Synthesis of an anionically chargeable, high-molar-mass, second-generation dendronized polymer and the observation of branching by scanning force microscopy
Synthesis of an anionically chargeable, high-molar-mass, second-generation dendronized polymer and the observation of branching by scanning force microscopy
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DOI：
10.1021/ja057964g
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发表时间：
2006-04-19
影响因子：
15
通讯作者：
Schlüter, AD
中科院分区：
文献类型：
--
作者：
Kasëmi, E;Zhuang, W;Schlüter, AD
描述了基于甲基丙烯酸酯的第二代 (G2) 树枝化大分子单体的有效合成及其自由基聚合成相应的高摩尔质量 G2 树枝化聚合物。通过凝胶渗透色谱 (GPC)、光散射和分析超速离心测定摩尔质量，并与云母上个性化聚合物链的扫描力显微镜 (SFM) 轮廓长度分析估计的值进行比较。该聚合物带有末端叔丁基保护的羧基，其用三氟乙酸的脱保护程度可通过核磁共振波谱法使用最高摩尔质量的样品来定量。固体基质上受保护（不带电）和未受保护（带电）树枝化聚合物的 SFM 成像显示，大部分是直链，但也有一些具有主链分支。研究了这些分支的性质并粗略估计了它们形成的程度。最后，描述了一个合成模型实验，该实验揭示了链转移（一种可能导致共价支化的过程）在本发明树枝化聚合物的合成中是否重要的方面。
An efficient synthesis of a methacrylate-based, second-generation (G2) dendronized macromonomer and its free radical polymerization to the corresponding high-molar-mass G2 dendronized polymer are described. The molar mass is determined by gel permeation chromatography (GPC), light-scattering, and analytical ultracentrifugation and compared with values estimated from a scanning force microscopy (SFM) contour lengths analysis of individualized polymer strands on mica. The polymer carries terminal tert-butyl-protected carboxyl groups, the degree of deprotection of which with trifluoroacetic acid is quantified by NMR spectroscopy using the highest molar mass sample. SFM imaging of both protected (noncharged) and unprotected (charged) dendronized polymers on solid substrates reveals mostly linear chains but also some with main-chain branches. The nature of these branches is investigated and the degree roughly estimated to which they are formed. Finally, a synthetic model experiment is described which sheds some light on the aspect of whether chain transfer, a process that could lead to covalent branching, is of importance in the synthesis of the present dendronized polymers.