排序方式: 共有47条查询结果,搜索用时 31 毫秒
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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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《Analytical letters》2012,45(12):1910-1921
Multiblock partial least squares (MB-PLS) are applied for determination of corn and tobacco samples by using near-infrared diffuse reflection spectroscopy. In the model, the spectra are separated into several sub-blocks along the wavenumber, and different latent variable number was used for each sub-block. Compared with ordinary PLS, the importance and the contribution of each sub-block can be balanced by super-weights and the usage of different latent variable numbers. Therefore, the prediction obtained by the MB-PLS model is superior to that of the ordinary PLS, especially for the large data sets of tobacco samples with a large number of variables. 相似文献
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首先合成双端羟基的聚对二氧环己酮预聚物(PPDO)和双端羧基的聚乙二醇预聚物(PEG),然后以丁二酸酐/二环己基碳二亚胺(DCC)将PPDO与PEG偶联共聚,得到PPDO/PEG多嵌段共聚物.通过1H-NMR和GPC表征了聚合物的结构和分子量.采用差示扫描量热法(DSC)和热重分析(TGA)研究了共聚物的结晶性能和热稳定性.用透析法制备了共聚物纳米粒子,并用动态光散射(DLS)表征了共聚物纳米粒子的粒径及分散度,结果表明,随着共聚物亲水链段PEG含量的增加,其纳米粒子更易形成,粒子粒径随共聚物分子量增大而增大. 相似文献
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The integration of multiple data sources has emerged as a pivotal aspect to assess complex systems comprehensively. This new paradigm requires the ability to separate common and redundant from specific and complementary information during the joint analysis of several data blocks. However, inherent problems encountered when analysing single tables are amplified with the generation of multiblock datasets. Finding the relationships between data layers of increasing complexity constitutes therefore a challenging task. In the present work, an algorithm is proposed for the supervised analysis of multiblock data structures. It associates the advantages of interpretability from the orthogonal partial least squares (OPLS) framework and the ability of common component and specific weights analysis (CCSWA) to weight each data table individually in order to grasp its specificities and handle efficiently the different sources of Y-orthogonal variation. 相似文献
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采用熔融扩链法制备了高分子量的全生物基聚丁二酸丁二醇酯(PBS)-聚丁二酸异山梨醇酯嵌段共聚酯.GPC测试结果表明,该嵌段共聚酯在较高的异山梨醇(Is)含量时仍具有较高的分子量,其M_n介于3.5×10~4~7.0×10~4之间.采用TGA和DSC对嵌段共聚酯的热稳定性和结晶性能进行了研究,结果表明嵌段共聚酯保持了PBS优异的热稳定性和结晶性能,即使异山梨醇含量达60 mol%,其熔点较PBS仅下降2 K.采用DMA分析了嵌段共聚酯的玻璃化转变温度T_g,发现随着异山梨醇含量的增加,其T_g随之升高,当Is含量为60mol%时,嵌段共聚酯的T_g高达68℃,并且共聚酯的2个链段具有很好的相容性.力学性能测试结果表明,异山梨醇的引入可使PBS的力学性能得到明显地提高和调控,随着异山梨醇含量的增加,嵌段共聚酯的拉伸强度先增加后降低,断裂伸长率约是PBS的2倍,其中,当异山梨醇含量达60 mol%时,嵌段共聚酯的屈服强度由PBS的35.0 MPa增至43.0 MPa. 相似文献
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Dr. Guifu Si Dr. Chao Li Prof. Min Chen Prof. Changle Chen 《Angewandte Chemie (International ed. in English)》2023,62(49):e202311733
Due to a continued rise in the production and use of plastic products, their end-of-life pollution has become a pressing global issue. One of the biggest challenges in plastics recycling is the separation of different polymers. Multi-block copolymers (MBCPs) represent an efficient strategy for the upcycling of mixed plastics via induced compatibilization, but this approach is limited by difficulties associated with synthesis and structural modification. In this contribution, several synthetic strategies are explored to prepare MBCPs with tunable microstructures, which were then used as compatibilizer additives to upcycle mixtures of polyolefins with other plastics. A multi-block+ strategy based on a reactive telechelic block copolymer platform was introduced, which enabled block extension during the in situ melt blending of mixed plastics, leading to better compatibilizing properties as well as better 3D printing capability. This strategy was also applicable to more complex ternary plastic blends. The polymer multi-block strategy enabled by versatile MBCPs synthesis and the multi-block+ strategy enabled by in situ block extension show exciting opportunities for the upcycling of mixed plastics. 相似文献
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《Journal of Macromolecular Science: Physics》2013,52(5):669-684
The physical properties and a microphase-separated structure of multiblockcopolymers based on flexible segments of poly(1,4-oxytetramethylene)(PTMO) and rigid crystalline segments of poly(butylene terephthalate) (PBT) modified by ionic units were studied. Ionic copolymers were characterizedby limiting viscosity number, melt flow index, and tensile property measurements. The mechanical behavior of ionic poly(ether-block-sulfonated ester)(PESE) copolymers can be compared to that of conventional hard-soft thermoplasticelastomers. The phase structure was studied using differential scanningcalorimetry (DSC). Clearly, the DSC results show that the ionic unitsin the polyester segments have no significant influence on the microphaseseparation structure of PESE. A small reduction of the degree of crystallinitywith increasing content of ionic groups in the polyester rigid segments wasobserved. This results from the effect of ionic forces caused by incorporationof ionic units in the polyester segments. 相似文献
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