2478-10-6Relevant articles and documents
Enzyme-induced formation of thermoreversible micellar gels from aqueous solutions of multiresponsive hydrophilic ABA triblock copolymers
Woodcock, Jeremiah W.,Jiang, Xueguang,Wright, Roger A. E.,Zhao, Bin
, p. 5764 - 5775 (2011)
We report on the synthesis of thermo- and enzyme-responsive hydrophilic ABA triblock copolymers, poly(ethoxydi(ethylene glycol) acrylate-co-4- ((dihydroxyphosphoryl)oxy)butyl acrylate)-b-poly(ethylene oxide)-b- poly(ethoxydi(ethylene glycol) acrylate-co-4-((dihydroxyphosphoryl)oxy)butyl acrylate) (P(DEGEA-co-OPBA)-b-PEO-b-P(DEGEA-co-OPBA)), and the enzyme-induced formation of thermoreversible micellar gels from their moderately concentrated aqueous solutions at 37 °C. PDEGEA is a thermosensitive water-soluble polymer with a lower critical solution temperature (LCST) at 9 °C in water. The block copolymers were prepared by atom transfer radical polymerization of DEGEA and 4-((di-tert-butoxyphosphoryl)oxy)butyl acrylate and subsequent removal of tert-butyl groups. To seek optimal conditions for enzymatic gelation of aqueous solutions of triblock copolymers, a study of dephosphorylation of a random copolymer P(DEGEA-co-OPBA) by acid phosphatase in water at 37 °C was carried out. The time for the solution to turn cloudy was found to decrease with the decrease of pH from 5.48 to 4.70 and level off from pH 4.39 to 4.23. The cleavage of phosphate groups made the polymer less hydrophilic and decreased the LCST from above to below 37 °C. Therefore, pH 4.4 was selected to conduct the enzyme-induced gelation of 7.9 wt % aqueous solutions of P(DEGEA-co-OPBA)-b-PEO-b-P(DEGEA-co-OPBA). The gelation processes were monitored by rheological measurements; the sol-gel transition temperature decreased and the gel strength increased with the increase of reaction time. The gels formed were thermoreversible; lowering temperature converted the gels to free-flowing liquids. From 1H and 31P NMR spectroscopy analysis, the degree of dephosphorylation was high. The formation of three-dimensional micellar network gels stemmed from the thermosensitive properties of the resultant dephosphorylated triblock copolymers, which was confirmed by a dynamic light scattering study. At a slightly higher pH (4.67), the enzyme-induced gelation was significantly slower, consistent with the observation of the effect of pH on dephosphorylation of the random copolymer by acid phosphatase.
Synthesis method of 4-hydroxy butyl acrylate
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Paragraph 0043; 0046; 0047; 0050; 0051; 0054, (2021/11/21)
The invention belongs to the field of synthesis process development of photocuring diluents, and particularly relates to a synthesis method of 4-hydroxy butyl acrylate. The synthesis method of the 4-hydroxy butyl acrylate provided by the invention comprises the following steps: carrying out dehydration condensation cyclization on 1, 4-butanediol and acrolein under the catalytic action of a strong acid catalyst to obtain 2-vinyl-1, 3-dioxoheptacyclic ring, and then carrying out oxidation ring opening on the 2-vinyl-1, 3-dioxoheptacyclic ring under the action of ozone to obtain the 4-hydroxy butyl acrylate. The synthesis method of 4-hydroxy butyl acrylate provided by the invention has the advantages that the method is simple and convenient, the efficiency is high, and the obtained 4-hydroxy butyl acrylate product is high in purity and hydroxyl value, so that popularization and application of the synthesis method of 4-hydroxy butyl acrylate are facilitated.
Oxidative Deprotection of p-Methoxybenzyl Ethers via Metal-Free Photoredox Catalysis
Ahn, Deok Kyun,Kang, Young Woo,Woo, Sang Kook
, p. 3612 - 3623 (2019/03/11)
An efficient and greener deprotection method for p-methoxybenzyl (PMB) ethers using a metal-free visible light photoredox catalyst and air and ammonium persulfate as the terminal oxidants is presented. Various functional groups and protecting groups were tolerated in the developed method to achieve good to excellent yields in short reaction times. Significantly, the developed method was compatible with PMB ethers derived from primary, secondary, and tertiary alcohols and a gram-scale reaction. Mechanistic studies support a proposed reaction mechanism that involves single electron oxidation of the PMB ether.