Soap-free poly（methyl methacrylate-ethyl acrylate-methacrylic acid） latex particles with narrow size distribution were synthesized by seeded emulsion polymerization, and the porous particles were created by a stepwi...Soap-free poly（methyl methacrylate-ethyl acrylate-methacrylic acid） latex particles with narrow size distribution were synthesized by seeded emulsion polymerization, and the porous particles were created by a stepwise alkali/acid treatment method. Effects of acid treatment conditions on the particle morphology were investigated. Results show that one to three pores were formed inside most of particles after post-treatment. At pH 7.0, when the treatment temperature was lower than 70℃, the size of particles and the volume of pores remained almost unchanged, and these two values increased significantly when the temperature was higher than 70℃. Both the particle size and the pore volume decreased with the increase of initial pH value and treatment time in the acid treatment. As the pH was below 4.0 and the treatment time was longer than 180 min, the particles shrunk in size.展开更多
Polymerization-induced self-assembly(PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast...Polymerization-induced self-assembly(PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast majority of emulsion PISA formulations using insoluble monomers leads to kinetically-trapped spheres. Herein, we present aqueous emulsion PISA formulations generating worms and vesicles besides spheres. Two monomers with different butyl groups, n-butyl(n BHMA) and tert-butyl(t BHMA) α-hydroxymethyl acrylate, and thus possessing different water solubilities were synthesized via Baylis-Hillman reaction. Photoinitiated aqueous emulsion polymerizations of n BHMA and t BHMA employing poly(ethylene glycol) macromolecular chain transfer agents(macro-CTAs, PEG45-CTA, and PEG113-CTA) at 40 °C were systematically investigated to evaluate the effect of monomer structure and solubility on the morphology of the generated block copolymer nano-objects. Higher order morphologies including worms and vesicles were readily accessed for t BHMA, which has a higher water solubility than that of n BHMA. This study proves that plasticization of the core-forming block by water plays a key role in enhancing chain mobility required for morphological transition in emulsion PISA.展开更多
The effect of oleates as emulsifiers on graft copolymerization of starch with acrylamide (AM) and acrylic acid (AA) in the inverse emulsion system is studied in this paper .The effect of the kinds of emulsifiers, the ...The effect of oleates as emulsifiers on graft copolymerization of starch with acrylamide (AM) and acrylic acid (AA) in the inverse emulsion system is studied in this paper .The effect of the kinds of emulsifiers, the proportion of mixed emulsifiers, the dosage of emulsifiers as well as the preparation methods of water-in-oil emulsion on monomer conversion, grafting ratio, and specific viscidity is discussed. The result indicates that calcium oleate or magnesium oleate as the emulsifier is better than sodium oleate or potassium oleate, and the mixture of oleic acid and its salt is better than any single compound.It is also concluded that monomer conversion reaches 99.7% and grafting ratio reaches 98.4% when m(oleic acid)/m(oleate sodium) is 60/40,m(starch)/m(monomers) is 1/1(among the monomers m(AM)/m(AA) is 4/1),v(oil phase)/v(water phase) is 1.2/1, initiator concentration is 2.4×10 -4mol·L -1,reaction temperature is 45～50℃,and reaction time is 6 hours.When mixed emulsifers concentration is 6%, the intrinsic viscidity reaches 1100ml·g -1.展开更多
基金The research was supported by the National 863 Project of China(No.2001AA242041).
文摘Soap-free poly（methyl methacrylate-ethyl acrylate-methacrylic acid） latex particles with narrow size distribution were synthesized by seeded emulsion polymerization, and the porous particles were created by a stepwise alkali/acid treatment method. Effects of acid treatment conditions on the particle morphology were investigated. Results show that one to three pores were formed inside most of particles after post-treatment. At pH 7.0, when the treatment temperature was lower than 70℃, the size of particles and the volume of pores remained almost unchanged, and these two values increased significantly when the temperature was higher than 70℃. Both the particle size and the pore volume decreased with the increase of initial pH value and treatment time in the acid treatment. As the pH was below 4.0 and the treatment time was longer than 180 min, the particles shrunk in size.
基金financially supported by the National Natural Science Foundation of China (No. 21674059)
文摘Polymerization-induced self-assembly(PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast majority of emulsion PISA formulations using insoluble monomers leads to kinetically-trapped spheres. Herein, we present aqueous emulsion PISA formulations generating worms and vesicles besides spheres. Two monomers with different butyl groups, n-butyl(n BHMA) and tert-butyl(t BHMA) α-hydroxymethyl acrylate, and thus possessing different water solubilities were synthesized via Baylis-Hillman reaction. Photoinitiated aqueous emulsion polymerizations of n BHMA and t BHMA employing poly(ethylene glycol) macromolecular chain transfer agents(macro-CTAs, PEG45-CTA, and PEG113-CTA) at 40 °C were systematically investigated to evaluate the effect of monomer structure and solubility on the morphology of the generated block copolymer nano-objects. Higher order morphologies including worms and vesicles were readily accessed for t BHMA, which has a higher water solubility than that of n BHMA. This study proves that plasticization of the core-forming block by water plays a key role in enhancing chain mobility required for morphological transition in emulsion PISA.
文摘The effect of oleates as emulsifiers on graft copolymerization of starch with acrylamide (AM) and acrylic acid (AA) in the inverse emulsion system is studied in this paper .The effect of the kinds of emulsifiers, the proportion of mixed emulsifiers, the dosage of emulsifiers as well as the preparation methods of water-in-oil emulsion on monomer conversion, grafting ratio, and specific viscidity is discussed. The result indicates that calcium oleate or magnesium oleate as the emulsifier is better than sodium oleate or potassium oleate, and the mixture of oleic acid and its salt is better than any single compound.It is also concluded that monomer conversion reaches 99.7% and grafting ratio reaches 98.4% when m(oleic acid)/m(oleate sodium) is 60/40,m(starch)/m(monomers) is 1/1(among the monomers m(AM)/m(AA) is 4/1),v(oil phase)/v(water phase) is 1.2/1, initiator concentration is 2.4×10 -4mol·L -1,reaction temperature is 45～50℃,and reaction time is 6 hours.When mixed emulsifers concentration is 6%, the intrinsic viscidity reaches 1100ml·g -1.
