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1.
基于嵌段共聚物在软受限条件下能够自组装形成很多有序结构,在催化、电子器件、光学传感等领域有广泛的应用价值,目前只对线性三嵌段共聚物在软受限下的自组装形貌做了分析,对星形三嵌段共聚物在软受限下的自组装行为还未有一个统一的定论.在这项研究中,应用模拟退火来研究ABC星形三嵌段共聚物在软受限下的自组装行为,嵌段与溶剂没有选择性下(中性壁),通过调整三个嵌段(fA、fB和fC)的体积分数来构建相图,我们的模拟预测了各种独特的自组装纳米结构,包括薄片+球形、圆柱状,穿孔层,薄片+圆柱体,核壳补丁.然后通过改变嵌段与溶剂的选择性预测了链长度比为1:x:1的共聚物粒子形貌.通过计算接触数、均方根末端距与平均链长的比值以及平均键长随x的变化,验证了形貌转变机制.  相似文献   

2.
运用扩展的自洽场和密度泛函理论(SCF/DFF),研究ABC蝌蚪形两亲高分子在稀溶剂中的自组装形态,其中蝌蚪形两亲高分子由线形嵌段共聚物链AB嫁接到球形纳米颗粒C上构成.与以往研究的线形ABC两亲高分子相比,蝌蚪形两亲高分子的自组装形态有着很大的不同.在粒子亲溶剂,嵌段共聚物疏溶剂时,各组分问弱分凝条件下,蝌蚪形两亲高分子自组装成胶球状形貌;在强分凝条件下,随着嵌段共聚物疏溶剂性的增强,两亲高分子的自组织态由胶球状转变成四角、三角状形貌,其中嵌段B主要分布在各角上.通过改变各组分间的相互作用,在嵌段A亲溶剂,嵌段B和粒子疏溶剂时,粒子呈平行棒状或小方块状分布在胶球中.  相似文献   

3.
采用自洽场的方法对A2B共聚物熔体作了类似星形共聚物的处理,研究了该共聚物的相分离并给出了相图.与两嵌段共聚物的相图相比较而言,在A2B的相图中,只发现了三个经典的有序相:球状相、六角蜂窝形柱状相以及层状相.从两嵌段线形共聚物到Y形共聚物这一链结构上的变化使相图也发生了相应的改变:各相的相边界发生了很大的偏移并且层状相出现的区域被大大的拓宽了.因此,可以通过改变链的结构来控制高分子自组装的微相结构,从而代替传统的改变高分子链中各组分的比例.  相似文献   

4.
采用Monte Carlo模拟方法研究了线性ABC三嵌段共聚物在B嵌段的选择性溶剂中的自组装行为。模拟结果表明,改变B嵌段的亲水性,体系可以自组装得到多种形貌各异的胶束。随着亲水性的减弱,胶束发生了从Janus球状多核胶束到多间隔胶束再到圆盘状多核胶束的转变。通过进一步分析胶束中聚合物的链构象等微观结构信息,我们发现随着亲水程度的减弱,聚合物链构象发生了从伸展状态到伸展、折叠状态并存,最终再到伸展状态的一系列转变。  相似文献   

5.
采用我们前期发展的测定多相高聚物中界面相厚度及相区尺寸的NMR新方法对两种不同嵌段结构的聚苯乙烯-聚丁二烯嵌段共聚物进行了研究,并与关于界面相厚度的高分子物理理论结果进行对比. 该NMR方法采用偶极滤波-自旋扩散技术分别测定非界面相的柔性区与界面相中质子的百分含量,然后根据界面相与柔性相的几何关系计算界面相厚度. 研究结果表明这两种嵌段共聚物具有几乎相同的界面相厚度,该结果与Helfand等人关于多相高聚物中界面相厚度的自洽场理论预言基本符合.  相似文献   

6.
嵌段共聚物受限于软孔内的自组装   总被引:1,自引:0,他引:1       下载免费PDF全文
李明  诸跃进 《物理学报》2008,57(12):7555-7564
利用自洽场方法研究两嵌段共聚物受限于接枝均聚物链(聚合物刷)圆孔中的自组装相形貌.研究表明,当圆孔内径一定时,嵌段比f和聚合物刷C的体积分数φC是调控嵌段共聚物相形貌的主要因素,聚合物刷的弹性熵也起着重要作用.当f=0.7时,在聚合物刷的浸润下,贴近刷表面处AB嵌段共聚物构成环层状结构,随着φC的减小这种结构会周而复始地出现.当f处于0. 关键词: 嵌段共聚物 圆孔受限 聚合物刷 自洽场  相似文献   

