Swelling kinetic study of poly(methyl vinyl ether-co-maleic acid) hydrogels as vehicle candidates for drug delivery
This review highlights recent progress in the synthesis and application of vinyl ethers (VEs) as monomers for modern homo- and co-polymerization processes. VEs can be easily prepared using a number of traditional synthetic protocols including a more sustainable and straightforward manner by reacting gaseous acetylene or calcium carbide with alcohols. The remarkably tunable chemistry of VEs allows designing and obtaining polymers with well-defined structures and controllable properties. Both VE homopolymerization and copolymerization systems are considered, and specific emphasis is given to the novel initiating systems and to the methods of stereocontrol.
The composition of chlorophyll-precursor pigments, particularly the contents of
Both epoxides and vinyl ethers can be polymerized cationically albeit through different intermediates. However, in the case of epoxide-vinyl ether mixtures the exact mechanism of cationically initiated polymerization is unclear. Thus, although vinyl ethers can be used as reactive diluents for epoxides it is uncertain how they would affect their reactivity. Cationic photocuring of diepoxides has many industrial applications. Better understanding of the photopolymerization of epoxy-vinyl ether mixtures can lead to new applications of cationically photocured systems. In this work, photo-DSC and real-time Fourier Transform Infrared Spectroscopy (RT-FTIR) were used to study cationic photopolymerization of diepoxides and vinyl ethers. In the case of mixtures of aromatic epoxides with tri(ethylene glycol) divinyl ether, TEGDVE, photo-DSC measurements revealed a greatly reduced reactivity in comparison to the homopolymerizations and suggested the lack of copolymerization between aromatic epoxides and TEGDVE. On the other hand, for mixtures of 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate, ECH, with TEGDVE the results indicated high reactivity of the blends. The polymerization mechanism might include copolymerization. To examine this mechanism, mixtures of the ECH with a tri(ethylene glycol) mono-vinyl ether, TEGMVE, were studied by both photo-DSC and RT-FTIR. Principal component analysis (PCA) proved to be an efficient tool in analyzing a large matrix of the spectral data from the polymerization system. PCA was able to provide insight into the reasons for the differences among replicated experiments with the same composition ratio and supported the hypothesis of copolymerization in the ECH/TEGMVE system. Thus, blends of cycloaliphatic epoxides and vinyl ethers seem to have a great potential for applications in high-productivity industrial photopolymerization processes.
Vinyl acetate is an organic compound with the formula CH3CO2CH=CH2. This colorless liquid is the precursor to polyvinyl acetate, an important industrial polymer.[3]
The worldwide production capacity of
This review highlights recent progress in the synthesis and application of vinyl ethers (VEs) as monomers for modern homo- and co-polymerization processes. VEs can be easily prepared using a number of traditional synthetic protocols including a more sustainable and straightforward manner by reacting gaseous acetylene or calcium carbide with alcohols. The remarkably tunable chemistry of VEs allows designing and obtaining polymers with well-defined structures and controllable properties. Both VE homopolymerization and copolymerization systems are considered, and specific emphasis is given to the novel initiating systems and to the methods of stereocontrol.
The composition of chlorophyll-precursor pigments, particularly the contents of
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, in etiolated tissues of higher plants were determined by polyethylene-column HPLC (Y. Shioi, S. I. Beale [1987] Anal Biochem 162: 493-499), which enables the complete separation of these pigments. DV-Pchlide was ubiquitous in etiolated tissue of higher plants. From the analyses of 24 plant species belonging to 17 different families, it was shown that the concentration of DV-Pchlide was strongly dependent on the plant species and the age of the plants. The ratio of DV-Pchlide to MV-Pchlide in high DV-Pchlide plants such as cucumber and leaf mustard decreased sharply with increasing age. Levels of DV-Pchlide in Gramineae plants were considerably lower at all ages compared with those of other plants. Etiolated tissues of higher plants such as barley and corn were, therefore, good sources of MV-Pchlide. Absorption spectra of the purified MV- and DV-Pchlides in ether are presented and compared.Both epoxides and vinyl ethers can be polymerized cationically albeit through different intermediates. However, in the case of epoxide-vinyl ether mixtures the exact mechanism of cationically initiated polymerization is unclear. Thus, although vinyl ethers can be used as reactive diluents for epoxides it is uncertain how they would affect their reactivity. Cationic photocuring of diepoxides has many industrial applications. Better understanding of the photopolymerization of epoxy-vinyl ether mixtures can lead to new applications of cationically photocured systems. In this work, photo-DSC and real-time Fourier Transform Infrared Spectroscopy (RT-FTIR) were used to study cationic photopolymerization of diepoxides and vinyl ethers. In the case of mixtures of aromatic epoxides with tri(ethylene glycol) divinyl ether, TEGDVE, photo-DSC measurements revealed a greatly reduced reactivity in comparison to the homopolymerizations and suggested the lack of copolymerization between aromatic epoxides and TEGDVE. On the other hand, for mixtures of 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate, ECH, with TEGDVE the results indicated high reactivity of the blends. The polymerization mechanism might include copolymerization. To examine this mechanism, mixtures of the ECH with a tri(ethylene glycol) mono-vinyl ether, TEGMVE, were studied by both photo-DSC and RT-FTIR. Principal component analysis (PCA) proved to be an efficient tool in analyzing a large matrix of the spectral data from the polymerization system. PCA was able to provide insight into the reasons for the differences among replicated experiments with the same composition ratio and supported the hypothesis of copolymerization in the ECH/TEGMVE system. Thus, blends of cycloaliphatic epoxides and vinyl ethers seem to have a great potential for applications in high-productivity industrial photopolymerization processes.
Vinyl acetate is an organic compound with the formula CH3CO2CH=CH2. This colorless liquid is the precursor to polyvinyl acetate, an important industrial polymer.[3]
The worldwide production capacity of
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was estimated at 6,969,000 tonnes/year in 2007, with most capacity concentrated in the United States (1,585,000 all in Texas), China (1,261,000), Japan (725,000) and Taiwan (650,000).[4] The average list price for 2008 was $1600/tonne. Celanese is the largest producer (ca 25% of the worldwide capacity), while other significant producers include China Petrochemical Corporation (7%), Chang Chun Group (6%), and LyondellBasell (5%).[4]