The crystallization of barium oxalate in the presence of a double-hydrophilic block copolymer poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) was investigated. Barium oxalate crystals with a complex fo...The crystallization of barium oxalate in the presence of a double-hydrophilic block copolymer poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) was investigated. Barium oxalate crystals with a complex form, such as fan-like aggregates consisting of rod-like BaC 2O 4·H 2O crystals and spherical aggregates consisting of flake-like BaC 2O 4·3.5H 2O crystals were readily produced in aqueous solutions of PEG-b-PMMA. This result may provide an effective method for controlling the morphology and polymorph of inorganic crystals.展开更多
The crystallization of calcite from mixed alcohol water solvents in the presence of a double hydrophilic block copolymer poly(ethylene glycol) block poly(methacrylic acid)(PEG b PMAA) has been investigated. It was rev...The crystallization of calcite from mixed alcohol water solvents in the presence of a double hydrophilic block copolymer poly(ethylene glycol) block poly(methacrylic acid)(PEG b PMAA) has been investigated. It was revealed that with increasing the volume fractions of ethanol or isopropanol, the morphology of the CaCO 3 particles generally varies from peanuts through rods to spheres in the presence of the polymer. Specifically, uniform rounded calcite rods, which are about 2 μm in length with an aspect ratio of 2.6, were obtained in the isopropanol solution with volume fraction 50%.展开更多
Ethyl α,α dibromoacetate was confirmed to be a difunctional initiator for the atom transfer radical polymerization of n butyl acrylate by means of gel penetration chromatography. When the polymerization of n butyl a...Ethyl α,α dibromoacetate was confirmed to be a difunctional initiator for the atom transfer radical polymerization of n butyl acrylate by means of gel penetration chromatography. When the polymerization of n butyl acrylate was carried out at different molar ratios of ethyl α,α dibromoacetate and ethyl α bromopropionate with CuBr/2,2′ bipyridine as the catalyst, polymers with bimodal molecular weight distributions were obtained, consisting of two narrowly distributed fractions, one of which was of a molecular weight double the other. Poly( n butyl acrylate) obtained with ethyl α,α dibromoacetate as the difunctional initiator was further used as the macroinitiator for styrene and methyl methacrylate in the presence of CuBr/2,2′ bipyridine respectively to prepare ABA triblock copolymers. It was found that high blocking efficiency was obtained for styrene. However, the polymer with bimodal molecular weight distribution was obtained for methyl methacrylate with a low molecular weight peak corresponding to that of poly( n butyl acrylate) macroinitiator. If the blocking polymerization was conducted with CuCl/ 2,2′ bipyridine as the catalyst to replace CuBr/2,2′ bipyridine, a high blocking efficiency was also obtained. [WT5HZ]展开更多
文摘The crystallization of barium oxalate in the presence of a double-hydrophilic block copolymer poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) was investigated. Barium oxalate crystals with a complex form, such as fan-like aggregates consisting of rod-like BaC 2O 4·H 2O crystals and spherical aggregates consisting of flake-like BaC 2O 4·3.5H 2O crystals were readily produced in aqueous solutions of PEG-b-PMMA. This result may provide an effective method for controlling the morphology and polymorph of inorganic crystals.
文摘The crystallization of calcite from mixed alcohol water solvents in the presence of a double hydrophilic block copolymer poly(ethylene glycol) block poly(methacrylic acid)(PEG b PMAA) has been investigated. It was revealed that with increasing the volume fractions of ethanol or isopropanol, the morphology of the CaCO 3 particles generally varies from peanuts through rods to spheres in the presence of the polymer. Specifically, uniform rounded calcite rods, which are about 2 μm in length with an aspect ratio of 2.6, were obtained in the isopropanol solution with volume fraction 50%.
文摘Ethyl α,α dibromoacetate was confirmed to be a difunctional initiator for the atom transfer radical polymerization of n butyl acrylate by means of gel penetration chromatography. When the polymerization of n butyl acrylate was carried out at different molar ratios of ethyl α,α dibromoacetate and ethyl α bromopropionate with CuBr/2,2′ bipyridine as the catalyst, polymers with bimodal molecular weight distributions were obtained, consisting of two narrowly distributed fractions, one of which was of a molecular weight double the other. Poly( n butyl acrylate) obtained with ethyl α,α dibromoacetate as the difunctional initiator was further used as the macroinitiator for styrene and methyl methacrylate in the presence of CuBr/2,2′ bipyridine respectively to prepare ABA triblock copolymers. It was found that high blocking efficiency was obtained for styrene. However, the polymer with bimodal molecular weight distribution was obtained for methyl methacrylate with a low molecular weight peak corresponding to that of poly( n butyl acrylate) macroinitiator. If the blocking polymerization was conducted with CuCl/ 2,2′ bipyridine as the catalyst to replace CuBr/2,2′ bipyridine, a high blocking efficiency was also obtained. [WT5HZ]