7.
以阳极多孔氧化铝膜为模板,制备了一系列一维结构材料及其阵列体系,材料的结构和阵列方式可调.主要包括两方面内容:通过功能单体的自由基聚合,制备了核壳结构的双重凝胶纳米纤维PDMA/PNH4AA及其阵列,控制氧化铝膜表面的润湿性,双重凝胶纳米纤维的核壳结构可以发生相反转,通过银离子与PNH4AA相的选择性复合,制备了柔性银纳米纤维或管;结合嵌段共聚物的自组装和无机物的溶胶/凝胶过程,制备了一维有序介孔二氧化硅及其阵列体系,改变嵌段共聚物的浓度,可以控制二氧化硅的介观结构.此材料易于进行异质复合,因而便于制备功能性一维复合材料及其阵列体系.  相似文献   

8.
13C及29Si核磁共振研究了苯乙烯(S)及二甲基硅氧烷(Si)嵌段共聚物中硅氧烷软段的固体及溶液谱的自旋-晶格弛豫时间T1。固态嵌段共聚物主链29Si及侧甲基13C的T1都与均聚物的T1相近,但在CdCl3溶液中各种嵌段共聚物的T1与均聚硅氧烷相差颇大。用偶极-偶极相互作用来解释高聚物的自旋-晶格弛豫。苯乙烯-二甲基硅氧烷嵌段共聚物具两相结构,所以嵌段共聚物中软段及硬段微区中链段的运动与在均聚物分子中链段的运动模式基本相同。而CdCl3对聚苯乙烯或聚硅氧烷都是良溶剂,软段硬段之间有相互影响。所以其链段运动与均聚物不同,从而导致链段运动的相关时间τc变短和T1的增长。  相似文献   

9.
樊娟娟  于秀玲  梁雪梅 《物理学报》2013,62(15):158105-158105
本文采用自洽场理论模拟了AB/CD嵌段共聚物共混体系的自组装. 改变组分B与D间的相互作用, 得到了不同空间尺度上的两种层状结构和只能在非对称组成情况才能得到的核壳结构. 结果表明, 这种多尺度结构的形成是因为BD间排斥作用的减弱或者吸引 作用的增强导致二者间相互融合程度的增加. 当BD间的相互融合程度与AB和CD间的相互融合程度相当时, 体系会发生宏观层状与微观层状结构间的转变. 此外, 本文还从能量角度揭示了体系发生这种结构转变的深层次原因. 关键词: 嵌段共聚物 共混 多尺度结构 自洽场  相似文献   

10.
用吡啶作为荧光探针研究了嵌段共聚物PluronicF108胶团形成以及牛血清白蛋白(BSA)对嵌段共聚物胶团形成的影响。研究表明,BSA阻碍嵌段共聚物的胶团形成,BSA与嵌段共聚物疏水链段的疏水相互作用是其阻碍嵌段共聚物胶团形成的主要原因。  相似文献   

11.
We propose a new and general method for discovering novel ordered phases of block copolymer melts. The method involves minimizing a free energy functional in an arbitrary unit cell with respect to the composition profile and the dimensions of the unit cell, without any prior assumption of the microphase symmetry. Varying the initial conditions allows to search for different stable and metastable structures. Application of this method to ABC star and linear triblock copolymers using an approximate free energy reveals new morphologies not yet observed in experiment.  相似文献   

12.
This outlook paper focuses on micelles formed by ABC triblock copolymers (triblock terpolymers) and related systems resulting from mixtures of diblock copolymers. Micelles with different internal structure such as micelles with a heterogeneous core and a homogeneous corona or micelles with a homogeneous core and a mixed corona are presented. More complex nanoobjects such as vesicles and Janus particles are also reviewed. Finally, potential applications of these objects are discussed.  相似文献   

13.
The spherical surface is spatially discretized with triangular lattices to numerically calculate the Laplace-Beltrami operator contained in the self-consistent field theory (SCFT) equations using a finite volume method. Based on this method we have developed a spherical alternating-direction implicit (ADI) scheme for the first time to help extend real-space implementation of SCFT in 2D flat space to the surface of the sphere. By using this method, we simulate the equilibrium microphase separation morphology of block copolymers including AB diblocks, ABC linear triblocks and ABC star triblock copolymers occurred on the spherical surface. In general, two classes of microphase separation morphologies such as striped patterns for compositionally symmetric block copolymers and spotted patterns for asymmetric compositions have been found. In contrast to microphase separation morphology in 2D flat space, the geometrical characteristics of a sphere has a large influence on the self-assembled morphology. For striped patterns, several of spiral-form and ring-form patterns are found by changing the ratio of the radius of a sphere to the averaging width of the stripes. The specific pattern such as the striped and spotted pattern with intrinsic dislocations or defects stems from formed periodic patterns due to microphase separation of block copolymers arranged on the curved surface.  相似文献   

