In this paper, the self-assembly of PS 43-b-PEO 45-b-PS 43 triblcok copolymer was investigated. The colloids were made by firstly dissolving the copolymer in the common solvents, including THF, 1,4-dioxane, and DMF, t...In this paper, the self-assembly of PS 43-b-PEO 45-b-PS 43 triblcok copolymer was investigated. The colloids were made by firstly dissolving the copolymer in the common solvents, including THF, 1,4-dioxane, and DMF, then droping water into the corresponding copolymer solution to induce the self-assembly. The aggregates prepared were characterized with TEM and AFM techniques. The experimental results demonstrated that the self-assembled vesicles were formed when THF and 1,4-dioxane were used as the common solvents to dissolve the copolymer, comparatively, using DMF as the common solvent resulted in the formation of spherical aggregates. The self-assembled aggregates observed, possessing hierarchical structures, could be used as either the nanostructures themselves for drug delivery systems, separations, catalysts, and so on, or templates or building blocks for more complex structures.展开更多
Polypropylene samples prepared with supported Ziegler-Natta catalysts were fractionated with temperature rising elution fractionation(TREF) technique and the tacticity distributions were obtained. It is found that the...Polypropylene samples prepared with supported Ziegler-Natta catalysts were fractionated with temperature rising elution fractionation(TREF) technique and the tacticity distributions were obtained. It is found that the polypropylene sample has a broad tacticity distribution when there exists no electron donor in the catalyst. the mutiple maximal wi(%)/At values indicates the presence of plural active sites in the catalysts. Experimental results show that both external and internal electron donors can narrow the tacticity distribution of PP.When external and internal electron donors are present in the catalysts, the obtained PP has the narrowest tacticity distribution.展开更多
文摘In this paper, the self-assembly of PS 43-b-PEO 45-b-PS 43 triblcok copolymer was investigated. The colloids were made by firstly dissolving the copolymer in the common solvents, including THF, 1,4-dioxane, and DMF, then droping water into the corresponding copolymer solution to induce the self-assembly. The aggregates prepared were characterized with TEM and AFM techniques. The experimental results demonstrated that the self-assembled vesicles were formed when THF and 1,4-dioxane were used as the common solvents to dissolve the copolymer, comparatively, using DMF as the common solvent resulted in the formation of spherical aggregates. The self-assembled aggregates observed, possessing hierarchical structures, could be used as either the nanostructures themselves for drug delivery systems, separations, catalysts, and so on, or templates or building blocks for more complex structures.
文摘Polypropylene samples prepared with supported Ziegler-Natta catalysts were fractionated with temperature rising elution fractionation(TREF) technique and the tacticity distributions were obtained. It is found that the polypropylene sample has a broad tacticity distribution when there exists no electron donor in the catalyst. the mutiple maximal wi(%)/At values indicates the presence of plural active sites in the catalysts. Experimental results show that both external and internal electron donors can narrow the tacticity distribution of PP.When external and internal electron donors are present in the catalysts, the obtained PP has the narrowest tacticity distribution.
