【作者】 彭云；

【导师】 张兴元； 刘和文；

【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】 星形聚合物是一类具有特殊形态学结构的聚合物,因其自身表现出良好的反应性与多功能性,自出现以来一直受到广泛的关注。高分子科学家制备和研究了各种结构的星形聚合物,例如：多臂、杂臂、嵌段、接枝等。其中,具有层状结构的星形聚合物因其特殊的空间拓扑结构在药物传输／缓释放、医学成像、多层纳米膜的制备、分子捕捉和金属净化剂等领域展示出较大的应用前景。在前人研究工作的基础上,本论文主要是描述了几种结构新颖的层状结构星形聚合物的合成与性能研究,并对水相中制备聚苯酚进行了一定的研究,具体内容如下：1.用核交联的方法合成了大环聚苯乙烯封端的星形聚合物,类似的工作还未见报道。首先用“点击”化学和原子转移自由基聚合(ATRP)联用的方法合成了大环聚苯乙烯与线形聚苯乙烯的两嵌段蝌蚪状共聚物,接着用ATRP方法将蝌蚪状聚合物的活性链末端与二乙烯基苯交联形成核交联的星形聚合物。所得星形聚合物的臂的数量通过核磁谱计算得到,绝对分子量通过配有多角激光光散射检测器的凝胶液相色谱仪测量。用线形链较短的蝌蚪状前驱物制备的星形聚合物反而具有较大的分子量和更多的臂,这些聚合物环封端的星形聚合物拥有高度交联的核和很多扩散开来的臂,并有两个玻璃化转变温度,分别对应与线形和聚合物环。2.合成了一种结构新颖的四臂星形两嵌段共聚物(sPS-b-HPG)4,其中每条臂都是由线形的聚苯乙烯(PS)和超支化缩水甘油(HPG)组成的两嵌段共聚物。星形PS是以四官能团的引发剂用ATRP方法引发聚合而制备的,随后将其链末端转变为羟基,并以此星形PS的端羟基引发缩水甘油在三氟化硼乙醚(BF3-OEt2)催化下进行阳离子开环聚合。核磁共振氢谱和碳谱用来表征该嵌段共聚物的化学结构,DSC的分析结果表明(sPS-b-HPG)4有两个玻璃化转变温度,分别对应PS和HPG。在(sPS-b-HPG)4中掺杂的LiC1O4的量较少时,HPG的玻璃化转变温度会升高,而加入的LiC1O4的量较多时,HPG的玻璃化转变温度会降低,而LiC1O4的加入对PS嵌段的玻璃化转变温度基本没有影响。通过粘度分析方法研究了锂离子与(sPS-b-HPG)4以及与HPG之间的相互作用,发现sPS内核可以促进锂离子与HPG之间的相互作用。星形超支化层状结构固体电解质(sPS-b-HPG)4/LiClO4的离子电导率要明显高于单纯超支化HPG/LiCl04。3.水相分散的碳纳米管可以控制酶促氧化聚合苯酚的高分子结构,得到的聚苯酚中有90%的结构单元都是热稳定性很好的苯醚结构,聚合物的产率取决于碳纳米管的使用量,说明碳管的表面吸附对结构控制起到关键作用。在用碳纳米管为模板的酶催化苯酚聚合的基础上,以碳纳米管表面共价接枝的对苯二酚为起始剂,成功制备聚苯醚改性的纳米碳管。本工作为制备高性能的聚合物和碳纳米管的改性提供了一种新的途径。更多还原

【Abstract】 Star polymers, a kind of polymers with special morphological structures, have attracted great interests throughout the world due to its good performance in the responsiveness and versatility. A variety of star polymers with different structures, such as multi-arm, miktoarm, block, graft, and so on, have been prepared and studied. Due to their special topological structures, star polymers with a layered structure have exhibited good application prospects in the field of drug delivery/controlled release, medical imaging, multi-layer nano-membranes, molecular capturing and metal scavengers, etc. Based on the work of precursors, this dissertation mainly describes several interesting research in synthesis of star polymers with a layered structure and studied their performance thereby. In addition, we also do some research about enzymatic polymerization of phenol in water. The main results could be summarized as follows:1. We have synthesized macrocyclic polystyrene-(PS-) terminated star polymers via a core-crosslinking approach, and similar work has also not been reported. A tadpole-shaped macrocyclic PS-linear-PS copolymer was synthesized at first via both click reaction and ATRP polymerization method. The "living"ATRP chain-ends of the tadpole-shaped copolymers were linked together via ATRP polymerization with divinylbenzene to form a core-crosslinked star polymer. The number of arms attached to the macrocyclic star polymers was measured by using NMR, and absolute molecular weights by using gel permeation chromatography (GPC) with multiangle laser light scattering detector. The shorter tadpole-shaped precursors caused core-crosslinked star polymers with higher molecular weights and more arm numbers. These macrocyclic star polymers had a highly crosslinked core and many radiating arms. The macrocycle-terminated core-cross-linked star polymers showed two glass transition temperatures, one arising from the linear branches and another from the macrocycles.2. In this work, novel star-hyperbranched block copolymers containing four polystyrene arms and hyperbranched polyglycidol at the end of each arm (sPS-b-HPG)4 have been synthesized. The star polystyrenes were prepared through atom transfer radical polymerization of styrene starting from a four-arm initiator. The hydroxyl terminated PS star polymers served as precursors for the cationic ring opening polymerization of glycidol using BF3·OEt2 as the catalyst. The chemical structures of these block copolymers were characterized by using 1H and 13C NMR. DSC analysis indicated that the star-hyperbranched block copolymers exhibited two distinct glass transition temperatures corresponding to the linear PS and the HPG segments, respectively. The addition of LiClO4 increased the Tg of HPG segments at low concentrations, however, decreased the Tg at high concentrations. The Tg of PS segments was not affected by the addition of salts at all. Furthermore, the interaction of (sPS-b-HPG)4 with Li ions was studied by using viscosity analysis based on the Jones-Dole equation, and HPG was used as the control trial. The ionic conductivity of (sPS-b-HPG)4/LiClO4 electrolyte was measured to be higher than that of HPG/LiClO4 electrolyte at the same ratio of HPG/Li.3. Carbon nanotubes (CNTs) acted as a structural regulator for enzymatic polymerization of phenol in water. About 90% of total polymeric units in the obtained polymers are the highly thermally stable oxyphenylene units. The polymer-yields are dependent on the quantities of CNTs used. On the basis of MWNT-templated enzymatic polymerization of phenol, we grafted polyphenol chains to the surface of MWNT starting from the covalently anchored hydroquinone. This approach supplies a novel way for producing high performance polymers and for functionalization of the surface of CNT.更多还原