14.
The statistical theory of microphase separation in the ternary ABC triblock copolymers is presented and the corresponding phase diagrams are built both for the linear and miktoarm copolymers. For this purpose the Leibler weak segregation theory in molten diblock copolymers is generalized to multi-component monodisperse block copolymers with due regard for the 2nd shell harmonics contributions defined in the paper. The Hildebrand approximation for the χ-parameters is used. The physical meaning of this and alternative choices for the χ-parameters is discussed. The symmetric AfB1-2fCf copolymers with the middle block non-selective with respect to the side ones are shown to undergo the continuous ODT not only into the lamellar phase but also, instead, into various non-conventional cubic phases (depending on the middle block composition it could be the simple cubic, face-centered cubic or non-centrosymmetric phase, which reveals the symmetry of I41 32 space group No. 214 first predicted to appear in molten block copolymers). For asymmetric linear ABC copolymers a region of compositions is found where the weakly segregated gyroid (double gyroid) phase exists between the planar hexagonal and lamellar or one of the non-conventional cubic phases up to the very critical point. In contrast, the miktoarm (star) ABC block copolymers with one of its arm non-selective with respect to the two others are shown to reveal a pronounced tendency towards strong segregation, which is preceded by increase of stability of the conventional BCC phase and a peculiar weakly segregated BCC phase (BCC3), where the dominant harmonics belong to the 3rd coordination sphere of the reciprocal lattice. The validity region of the developed theory is discussed and outlined in the composition triangles both for linear and miktoarm copolymers. We present also the list of the 2nd shell harmonics (SAXS reflections) allowed and prohibited in some of the non-conventional morphologies due to the weak segregation considerations and comparison of our results with the preceding SCFT treatment of the ABC copolymers by Matsen.  相似文献   

15.
Block copolymers are a class of soft matter that self-assemble to form ordered morphologies on the scale of nanometers, making them ideal materials for various applications. These applications directly depend on the shape and size of the self-assembled morphologies, and hence, a high degree of control over the self-assembly is desired. Grafting block copolymer chains onto a substrate to form copolymer brushes is a versatile method to fabricate functional surfaces. Such surfaces demonstrate a response to their environment, i.e., they change their surface topography in response to different external conditions. Furthermore, such surfaces may possess nanoscale patterns, which are important for some applications; however, such patterns may not form with spun-cast films under the same condition. In this review, we summarize the recent progress of the self-assembly of block copolymers grafted onto a flat substrate. We mainly concentrate on the self-assembled morphologies of end-grafted AB diblock copolymers, junction point-grafted AB diblock copolymers(i.e.,Y-shaped brushes), and end-grafted ABA triblock copolymers. Special emphasis is placed on theoretical and simulation progress.  相似文献   

16.
The different confinement shapes can induce the formation of various interesting and novel morphologies, which might inspire potential applications of materials. In this paper, we study the directed self-assembly of diblock copolymer confined in irregular geometries with a soft surface by using self-consistent field theory. Two types of confinement geometries are considered, namely, one is the concave pore with one groove and the other is the concave pore with two grooves. We obtain more novel and different structures which could not be produced in other two-dimensional(2D) confinements. Comparing these new structures with those obtained in regular square confinement, we find that the range of ordered lamellae is enlarged and the range of disordered structure is narrowed down under the concave pore confinement.We also compare the different structures obtained under the two types of confinement geometries, the results show that the effect of confinement would increase, which might induce the diblock copolymer to form novel structures. We construct the phase diagram as a function of the fraction of B block and the ratio of h/L of the groove. The simulation reveals that the wetting effect of brushes and the shape of confinement geometries play important roles in determining the morphologies of the system. Our results improve the applications in the directed self-assembly of diblock copolymer for fabricating the irregular structures.  相似文献   

17.
Pore size, wall thickness, and microporosity of polymer-templated mesoporous silica (PTMS) can be controlled by using different nonionic triblock copolymers as soft templates. The evolution of the pore structure of PTMS was studied by using nitrogen and argon adsorption at 77 K in addition to powder X-ray diffraction and transmission electron microscopy.  相似文献   

18.
We suggest that ABC triblock copolymers provide a convenient and effective route to emulsifying blends of A and C homopolymers into co-continuous morphologies over a wide range of compositions. Direct transitions between disordered tricontinuous phases (“ABC microemulsions”) and spatially-periodic tricontinuous phases (e.g. gyroid or double-diamond cubic phases) should be possible in appropriately formulated alloys. We envision a broad range of potential applications to thermoplastic and thermoset polymeric materials. Received: 4 June 1997 / Revised: 17 September 1997 / Accepted: 13 October 1997  相似文献   

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