hydroxyl groups in benzene. The chemical composition of the graft copolymers is determined from the saponification value of the acetylated sample. 

The PVA-PEG graft copolymer Kollicoat IR is the new instant-release, aqueous coating polymer from BASF. Due to its low viscosity and excellent mechanical properties, it permits solid content of up to 30% and leads to fine and smooth tablet film coatings. 

Strictly speaking, studies on graft copolymerization should always be accompanied by the characterization of the graft copolymer formed at least a determination of the yield of the graft copolymer. If the characterization is not performed at ail, one may claim that the grafting product might be merely a mixture of two homopolymers. We have demonstrated that the wei t increase of PVA films by a conventional graft copolymerization of MMA is mostly attributed to the MMA homopoly-... 

Stretched PVA-methyl acrylate graft copolymers for moisture-shrinkable... 

Muschert, S., Siepmann, F., Leclercq, B., Siepmann, J. Dynamic and static curing of ethylceUulose PVA-PEG graft copolymer film coatings. Eur. J. Pharm. Biopharm. 2011, 78(3), 455-461. 

Koerber, M., Hoffart, V., Walther, M., Macrae, R.J., Bodmeier, R. Effect of unconventional curing conditions and storage on pellets coated with Aquacoat ECD. Drug Dev. Ind. Pharm. 2010, 36(2), 190-199. Muschert, S., Siepmann, R, Leclercq, B., Carlin, B., Siepmann, J. Simulated food effects on drug release from ethylcellulose PVA-PEG graft copolymer-coated pellets. Drug Dev. Ind. Pharm. 2010, 36(2), 173-179. 

In the present contribution an investigation on the biodegradation of blends and graft copolymers of PHB of both natural and synthetic origin and PVA/PVAc blends is reported. The evaluation of the effects of each component in blends and copolymers on both the overall extent of biodegradation and the biodegradation of counterparts, was investigated in aqueous media and in soil by means of respirometric tests. 

A preliminary investigation on the biodegradation of graft copolymer and blends of PVA with chemically synthesized atactic PHB was carried out in an aqueous medium by using a PVA-degrading selected bacterial culture as inoculum. 

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