【作者】 匡敏；

【导师】 江明；

【作者基本信息】 复旦大学 ， 高分子化学与物理， 2004， 博士

【摘要】 纳米尺度的新材料因其独特的结构和性能逐渐成为材料科学的研究热点之一。获得纳米材料的方法有两种：固体物理学和电子学中，通过平板印刷和刻蚀的过程，能够直接获得纳米结构，这被称之为自上而下(top down)，但是由于涂层的强紫外吸收，这种方法不能获得200nm以下的尺寸；自下而上(bottom up)的方法通过单个分子的自组装形成具有功能单元的多层次的有序结构。正因为如此，自组装引起了物理学，化学以及材料科学多个领域的科学家的广泛关注。 在高分子领域中，不断有文献报导通过高分子自组装的方法获得新结构，新形态。在本体中，通过调节两嵌段聚合物不同组份的含量，嵌段聚合物由于微相分离会形成球状，柱状以及层状等多种形态。高分子在溶液中的自组装体称之为高分子胶束。与小分子表面活性剂在水中的行为类似，嵌段或接枝共聚物在选择性溶剂中会组装形成胶束结构。球形胶束是高分子胶束中最为常见的形态。但是近年来，Eisenberg等人利用长度不对称的嵌段共聚物在选择性溶剂水中获得了球状、囊泡、层状以及棒状等多种形态的胶束。 聚合物空心球由于具能够包覆大量的或大尺寸的客体分子从而在生物化学，合成与催化领域有了广泛的应用。高分子自组装制备空心球的方法有很多种。Wooley，G，Liu及Sakurai等人以聚合物胶束的壳交联为基础，通过进一步降解胶束的核制备聚合物空心球。 含刚性组分的刚性链—柔性链嵌段共聚物在选择性溶剂中也可以获得直接获得聚合物空心球。例如Jenekhe等人合成了刚性—柔性两嵌段共聚物PPQ-b-PS(聚苯基喹啉—b—聚苯乙烯)，在刚性段PPQ的选择性溶剂中会形成以PPQ为壳，以PS为核的胶束。并且胶束会因制备条件的不同而出现球状、棒状和囊泡等多种形态。由于刚性链的规整排列的趋势使得球状和棒状的胶束会出现空心结构。很多的研究工作表明，含刚性链体系的相分离由于刚性组分规整排列的趋势而呈现出很多有趣的形貌。另外刚性组分的引入使得体系的Flory-Huggins参数增大，从而较低分子量的刚性链—柔性链嵌段齐聚物也会表现出一定的相分离行为。 Jiang等在长期研究大分子络合物的基础上提出了制备核壳之间只有非共价键(氢键，静电作用)连接的高分子胶束，“非共价键胶束”(non-convalently connected micelles，NCCMs)。例如，P4VP(聚4—乙烯基吡啶)和CPS(端羧基聚苯乙烯)会山J:毗睫基与按基间的氢键作用在它们的共同溶剂中形成可溶性的大分子络合物，进」步在络合物溶液中滴加某1组分的选择性溶剂则会形成以不溶组分为核，可溶组分为壳的非共价键胶束。在此基础上，还能够进一步制备非共价键连接的聚合物空心球。例如，P4VP和PS(OH)(聚六氟羚内基和苯乙烯共聚物)在P4VP的选择性溶剂中通过氢键形成以P4vP为壳，PS(OH)为核的高分子胶束，进步交联胶束的壳，溶解胶束的核即可获得聚合物空心球。 上述提到的“非共价键胶束”中采用的都是柔性链体系，而且只能在选择性溶剂中获得。最近，jiang等在刚性链一柔性链自组装体系的研究中取得了一定的进展。当以具有刚性结构的Pl(端梭基聚酞业胺)取代CPS，CPB(端梭基聚丁二烯)等柔性链作为“接枝链”，对PVPy一Pl体系的自组装进行了系统的研究，结果表明该体系在它们的共同溶剂中会有空心球形成。这种获得聚合物空心球的方法与文献报导的方法相比较，更直接，更简单。 本论文的工作正是在文献报导的含刚性组分嵌段共聚物的自组装及NCCM、离聚物自组装等研究基础[开展，具体的内容可分为两部分: 在第一部分工作中我们主要研究了利用刚性链一柔性链的自组装制备聚合物空心球 其一，我们合成了主链结构不同的刚性的端浚基聚酸亚胺Pl并且研究了它们与柔性的P4VP，PZVP在它们的共同溶剂中氯仿的自组装。结果表明，它们在共同溶剂中即可形成聚合物空心球。证实了关于刚性链一柔性链的聚合物对在它们的共1司溶剂中可以自组装形成聚合物空心球是一个普遍存在的现象。对于这种有刚性链参与的自组装的机制有了更深入的理解。进一步的研究表明，组成聚合物的相对组成会影响其自组装体的结构。即，刚性链的减少即接枝密度降低会使形成的聚集体变大。另外，柔性链的结构变化也会对聚合物空心球的形成产生影响。空间位阻小的柔性链有利于形成小的聚集体。 第一，我们合成了可以光聚合的队E，它的两端各具有两个梭基，以此替代前面采用的PI作为刚性组份，研究了它与两种结构不同的柔性组份P4VP和PZVP在共同溶剂THF中的自组装行为。我们发现虽然作为质子受体的柔性链在结构_仁有差别，但是这两种聚合物对在它们的共同溶剂中都可以自组装形成尺寸-在几百纳米的聚合物空心球。而且，它们都表现了一个共同的趋势，就是随着体系中质子给体与质子受体比例的减少，形成的空心球尺寸变大。这是一个刚性链一柔性链自组装的普遍规律。另外，当刚性的队E作为质子给体时，形成的空心球尺寸只有PI作为质子给体时的一半不到，分布也更窄。这说明在形成聚集体时，队E中的双端梭基比Pl中的单端按基更容形成氢键，因此更容易形成紧密的结构。同时，我们还尝试更多还原

