嵌段共聚物的微相分离和形态

嵌段共聚物的微相分离行为和形态的研究是当前多相高聚物研究中众所瞩目的研究内容,无论从基础理论和应用实际都有其极为重要的意义,因此在这方面的研究已有不少报道,并日趋深入。 以最简单的嵌段共聚物A—B为例,如聚苯乙烯—聚异戊二烯二嵌段共聚物     

介观相分离对烯烃嵌段共聚物结晶动力学的影响

研究了介观相分离对烯烃嵌段共聚物(OBC)结晶动力学的影响.结果表明,OBC在保持介观相分离形态的情况下,结晶以三维生长的方式进行.原因可能是由于OBC的“相区溶合”造成的.OBC嵌段长度和嵌段数目存在一定的统计分布,其中某些较短的结晶性链段“溶解”于非晶区,这部分结晶性链段在结晶时起到了“传递”结晶的作用.     

聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物的微相分离与结晶

本工作研究了多分散和单分散聚氧化乙烯-聚苯乙烯-聚氧化乙烯三嵌段共聚物(PEO-PS-PEO)的结晶行为,及这些试样按非晶型嵌段共聚物进行微相分离后再结晶的结晶特点.     

PDMS-MDI-PEG多嵌段共聚物涂层表面微相分离行为研究

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.     

嵌段共聚物的微相分离及其质子交换膜性能

嵌段共聚物由于自身嵌段之间的热力学不相容性,容易发生微相分离而形成质子传导通道,并且采用可控活性聚合的方法可设计合成具有特定拓扑结构嵌段共聚物,使之成为最具潜力的一类质子交换膜材料。本文从用于质子交换膜的嵌段共聚物的微相分离热力学理论出发,分析了影响嵌段共聚物微相分离的各类因素,其中包括磺化度、共聚物拓扑结构、嵌段长度、嵌段序列分布、微观聚集结构以及表面形貌等,并对该领域未来的发展做了展望。     

高分子体系的自洽场理论方法及其应用

高分子体系的自洽场理论(self-consistent field theory, SCFT)是基于平均场近似的粗粒化模型, 特别适合研究发生相分离的非均相高分子体系在平衡态的相结构及相图, 其突出的优点在于能够考虑链拓扑构型、链序列分布等链的细节特点. 本文将对高分子体系的SCFT方法作较为详尽的介绍. 重点根据多年来我们自己的研究工作并结合实例, 简要介绍SCFT方法在具有复杂拓扑结构的多嵌段共聚高分子本体及稀溶液中的微相分离形态的预测、表面接枝高分子的纳米颗粒间的相互作用、含液晶体系的界面问题以及表面锚泊高分子链的囊泡形状问题等诸多前沿领域的具体应用. 最后, 展望了SCFT方法的可能发展方向和应用前景.     

嵌段共聚物／均聚物共混体系的微相分离和形态结构研究

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。     

用透射电镜法研究聚(苯乙烯-异戊二烯)二嵌段共聚物微相分离的微区尺寸

本文采用透射电镜(TEM)法,系统地研究了具有不同组成,不同分子量和不同形态结构的聚(苯乙烯-异戊二烯)二嵌段共聚物,并由TEM照片直接测量具有栓状,层状和有规双连续双金钢石(OBDD)结构的PS-PI二嵌共聚物的微区尺寸,讨论了其与分子量的关系。实验证明嵌段共聚物微相分离有规结构的微区尺寸大小与分子量呈2/3的关系。     

聚合物链长及表面吸附强度对三维受限下嵌段共聚物微观相分离的影响

利用动态密度泛函(Dynamic density functional theory, DDFT)方法研究了三维受限下嵌段共聚物的微观相分离, 讨论了共聚物链长和表面吸附强度对微观相形成与取向的影响. 体系中随机分布的等径微球提供三维限制结构, 体积分数为0.6. 增加微球的半径和体积分数, 能够使其从破坏微相规整结构的纳米掺杂过渡到提供三维限制结构. 调整嵌段共聚物与微球表面的相互作用对微相形成与取向有重要影响.     

Morphologies of Core-Shell-Cylinder-Forming ABC Star Triblock Copolymers in Nanopores

The self-assembly behavior of ABC star triblock copolymers can lead to a large number of nanostructures. Indeed, many new and interesting structures have already been discovered and proven to be hotspot in soft matter physics research. In this work, we introduce different phase diagrams of core-shell-cylinder-forming ABC star triblock copolymers under different conditions, including in-bulk and pore geometries with different sizes. The relation between the pore size geometries and their corresponding structures are also revealed. The different properties of the surface potential field that significantly affect the self-assembly process of ABC star triblock copolymers are investigated as well.     

The Effect of Pressure on the Microphase Separation of Diblock Copolymer Melts Studied by Dynamic Density Functional Theory Based on Equation of State

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 (T_ODT) relies on the symmetry of the diblock copolymer. In the very non‐symmetrical case when f is small, T_ODT decreases with increasing pressure, while in the symmetrical case when f = 0.5, T_ODT 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.

