Three-layer core/shell latex particles with various shell crosslinking level and shell thickness were prepared by multistep emulsion polymerization, and the hollow latex particles with different morphologies were then...Three-layer core/shell latex particles with various shell crosslinking level and shell thickness were prepared by multistep emulsion polymerization, and the hollow latex particles with different morphologies were then obtained after alkali post-treatment. Influences of divinyl benzene （DVB） content and the core/shell mass ratio on emulsion polymerization and particle morphology were investigated. Results showed that with the increase of DVB content, the percentage of total amount of --COOH on the particle surface and free in aqueous phase （PSFa） decreased, and the morphology of the post-treated particles underwent evolution from cracked, intact hollow to deficient swelling structure. Decreasing the core/shell mass ratio could not only make more carboxyl groups encapsulated by the shell, but also increase the shell resistance to the swelling of the core. The uniform hollow latex particles with intact morphology were obtained when the DVB content was 3.54 wt% and the core/shell mass ratio was 1/6.展开更多
In order to prepare hollow latex particles with optimum morphology based on osmotic swelling principle, three- layer core/shell latex particles with 40 wt% MAA in the core were first prepared via multistep seeded emul...In order to prepare hollow latex particles with optimum morphology based on osmotic swelling principle, three- layer core/shell latex particles with 40 wt% MAA in the core were first prepared via multistep seeded emulsion copolymerization, in which monomers were added by a semi-continuous process with monomer addition under two different forms： pure monomers＇ mixture （monomer addition）, and pre-emulsified monomers （pre-emulsion addition）. Then, the hollow latex particles with different morphologies were obtained after alkali post-treatment. Influences of the monomer feeding mode on the emulsion polymerization and the particle morphology were investigated. Results showed that the pre- emulsion addition could significantly improve the polymerization stability in each step, and greatly enhance the uniformity of shell encapsulation. The sizes of the core and core/shell latex particles obtained by the pre-emulsion addition were smaller and more uniform than those synthesized by the monomer addition, and the hollow latex particles with intact morphology were generated by alkali post-treating of the core/shell latexes prepared from the pre-emulsion addition. As the core size increased, the morphology of the post-treated particles underwent evolution from hollow to collapse. Moreover, the mechanism of the particle morphological evolution was proposed.展开更多
A facile method is reported to controllably fabricate one dimensional （1D） polymer nan,astructures via metallogel template polymerization. The metallogel was prepared through coordination interactions between silver...A facile method is reported to controllably fabricate one dimensional （1D） polymer nan,astructures via metallogel template polymerization. The metallogel was prepared through coordination interactions between silver ions and a ligand （L） bearing three pyridyl groups in tetrahydrofuran （THF）. The diameters of the metallogel nanofibers could be tuned by the gel concentration （GC）. Due to its high thermal stability and facility of removal, the metallogel was used as the template for radical polymerization of diacryolyl-2,6-diaminopyridine （DADAP） to form poly-diacryolyl-2,6-diaminopyridine （PDADAP） nanostructures. The gradually eroding of the templates by PDADAP provided us an effective way to fabricate various nanostructures of the polymer. We have demonstrated that different 1D nanostructures, including n^noribbons, nanotubes and nanowires, could be selectively fabricated by adjusting polymerization time, monomer concentration and GC. The rheological properties of the gel samples were tested by a rheometer. As prolonging the reaction time, more and more polymers were formed and the strength of the resulting polymer gels became higher and higher. The simple preparation process, easy controlled microstructures and adequate gel strength would make it a facile synthetic method for different 1D polymer nanosturctures.展开更多
文摘Three-layer core/shell latex particles with various shell crosslinking level and shell thickness were prepared by multistep emulsion polymerization, and the hollow latex particles with different morphologies were then obtained after alkali post-treatment. Influences of divinyl benzene （DVB） content and the core/shell mass ratio on emulsion polymerization and particle morphology were investigated. Results showed that with the increase of DVB content, the percentage of total amount of --COOH on the particle surface and free in aqueous phase （PSFa） decreased, and the morphology of the post-treated particles underwent evolution from cracked, intact hollow to deficient swelling structure. Decreasing the core/shell mass ratio could not only make more carboxyl groups encapsulated by the shell, but also increase the shell resistance to the swelling of the core. The uniform hollow latex particles with intact morphology were obtained when the DVB content was 3.54 wt% and the core/shell mass ratio was 1/6.
文摘In order to prepare hollow latex particles with optimum morphology based on osmotic swelling principle, three- layer core/shell latex particles with 40 wt% MAA in the core were first prepared via multistep seeded emulsion copolymerization, in which monomers were added by a semi-continuous process with monomer addition under two different forms： pure monomers＇ mixture （monomer addition）, and pre-emulsified monomers （pre-emulsion addition）. Then, the hollow latex particles with different morphologies were obtained after alkali post-treatment. Influences of the monomer feeding mode on the emulsion polymerization and the particle morphology were investigated. Results showed that the pre- emulsion addition could significantly improve the polymerization stability in each step, and greatly enhance the uniformity of shell encapsulation. The sizes of the core and core/shell latex particles obtained by the pre-emulsion addition were smaller and more uniform than those synthesized by the monomer addition, and the hollow latex particles with intact morphology were generated by alkali post-treating of the core/shell latexes prepared from the pre-emulsion addition. As the core size increased, the morphology of the post-treated particles underwent evolution from hollow to collapse. Moreover, the mechanism of the particle morphological evolution was proposed.
基金financially supported by the National Natural Science Foundation of China(Nos.20874055 and 21174079)Hi-tech Research and Development Program(863 plan) of China(No.2009AA062903)
文摘A facile method is reported to controllably fabricate one dimensional （1D） polymer nan,astructures via metallogel template polymerization. The metallogel was prepared through coordination interactions between silver ions and a ligand （L） bearing three pyridyl groups in tetrahydrofuran （THF）. The diameters of the metallogel nanofibers could be tuned by the gel concentration （GC）. Due to its high thermal stability and facility of removal, the metallogel was used as the template for radical polymerization of diacryolyl-2,6-diaminopyridine （DADAP） to form poly-diacryolyl-2,6-diaminopyridine （PDADAP） nanostructures. The gradually eroding of the templates by PDADAP provided us an effective way to fabricate various nanostructures of the polymer. We have demonstrated that different 1D nanostructures, including n^noribbons, nanotubes and nanowires, could be selectively fabricated by adjusting polymerization time, monomer concentration and GC. The rheological properties of the gel samples were tested by a rheometer. As prolonging the reaction time, more and more polymers were formed and the strength of the resulting polymer gels became higher and higher. The simple preparation process, easy controlled microstructures and adequate gel strength would make it a facile synthetic method for different 1D polymer nanosturctures.
