Precise Synthesis of High Generation Dendrimer-Like Star-Branched Polymers and Their Applications

树状星形支链聚合物的合成方法包括两个基本反应：(1)α功能化活性阴离子聚合物与溴化苄功能化聚合物的连接反应和(2)溴化苄的转化反应。这两个反应定量地进行了几次，形成了高代树状星形支化聚合物，直到第七代。所得聚合物（第7代）是一个真正巨大的大分子，分子量为200万，分子量分布很窄（Mw/Mn =1.02），由508个聚合物段和512个末端组成。高密度聚合物组成的四个分支在每个结也成功地合成了聚合物的第三代。由于空间位阻的存在，第四代聚合物的合成没有成功。其他功能聚合物段已成功地引入到树状星形支化聚合物的最外层。它们分别涉及聚（2-乙烯基吡啶）、聚（甲基丙烯酸叔丁酯）、聚（3-全氟丁基丙基甲基丙烯酸酯）和聚（2,3-二羟丙基甲基丙烯酸酯）。通过引入这些片段，可以使聚合物具有碱性、酸性、离子型、疏水、疏脂、水溶性等特性。此外，还成功地引入了具有液晶性、手性和热响应性的甲基丙烯酸酯聚合物。它们的功能聚合物已经详细地研究了这些功能。树枝状星形支化聚合物的形状已被SAXS测量，发现是椭球形而不是球形。实现了树枝状星形支化聚合物的原子力显微镜结构成像。首次清晰地观察到基于综合方法的结构和内部分支点。

Dendrimer-like star-branched polymers have been synthesized by developing a novel methodology which involves two basic reactions: (1) linking reaction of α-functionalized living anionic polymers with benzyl bromide-functionalized polymers and (2) transformation reaction to benzyl bromides. The two reactions proceeded quantitatively several times, resulting in the formation of high-generation dendrimer-like star-branched polymers up to seventh generation. The resulting polymer (7th generation) is a really huge macromolecule possessing two million in molecular weight and a narrow molecular weight distribution (Mw/Mn =1.02) and comprising 508 polymer segments with 512 termini. Highly dense polymers consisting of four branches at each junction have also succeeded in synthesizing the polymers up to the third generation. The attempt to synthesize the 4th generation polymer was not successful possibly due to the steric hindrance. Other functional polymer segments have been successfully introduced into the outermost layers of dendrimer-like star-branched polymers. They involve poly(2-vinylpyridine), poly(tert-butyl methacrylate), poly(3-perfluorobutylpropyl methacrylate), and poly(2,3-dihydroxypropyl methacrylate), respectively. By introducing such segments, basic, acidic, ionic, hydrophobic and lipophobic, water-soluble characters could be provided to the polymers. Furthermore, the introduction of methacrylate polymers having liquid crystalline, chirality, and thermoresponsive characters were also successful. Their functional polymers have been examined in detail with respect to such functionalities. The shapes of the dendrimer-like star-branched polymers have been measured by SAXS and found to be ellipsoidal shapes rather than spherical ones. AFM structural imaging of the dendrimer-like star-branched polymers has been realized. The structures based on synthetic methodology as well as internal branching points could be clearly observed for the first time.