新型树形聚合物的合成及应用

发布时间：2018-06-06 05:33

本文选题：树形聚合物 + 拓扑结构　；参考：《中国科学技术大学》2016年硕士论文

【摘要】：树形聚合物凭借其独有的拓扑结构形式,使其拥有了独特的性质,这使其在许多领域有着潜在应用。树形聚合物重要的两个分支,树枝状聚合物和超支化聚合物受到了学者们广泛地关注和研究。由于聚合物的拓扑结构对聚合物的性质有着巨大的影响,寻找更多简易和高效的方法来合成不同拓扑结构的聚合物已经成为高分子化学中一个重要的课题。作为树枝状聚合物的一个衍生结构,树枝状-线性-树枝这样的哑铃状聚合物兼具了树枝状聚合物和线性段聚合物的性质,这种结构的聚合物在许多领域受到了广泛的关注。就目前的研究水平来说,树枝状-线性-树枝状的合成方法可以被分为三类：(1)偶合法,具有两个反应官能团的线性聚合物和具有一个反应官能团的树枝状聚合物反应；(2)大分子试剂法,两个树枝状聚合物通过一个小分子连接形成大分子引发剂或者大分子链转移剂,再将合成得到的产物用于活性聚合得到树枝状-线性-树枝状聚合物；(3)分散法,首先合成两个末端都有反应官能团的线性聚合物,再通过不断重复的反应合成树枝状-线性-树枝状聚合物。但现有的技术利用这三种方法都有非常多的缺陷。我们结合了RAFT聚合、三硫代碳酸酯氨解、巯基迈克加成反应等几种高效的反应合成了结构规整的树枝状-线性-树枝状PAMAM-PNIPAM-PAMAM。这种方法的发现,为高效便利地合成结构规整统一的树枝状-线性-树枝状聚合物提供了一种很好的参考。自然界中有许多在外界环境刺激下而发生组装或者解组装的天然聚合物,这类聚合物在维持生命体正常功能方面有着巨大的作用。尽管人工合成了许多刺激响应型聚合物,但很少有能兼具自交联和自降解功能。我们合成的2-((2-硝基苄基)硫代)乙醇为末端的含二硫键的超支化聚酰胺-胺兼具了这两种功能。基于之前的工作,我们选择单体,合成了同时拥有温敏性和pH响应性的超支化聚酰胺-胺。在温度升到其LCST以上或者pH调至9时,聚合物会发生聚集,再升温使聚合物内部发生二硫键交换反应使得聚合物互相交联形成稳定的纳米凝胶。通过紫外光照使聚合物末端降解产生巯基乙醇,而产生的巯基乙醇会进一步与骨架中的二硫键发生交换使得纳米凝胶降解。我们这种方法的提出和采用为更多响应性聚合物的合成和应用提供了一种思路。
[Abstract]:Dendritic polymers have unique properties due to their unique topological structure, which makes them have potential applications in many fields. Dendritic polymers and hyperbranched polymers are two important branches of dendritic polymers. Because the topological structure of polymers has a great influence on the properties of polymers, finding more simple and efficient methods to synthesize polymers with different topologies has become an important subject in polymer chemistry. As a derivative structure of dendritic polymers, dumbbell polymers such as dendritic linearly dendritic polymers have the properties of both dendritic polymers and linear segment polymers. At the present level of research, dendritic-linear-dendritic synthesis methods can be divided into three types: 1) couple method. A linear polymer with two reactive functional groups and a dendritic polymer with a reactive functional group react with a macromolecular reagent method in which two dendritic polymers are connected by a small molecule to form a macromolecular initiator or a macromolecular chain transfer agent. The synthesized products were then used in the active polymerization to obtain dendritic linearly dendritic polymer (T3) dispersion. Firstly, linear polymers with two ends with reactive functional groups were synthesized. Dendritic-linear-dendritic polymers were synthesized through repeated reactions. However, there are many defects in the existing techniques using these three methods. The dendritic linear dendritic PAMAM-PNIPAM-PAMAM with regular structure was synthesized by combining RAFT polymerization, aminolysis of trithiocarbonate and mercapto Michael addition reaction. The discovery of this method provides a good reference for the efficient and convenient synthesis of dendritic linearly dendritic polymers with uniform structure. There are many natural polymers which are assembled or unassembled under the stimulation of external environment in nature. These polymers play a great role in maintaining the normal function of life. Although many stimuli-responsive polymers have been synthesized, few of them have self-crosslinking and self-degradation functions. The hyperbranched polyamide-amines with disulfide bonds at the end of the ethanol synthesized by our method possess both of these functions. Based on our previous work, we selected monomers to synthesize hyperbranched polyamides with both temperature sensitivity and pH responsiveness. When the temperature is higher than its LCST or pH is adjusted to 9, the polymer aggregates, and the reheating results in a disulfide bond exchange reaction within the polymer. The polymer crosslinks with each other to form a stable nanogel. Mercaptoethanol was produced by UV irradiation, and the resulting mercaptoethanol was further exchanged with the disulfide bond in the skeleton to degrade the nano-gel. Our method provides a method for the synthesis and application of more responsive polymers.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O631

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