【作者】 万文明；

【导师】 潘才元；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2010， 博士

【摘要】 高分子材料被广泛地应用于现代社会的各个领域,包括：航天,军工,民用等方面。而高分子材料的性能与聚合物的结构以及聚集态形貌是密切相关的。研究聚合物的结构以及聚集态形貌与其性能的关系对设计和制备符合人们需求的高分子材料具有重要意义。因此,本论文就聚合物拓扑结构控制以及聚合物聚集体形貌控制两个方面开展工作,并取得了以下研究成果：1)通过链转移试剂存在下的原子转移自由基自缩合乙烯基聚合,成功地实现了超支化聚合物的定向、控制增长。相对于其它方法诸如逐步加料法等,这种方法简单易行,具有明显的优势,且从根本上解决了超支化聚合物不能控制增长的问题。通过这个方法,我们成功地合成了超支化—线形—超支化哑铃型聚合物。该方法也为超支化聚合物在表面改性的应用提供了一新的方法。2)对引发剂型单体聚合,发现了一种简单可行的控制产物的拓扑结构的方法。将链转移试剂引入到引发剂型单体的原子转移自由基自缩合乙烯基聚合反应体系中,当CuBr/RAFT比例小于1时,将得到线形聚合物,而当CuBr/RAFT试剂比例大于1时,得到超支化聚合物。此方法仅仅需要改变催化剂的含量即可对聚合物的拓扑结构进行控制。3)研究了PEG-Br引发4-乙烯基吡啶和交联剂N,N-甲叉双丙烯酰胺在乙醇／水混合溶剂(1：1体积比)中的原子转移自由基分散聚合。发现聚合过程可分为两个阶段：在一小时内,是均相聚合反应,聚合速度为1.21 mol·L-1·h-1；反应一小时后,聚合反应速度将急剧地降低到0.009 mol·L-1·h-1,这是因为随着聚合反应的进行,嵌段共聚物发生相分离,形成以PEO为壳、P4VP为核的胶束。利用PEG-b-(4VP-co-MBA)胶束中的P4VP链段和金属间的强络合作用,制备了聚合物胶束／金纳米离子的复合物,并发现增大金离子的含量会促进胶束间的聚集。4)发现了一种简单、可行的制备高分子纳米材料的方法。在RAFT分散聚合反应中,适当调节聚合条件和投料比例,可制备不同的纳米聚合物材料。形成过程存在两个相变过程：相分离形成球形胶束,球形胶束重新组织形成其他纳米结构材料。我们简称这两个相变过程为PISR。嵌段聚合物的溶液自组装的驱动力为溶度参数；而PISR过程的主要驱动力为嵌段聚合物的化学组成变化。该方法得到的高分子纳米材料浓度高达500 mg／mL,对于嵌段聚合物的溶液自组装,这个浓度是不可想象的。这种方法制备的高分子纳米材料非常稳定,在超过10个月以后仍然稳定；干燥后非常容易再分散。为高分子纳米材料的进一步实际应用打下了基础。5)发明了一种制备高分子蛋黄／壳纳米粒子的简单易行的方法。调节PISR聚合体系中的AIBN/RAFT试剂比例即可实现蛋黄／壳纳米粒子的制备。研究发现,在制备蛋黄／壳纳米粒子时,AIBN/RAFT试剂比例存在最优值。只有当AIBN／RAFT试剂比例等于1时,所得的蛋黄／壳纳米粒子最均匀。当AIBN/RAFT试剂比例等于1／10时,得到囊泡。当AIBN/RAFT试剂比例等于2／1时,得到多空穴的高分子微球。当AIBN/RAFT试剂比例进一步增加到4／1时,得到实心的高分子微球。更多还原

【Abstract】 Polymer materials have been applied extensively in many fields, including space technologies, military industry and so on. It is well known that the properties of polymer materials rely mainly on their chemical structures and morphologies of aggregates. So investigation on control of the chemical structures and morphologies of the aggregates is highly desired. And if the relationships of chemical structures, morphologies of the aggregates with properties of the polymer materials can be established, we will design and prepare the polymer materials with expected properties for special application based on their structures and morphologies.So this thesis focuses on two main projects, control of the chemical structures of polymers and morphologies of polymeric aggregates. And the main achievements are as follows:1) Control of hyperbranched chain growth on both ends of PEO has been achieved in the ATRP of inimer using macro RAFT agent. With this simple and feasible synthetic strategy, the hyperbranched-linear-hyperbranched triblock copolymers have been prepared successively. Principle of this synthetic strategy is interrupting propagation of the hyperbranched chain radicals by transformation active species of their chains onto the functional group of linear PEO, thus propagation of hyperbranched chains is restructed, and the propagation at the end of PEO increases relatively. This provides a convenient method for grafting hyperbranched polymers on the polymer chains or solid material surface.2) Control topological structure of polymers has been achieved simply by tuning feed molar ratio of CuBr to macro RAFt agent in SCVP of inimer. When the feed molar ratio of CuBr to RAFT sites is less than 1, with aid of CuBr/PMDETA, a few of inimer acted as initiator in the RAFT polymerization of inimer, and the linear triblock copolymers with one bromine in each inimer units were produced. For this ratio larger than 1, the initiating sites in PEO chains initiated the SCVP of inimer to form dumbbell polymers. Thus, the topologies of the triblock copolymer can be tuned from linear to dumbbell polymers just by variation of feed molar ratio of RAFT sites to CuBr.3) The atom transfer radical dispersion polymerization (ATRP) of 4-vinylpyridine (4VP) has been carried out in ethanol/H2O mixture. The system displayed two stages of polymerization; the first stage is the formation of diblock copolymer with the polymerization rate of 1.21 mol·L-1·h-1 before 1h polymerization, and the second is the main polymerization in micelles formed from the aggregation of the resultant block copolymers with the polymerization rate of 0.009 mol·L-1·h-1. The Au/polymer composite nanoparticles were successfully prepared by complexation of P4VP with HAuCl4 and following reduction with NaBH4.4) Polymeric nanomaterials with multiple morphologies have been prepared by one-pot RAFT dispersion polymerization. The results of LLS, TEM and FESEM show existence of two phase transitions, the phase separation and re-organization of the formed spherical micelles during the formation of various nanomaterials. The1H NMR and GPC traces evidenced that every transition is related to the growth of the second PS chains, so the phase sparation and the re-organization are induced by polymerization. By appropriately selecting concentration of the monomer and the feed ratio, the uniform nanorods and vesicles have been prepared. The preparation of polymeric nanomaterials can be performed in concentration as high as 0.5 g/mL, this makes the extensive investigations of application possible.5) A facile and feasible approach for preparation of polymeric yolk/shell nanomaterials has been developed via one-pot RAFT polymerization induced self-assembly and reorgnization. The different yolk/shell morphologies could be created and tuned just by varying the ratio of AIBN/P4VP. And the ratio of AIBN/P4VP= 1 is the best condition to prepare polymeric yolk/shell nanomaterials. This strategy is more versatile in comparison with the template methods, and showed great potential for preparation of such nanostructural materials at large scale.更多还原