In this work, ethylene/1‐hexene copolymerization with a novel SiO2‐supported inorganic and organic hybrid chromium‐based catalyst was investigated. This catalyst was prepared using the residual surface hydroxyl groups in Phillips catalyst to support bis(triphenylsilyl) chromate (BC) in order to get the merits from two important chromium‐based catalysts namely inorganic Phillips and organic S‐2 catalysts. The influences of addition amount of 1‐hexene and BC were systematically investigated. With increasing 1‐hexene from 0 to 7 vol%, the activity of HCat‐2 catalyst showed a decreasing tendency. Its copolymer also showed the better short chain branches distribution through the temperature rising elution fractionation cross successive self‐nucleation and annealing characterization.
As a kind of stimuli-responsive materials,the disulfide-containing material has received a tremendous amount of interest.A novel functional disulfide-containing waterborne polyurethane(DS-WPU)nanoemulsion was prepared via a one-step in situ phase inverse emulsification technique and its reducing-responsive prope rty was investigated using dithiothreitol as the reductant.Results showed that the DS-WPU nanoemulsion had a uniform particle size in nanoscale and a good film-forming characteristic,and the DS-WPU latex film exhibited great responsiveness along with a self-assembled behavior in the reducing environment to form WPU emulsion again,including a long-to-short process of the polymer chains. 相似文献
The synthesis and structure of a giant 102‐silver‐atom nanocluster (NC) 1 is presented. X‐ray structural analysis reveals that 1 features a multi‐shelled metallic core of Ag6@Ag24@Ag60@Ag12. An octahedral Ag6 core is encaged by a truncated octahedral Ag24 shell. The Ag24 shell is composed of a hitherto unknown sodalite‐type silver orthophosphate cluster (SOC) {(Ag3PO4)8}, reminiscent of the Ag3PO4 photocatalyst. The SOC is capped by six interstitial sulfur atoms, giving a unique anionic cluster [Ag6@{(Ag3PO4)8}S6]6?, which functions as an intricate polyhedral template with abundant surface O and S atoms guiding the formation of a rare rhombicosidodecahedral Ag60 shell. An array of 6 linear Ag2 staples further surround this Ag60 shell. [Ag6@{(Ag3PO4)8}S6]6? is an unusual Ag‐based templating anion to induce the assembly of a SOC within silver NC. This finding provides molecular models for bulk Ag3PO4, and offers a fresh template strategy for the synthesis of silver NCs with high symmetry. 相似文献
Crosslinked x-P(St-MAA) seed latex was first prepared via soap-free emulsion copolymerization of styrene (St) and methyl methacrylic acid (MAA) with divinyl benzene as crosslinker and ammonium persulfate as initiator, and x-P(St-MAA)/x-P(St-NaSS) core/shell latex particles were then synthesized through a novel seeded emulsion copolymerization of St and sodium styrene sulphonate (NaSS) in the presence of water-soluble crosslinker N,N′-methylene bisacrylamide (BAA) using oil-soluble 2,2-azobis isobutyronitrile as initiator. TEM observation indicated that narrow dispersed core/shell latex particles were obtained, and element analysis showed that NaSS unit content in the whole particle and in the shell reached 22.8 wt% and 51.2 wt%, respectively. 相似文献