【Abstract】 As an efficient approach to nanoscale materials with well-defined structures, self-assembly has generated broad interest in chemistry and materials science. It has been extensively studied that block and graft copolymers self-assembled into micelles with well-defined structures. The obtained polymeric micelles could be in spheres, vesicles, worm-like cylinders and other novel structures. Recently, self-assembly of block copolymers consisting of rigid and flexible components received special interests in that inherent tendency of the rod block to form orientational order greatly affects the details of molecular packing. In fact, it was reported that self-assembly of rod-coil block copolymers resulted in some unprecedented morphologies both in solution and in the solid state.Among the targeting materials from self-assembly of polymers, hollow spheres on nanometer and submicrometer scales have attracted much attention owing to their potentials for serving as carriers of catalysts, enzymes and drugs etc. Wooley et al. and Liu et al. produced hollow spheres via self-assembly of block copolymers into core-shell micelles followed by crosslinking of the shell and degradation of the core. ’’Layer-by-layer (LBL)" technique using alternative depositions of oppositely charged species on various templates, and subsequent sacrificing the core can produces diverse hollow spheres. In addition, vesicles and particles used as templates for in-situ polymerization to produce hollow spheres have been reported. Rod-coil block copolymers were found to be able to form large-size hollow spheres directly in their selective solvent.Recently, research efforts of Jiang’s group have been devoted to developing a block-copolymer-free strategy to fabricate micelles based on homopolymer pairs. This novel approach results in "non-covalently connected micelles’’ (NCCM), in which only hydrogen bonds rather than chemical bonds exist between the shell and core. As a typical example, the NCCM composed of poly(4-vinyl pyridine) (PVPy) shell and hydroxyl-containing polystyrene (PS(OH)) core was realized in a selective solvent for PVPy due to hydrogen bonding between the hydroxyl groups and pyridine units. Furthermore, subsequent cross-linking of the PVPy shell and dissolution of the PS(OH) core moiety led to hollow spheres.When we used a rigid rod polyimide (PI) with carboxyl ends as a building block to fabricate NCCM with PVPy in their common solvent chloroform, it was unexpected that hollow spheres were obtained. Comparing with the existing procedures for producing micelles and hollow spheres, this process of using rod-coil homopolymer pairs in their common solvent seemed much simpler and more straightforward. As we demonstrated in the previous paper, this unusual phenomenon can be attributed to two main factors: the rigid character of PI and its ’grafting’ to the PVPy chains. The propensity to parallel packing of the rod blocks is believed to play an important role in such unusual assembly behavior.The content of this thesis could be divided into two parts.First, structural factors of the rigid and coil polymer pairs influencing their self-assembly in their common solvent were investigated. Several pyridine-unit-containing polymers with different structures, i.e. poly(4-vinyl pyridine) (P4VP), poly(2-vinyl pyridine) (P2VP) ,the copolymers of styrene and 4- vinyl pyridine (SVP) and PS-b-P2VP block copolymer were used. Its counterparts, the rigid proton-donating polymers, carboxyl-ended polyimide and poly(amic acid) ester were used. All the rigid-coil polymer pairs could self-assemble into hollow aggregates in submicrometer size. The results show a common trend that the hydrodynamic radius of the assembled hollow spheres decrease with increasing the ratio of the rigid proton-donating polymer to the flexible proton-accepting polymer. It was also found, at the same weight ratio, the size of hollowspheres obtained from PAE/P4VP(P2VP) is much smaller than that of PI/P4VP(P2VP), this may be attributed to the double ends in PAE. Comparing with the mono-更多还原