共查询到18条相似文献,搜索用时 78 毫秒
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梳型嵌段共聚物微观相分离的耗散粒子动力学模拟 总被引:3,自引:2,他引:1
利用耗散粒子动力学(Dissipative particle dynamics, DPD)模拟方法研究了二维梳型嵌段共聚物的微观相分离, 得到了相形貌与侧链长度及链段间相互作用的依赖关系, 进一步与线型和星型嵌段共聚物微观相分离进行了对比. 模拟结果揭示了本体中影响梳形嵌段共聚物微观相分离的主要因素, 包括嵌段共聚物的组成\, 拓扑结构以及不同粒子间的排斥力. 相似文献
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原子力显微镜与透射电镜对比研究嵌段共聚物微相分离形态 总被引:3,自引:0,他引:3
嵌段共聚物微观相分离形态结构由于其理论与应用中的重要性一直是人们研究的热点 [1] .本文研究的聚苯乙烯 -聚乙烯 /聚丁烯 -聚苯乙烯三嵌段共聚物 (SEBS)为聚苯乙烯 -聚丁二烯 -聚苯乙烯 (SBS)饱和加氢后的产物 .由于中间嵌段中的双键大多已加氢饱和 ,过去一直没有合适的染色剂进行染色 ,所以在 2 0世纪 80年代中期以前 ,SEBS形态结构未见文献报道 [1] .近年来 ,由于新型染色剂 Ru O4 的应用 ,使得用透射电镜 (TEM)观察其微相分离形态成为可能 . 随着对嵌段共聚物形态结构认识程度深入 ,人们迫切希望能有新的手段提供更加丰富的… 相似文献
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采用Monte Carlo方法结合退火方法研究掺杂非对称两嵌段共聚物薄膜的相分离情况.发现随着掺杂极性粒子浓度的增加,嵌段共聚物薄膜体系由层状相逐渐转化成层状和柱状共混相,最后变成分布均匀的柱状相.当掺杂浓度增加到一定程度时,形成了如六边形(6-fold)、七边形(7-fold)和五边形柱状(5-fold)的相结构;六边形柱状相结构的比例随着浓度增加而增加,七边形(7-fold)和五边形柱状(5-fold)相结构的比例随着浓度增加而减小.同时还讨论了两嵌段共聚物大小与掺杂浓度的关系. 相似文献
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采用两步溶液聚合方法合成了一系列聚二甲基硅氧烷(PDMS)-4,4′-二苯基甲烷二异氰酸酯(MDI)-聚乙二醇(PEG)多嵌段共聚物.利用轻敲模式原子力显微镜(AFM)观察了嵌段共聚物的表明形貌,研究了退火、共聚物组成以及PEG分子量和不同的官能团对涂层表面微相分离行为的影响,同时对微相分离行为的形成机理也作了相应的探讨.研究表明,该嵌段共聚物即使在PDMS含量大于50wt%时,涂层表面仍呈现出规整有序的纳米级相分离结构,其中疏水相和亲水相分别由PDMS链段和MDI-PEG组分构成. 相似文献
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嵌段共聚物通过微观相分离形成的各种有序结构在纳米印刷、药物输送、太阳能电池模板制备等领域有着广泛的应用.如何实现这些有序结构的有效调控是大家普遍关心的问题.近期的实验及理论研究表明嵌段长度的多分散性对嵌段共聚物的微观相行为有着不可忽视的影响.本文综述了近年来在AB型两嵌段及ABA型三嵌段共聚物的实验及理论研究中的一些主要进展,重点介绍了基于耗散粒子动力学的模拟研究进展.并对多分散性可能带来潜在重要影响的嵌段共聚物相关体系的未来发展方向进行了展望. 相似文献
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着重介绍嵌段共聚物/均聚物共混体系的微相分离,微胶束的形成,微区的形态结构以及形态的控制。 相似文献
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Jilin Zhang Xinhong Yu Ping Yang Juan Peng Chunxia Luo Weihuan Huang Yanchun Han 《Macromolecular rapid communications》2010,31(7):591-608
Today, high‐ordered micro‐ and nano‐patterned surfaces are widely used in many areas, such as in the preparation of super‐thin dielectric films, photonic crystals, antireflective films, super‐non‐wetting surfaces, bio‐compatible surfaces and microelectric devices. Considering the critical fabrication conditions and the irreducible high cost of the photolithography technique in patterning nano‐scale structures (<100 nm), the development of other micro‐ and nano‐patterning techniques that can be used to fabricate long‐range ordered features – especially nanoscale arrays – is a promising subject in surface science. In contrast to the traditional photolithography patterning technique, block copolymers can spontaneously phase separate into arrays of periodic patterns with length‐scales of 10–50 nm, which provides an efficient pathway to pattern nanoscale features. Today, preparing long‐range ordered arrays by block copolymer microphase separation is one of the most promising techniques for the fabrication of nanoscale arrays, not only being a simple process but also having a lower cost than traditional methods. In this feature article, we first summarize the many techniques developed to induce ordering in the microphase separation of the block copolymer thin films. Then, evolution, order–order transitions and reversible switching microdomains are considered, since they are very important in the ordered engineering of microphase separation of the block copolymer thin films. Finally, the outlook of this research area will be given.
