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21.
The hybrid micelles of polystyrene-b-poly((N-isopropyl acrylamide)-co-(4-vinylbenzyl chloride)) block copolymer(PS-b-P(NIPAM-co-VBC)) with Prussian blue(PB) in the corona were prepared by reaction of pentacyano(4-(dimethylamino)-pyridine)ferrate(Fe-DMAP)-attached PS-b-P(NIPAM-co-VBC) with Fe Cl3. The formation of the PB framework inside the micelles was verified by UV-Vis, FTIR and TGA. The morphology of the hybrid micelles was studied by TEM and compared with that of the neat and Fe-DMAP-attached PS-b-P(NIPAM-co-VBC). It is found that attachment of Fe-DMAP may change the short rod-like micelles of the neat PS-b-P(NIPAM-co-VBC) into spherical ones and lead to a smaller micelle size. The morphology of the hybrid micelles may be altered or remain unchanged after formation of the PB framework, depending on the chain structure of PS-b-P(NIPAM-co-VBC) and starting concentration. The thermoresponsive behavior of different micelles was studied using DLS. It is observed that attachment of Fe-DMAP can improve the hydrophilicity of the P(NIPAM-co-VBC) block, leading to weaker hysteresis of the micelle size during the heating and cooling cycle. However, the crosslinked PB framework in the micellar corona may result in a more evident hysteresis phenomenon and blur the two-stepwise change of the micellar size with temperature. 相似文献
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用ESR方法对MgCl2负载的钛系Ziegier-Natta催化剂进行了研究,获得了分辩率较好的谱图,并结合前人的工作将信号的归属同钛原子在MgCl2上的负载情况对应起来.同时考察了内外给电子化合物对ESR谱图的影响,探讨了它们可能的作用机理. 相似文献
23.
Synthesis and characterization of Fe(II)-coordinated PS-b-P[NIPAM-co-(VBC-Fe-DMAP)] block copolymers
In this work,a new type of block polymers,polystyrene-b-poly[(N-isopropyl acrylamide)-co-(vinyl benzyl chloride)](PS-b-P(NIPAM-co-VBC)),was prepared via reversible addition fragmentation transfer polymerization,then pentacyano(4-(dimethylamino pyridine))ferrate(Fe-DMAP) was attached to VBC units through a quaternization process.The Fe(Ⅱ)-coordinated PS-b-P[NIPAM-co-(VBC-Fe-DMAP)]block copolymers were characterized by ~1H-NMR,FT-IR and TGA.The self-assembly behavior of the block copolymers was also investigated and the micelle morphology was characterized by TEM.It was found that the PS-b-P(NIPAM-co-VBC) block polymer and Fe-coordinated block copolymer could both form spherical micelles in DMF/MeOH mixed solvent. 相似文献
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采用球形高效负载Ziegler-Natta催化体系(TiCl4-MgCl2/AlR3/二苯基二甲氧基硅烷(DPDMS)合成等规聚苯乙烯(iPS),催化效率最高可达7.7×103
gPS/gTi·h.通过多个Schulz-Flory最可几分布对产物的分子量分布曲线拟合分峰来研究iPs的分子量及分子量分布的变化,AlEt3能使产物中低分子量部分含量增加,Al(i-Bu)3则倾向于形成高分子量的活性中心.体系中加入氢气不仅能显著提高催化效率,而且使iPS的分子量分布显著增宽. 相似文献
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研究了一系列具有不同链段长度和组成的聚4-乙烯基吡啶-聚苯乙烯-聚4-乙烯基吡啶多嵌段共聚物(P4VP-b-PS-b-P4VP)n在其选择性溶剂甲苯和pH<3的水中的胶束化过程,主要研究了多嵌段共聚物链段长度、溶液浓度和溶剂对其胶束形态的影响.透射电镜和原子力显微镜结果表明随着P4VP段链的相对增长,多嵌段共聚物在甲苯中的胶束形态由蠕虫链状向短棒状到球状胶束变化,而其在pH<3的水溶液中均形成球形胶束.由于特殊的链结构,聚合物的浓度对(P4VP-b-PS-b-P4VP)n多嵌段共聚物的胶束行为和胶束形态有着重要的影响.同时,(P4VP-b-PS-b-P4VP)n多嵌段共聚物分子量分布的多分散性对其在选择性溶剂中的胶束形态也有所影响. 相似文献
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