     

Synthesis and Self-assembly of a Linear Coil-Coil-Rod ABC Triblock Copolymer

An interesting order-order transition between two different complex nanostructures was observed in a new liquid crystalline linear coil-coil-rod ABC triblock copolymer（tri BCP）. First, the ABC tri BCP, poly（dimethylsiloxane）-bpolystyrene-b-poly{2,5-bis[（4-methoxyphenyl）oxycarbonyl]styrene}（PDMS-b-PS-b-PMPCS）, was synthesized through sequential atom transfer radical polymerization. The degrees of polymerization of PDMS, PS, and PMPCS blocks are 58, 159, and 106, and the corresponding volume fractions of PDMS, PS, and PMPCS are 0.09, 0.29, and 0.62, respectively. The phase behaviors of the PDMS-b-PS diblock copolymer precursor and the final triblock copolymer were studied by smallangle X-ray scattering, one-dimensional wide-angle X-ray scattering, and transmission electron microscopy experiments. The PDMS-b-PS precursor self-assembles into hexagonally packed cylinders with a relatively small periodic size after thermal annealing. When the triblock copolymer is annealed at a relatively low temperature（120 ○C） at which the PMPCS block is in the amorphous state, the tri BCP forms core-shell hexagonally packed cylinders（CSH） with a relativly large periodic size. After the tri BCP is annealed above 140 ○C at which the PMPCS block transforms to the liquid crystalline（LC） phase, the nanophase-separated structure transforms to a three-phase four-layer lamellar structure（LAM-3P4L）. Thus, accompanied with the transition of the PMPCS blocks from the amorphous state to the LC phase, the order-order transition from CSH to LAM-3P4 L occurs in the PDMS-b-PS-b-PMPCS ABC tri BCP.     

PEO-PPO嵌段共聚物反胶束的形成及其热力学行为

水增溶;临界胶束浓度;PEO-PPO嵌段共聚物反胶束的形成及其热力学行为     

Synthesis of Amphiphilic ABC Triblock Copolymers with PEO as the Middle Block

Summary: Stepwise anionic polymerization, catalytic hydrogenation, and atom transfer radical polymerization were performed to synthesize an amphiphilic ABC triblock copolymer, poly(ethylene‐alt‐propylene)‐block‐poly(ethylene oxide)‐block‐poly(hexyl methacrylate) (PEP‐b‐PEO‐b‐PHMA), with hydrophilic PEO as the middle block. The resulting block copolymers have well‐defined molecular weights and narrow molecular weight distributions as revealed by ¹H NMR spectroscopy and gel permeation chromatography.

GPC chromatograms of an ABC triblock copolymer, PEP‐b‐PEO‐b‐PHMA, and its intermediate precursors exhibiting narrow polydispersities.     

双亲三嵌段共聚物PEO-PPO-PEO在水溶液中相行为的理论研究

用自洽平均场理论的谱方法研究了双亲三嵌段共聚物PEO-PPO-PEO的分子量对其在水溶液相行为的影响. 理论预测了各种溶致液晶相的稳定区域. 通过系统地改变聚合物的分子量, 我们给出了各种PEO-PPO-PEO三嵌段共聚物在水溶液中的相图. 此外, 也研究了分子量对自组装结构各组分浓度分布的影响. 发现在给定的温度下, 聚合物的分子量是体系发生相分离的一个重要驱动力. 我们的理论结果与相关的实验很好地符合.     

Synthesis of Linear ABC Triblock Copolymers and Their Self‐Assembly in Solution

The self‐assembly of amphiphilic block copolymers has attracted the interest of a large number of research groups in the past two decades. Many examples have been reported using AB diblock copolymers, but the self‐assembly becomes more complex and shows a greater variety if ABC triblock copolymers are used. However, the synthesis of the polymer becomes more demanding since end‐group modifications or chain extensions become necessary. Using various kinds of polymerization techniques, pure triblock copolymers have been reported and their synthesis is covered in this review. Following the synthesis, a detailed and thorough analysis of the self‐assembly behaviour is the next step. We have selected promising and well characterized examples to show the range of self‐assembled structures possible, covering novel shapes of micelles but also polymersomes with an asymmetric membrane. Our selection of current examples in literature show the challenges and chances associated with amphiphilic ABC triblock copolymers.     

Studies on the Adsorption of Asymmetrical Triblock Copolymers by Scheutjens-Fleer Theory and Monte Carlo Simulation

The adsorption of asymmetrical triblock copolymers from a non-selective solvent on solid surface has been studied by using Scheutjens-Fleer mean-field theory and Monte Carlo simulation method on lattice model. The main aim of this paper is to provide detailed computer simulation data, taking A8-kB20Ak as a key example, to study the influence of the structure of copolymer on adsorption behavior and make a comparison between MC and SF results. The simulated results show that the size distribution of various configurations and density-profile are dependent on molecular structure and adsorption energy. The molecular structure will lead to diversity of adsorption behavior. This discrepancy between different structures would be enlarged for the surface coverage and adsorption amount with increasing of the adsorption energy. The surface coverage and the adsorption amount as well as the bound fraction will become larger as symmetry of the molecular structure becomes gradually worse. The adsorption layer becomes thicker with increasing of symmetry of the molecule when adsorption energy is smaller but it becomes thinner when adsorption energy is higher. It is shown that SF theory can reproduce the adsorption behavior of asymmetrical triblock copolymers. However, systematic discrepancy between the theory and simulation still exists.The approximations inherited in the mean-filed theory such as random mixing and the allowance of direct back folding may be responsible for those deviations.     

两亲性三嵌段共聚物PAA-PHB-PAA的合成及表征

本文用ATRP方法, 以两端溴化的聚β-羟基丁酸酯链段(Br-PHB-Br)作为大分子引发剂, 丙烯酸叔丁酯为单体, 合成了一种新的三嵌段共聚物聚丙烯酸叔丁酯-聚β-羟基丁酸酯-聚丙烯酸叔丁酯(PtBA-PHB-PtBA). 在酸性条件下进一步水解, 得到了一种两亲性的聚丙烯酸-聚β-羟基丁酸酯-聚丙烯酸(PAA-PHB-PAA)三嵌段共聚物.