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Microphase Separation of Star-diblock Copolymer Films: a Dissipative Particle Dynamics Simulation 下载免费PDF全文
The microphase-separating behaviors of two types of star-diblock copolymers (Ax)4(By)4 and (AxBy)4 in thin films are studied using the simulation technique of dissipative particle dynamics. A variety of ordered mesostructures have been observed and the simulated phase diagrams show obvious symmetries for the (Ax)4(By)4 films and asymmetries for the (AxBy)4 films, besides, it is easier for the (Ax)4(By)4 than for the (AxBy)4 to carry out microphase separation under the same conditions, which has been recognized in bulk and can be ascribed to the structural difference between the two types of star copolymers. There are some correspondences between the mesostructures formed in the film and those formed in bulk at the same composition fraction. Decreasing the thickness of film and strengthening the A-B repulsion both help the mesostructures enhance the degree of order. Composition fraction dependences of the mean-square radius of gyration in the two types of star copolymer films are almost contrary, which can be attributed to the differences in their respective structures.These findings can provide a guide to designing novel microstructures involving star-diblock copolymers via geometrical confinement. 相似文献
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剪切场作用下环形二嵌段共聚物微相形态变化的耗散粒子动力学研究 总被引:1,自引:0,他引:1
采用耗散粒子动力学(Dissipative particle dynamics, DPD)方法研究了在剪切场作用下, 环形二嵌段共聚物微观相分离过程中的形态变化. 在层状(lamellae, LAM)体系中发生了微相的平行重取向和平行-垂直转变以及剪切导致的波动不稳定现象. 对于穿孔层状(Perforated lamellae, PL)体系, 强剪切导致了穿孔层状-柱状(Hexagonal cylinder, HEX)微相转变. 在剪切场作用下, 柱状体系中同样也有平行重取向发生. 可以用相区破坏-相区重生的两步机理描述微相的平行重取向、平行-垂直转变以及PL-HEX转变现象. 在球状相(Body centered cubic, BCC)体系中发现了剪切诱导相融合. 相似文献
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采用自由基溶液聚合法成功合成了多面体低聚倍半硅氧烷(POSS)基杂化含氟丙烯酸酯共聚物,并采用核磁共振仪(NMR)和凝胶渗透色谱仪(GPC)表征了共聚物,其中POSS和含氟单体分步加入到反应中.首先将共聚物溶解到三氟三氯乙烷(F113)和乙酸乙酯的混合溶剂中配制成溶液,然后通过直接在玻璃片上滴落共聚物溶液制备了共聚物涂膜.采用扫描电子显微镜(SEM)、X-射线光电子能谱(XPS)、原子力显微镜(AFM)和接触角测量仪考察了F113和乙酸乙酯的配比对共聚物涂膜表面形貌、表面元素组成、表面粗糙度以及表面疏水性的影响.实验数据表明POSS在表面能够聚集成纳米颗粒并能极大增强涂膜表面粗糙度和疏水性.共聚物表面同时存在POSS聚集与有机相微相分离两类相分离行为,并形成了复合粗糙结构.虽然POSS和含氟段竞争迁移到表面,但是随着混合溶剂中F113的增多,涂膜表面含氟量越来越多,同时POSS在表面的聚集体越来越少,表面平均粗糙度越来越小,最终涂膜的疏水性越来越强,这说明F113有助于提升氟的趋表迁移能力,使涂膜表面含氟链段占据较多的表面空间,从而抑制了POSS在表面聚集分布.当使用纯F113作为溶剂时,共聚物涂膜的表面氟含量为45.25%,平均粗糙度为93.4 nm,此时静态水接触角最大为135.0?,表现出优异的疏水性. 相似文献
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The effect of pressure on the microphase separation of diblock copolymer melts was investigated by dynamic density functional theory based on equation of state. The results correspond well with experiment data. With the application of high pressure, all of the phase regions corresponding to the different ordered morphologies become narrower. However, the pressure dependence of the order‐disorder transition temperature (TODT) relies on the symmetry of the diblock copolymer. In the very non‐symmetrical case when f is small, TODT decreases with increasing pressure, while in the symmetrical case when f = 0.5, TODT increases with increasing pressure. For the latter case, the increase in the total bead number of the system at the ODT is found, which is in good accordance with the experimental phenomenon that there is an increase in volume accompanying with the transition from ordered to disordered state. In contrast to the temperature, the pressure does not influence the starting time and the duration of microphase separation.
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聚苯乙烯大单体与丙烯酸丁酯接枝共聚物的微观分相与表面性能研究 总被引:2,自引:0,他引:2
研究了以大单体技术合成的不同侧链长度的苯乙烯与丙烯酸丁酯的接枝共聚物的侧链长度对其微观分相与表面性能的影响,发现仅当聚苯乙烯侧链分子量大于5900时,才可能发生部分微观相分离,分离后对其表面性能影响不明显。临界表面张力rc虽有差异,但色散力部分ysD的计算值却较一致,与所用参照液无关。实验证实,接枝共聚物的表面几乎全被低表面能的聚丙烯酸丁酯骨架所复盖,呈现出明显的表面富集现象。 相似文献
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利用TDGL方法模拟嵌段共聚物链长和浓度对A/B/A-B三组分体系相形态演化的影响 总被引:1,自引:1,他引:0
从Flory-Huggins自由能出发,得到了适合TDGL模拟的自由能泛函.在自由能中保留了各序参量的耦合项,并且还保留了链长的信息.利用自由能中的链长的信息,模拟了不同嵌段共聚物链长以及不同浓度下体系的形态变化,在均聚物的链长和浓度确定的条件下,存在一个使体系的相区尺寸最小的最佳嵌段共聚物链长.同时,在嵌段共聚物和均聚物的链长都一定的情况下,研究了不同量的嵌段共聚物对体系相行为的影响,发现嵌段共聚物的浓度不同,体系的结构存在很大的区别.此外,如果均聚物A和B的浓度不同,其相区的结构也不同. 相似文献