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
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
Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. I...Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. It was revealed that with increasing PAA amount, the crystal polymorph of CaCO 3 particles varied gradually from pure calcite through a mixture of calcite and vaterite to pure vaterite, and the particle size decreased generally. It was proposed that in solid-state reaction, PAA induced the formation of vaterite and the phase transformation from vaterite to calcite was prevented completely due to the absence of H 2O, resulting in the formation of pure vaterite particles.展开更多
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Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. It was revealed that with increasing PAA amount, the crystal polymorph of CaCO 3 particles varied gradually from pure calcite through a mixture of calcite and vaterite to pure vaterite, and the particle size decreased generally. It was proposed that in solid-state reaction, PAA induced the formation of vaterite and the phase transformation from vaterite to calcite was prevented completely due to the absence of H 2O, resulting in the formation of pure vaterite particles.
