Pan Yuehang, Ouchi Makoto
Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.
Commun Chem. 2025 Aug 26;8(1):259. doi: 10.1038/s42004-025-01663-3.
The tacticity of vinyl polymers, i.e., the regularity of the side-chain stereochemistry, plays a crucial role in determining their physical properties. For example, the crystalline properties of isotactic polypropylene endow it with outstanding mechanical properties. In general, stereo-regulation during polymerization is greatly affected by even slight differences in the steric demand and/or position of the polar groups of the monomer side chains. In other words, no universal strategy to precisely control the tacticity for a given monomer with different pendant groups has been developed so far. Here, we provide a ground-breaking method for a library synthesis of highly isotactic polyacrylamides (99% meso dyad) with various pendant groups, including polar structures and di-substituted motifs. For that purpose, we designed an acrylamide monomer with a pendant that is sufficiently bulky to control the polymer tacticity that can be replaced by another pendant after polymerization. The transformable bulky monomer underwent iso-specific radical polymerization and subsequent aminolysis with a primary or secondary amine afforded a series of isotactic polyacrylamides derived from the added amine. Moreover, we clarified the isotacticity-dependent physical properties of the resulting polymers, such as their glass-transition temperature, crystalline properties, and solubility/thermo-responsibility in water, through a comparison with the corresponding atactic polyacrylamides.
乙烯基聚合物的立构规整性，即侧链立体化学的规整性，在决定其物理性质方面起着关键作用。例如，等规聚丙烯的结晶性能赋予其优异的机械性能。一般来说，聚合过程中的立体规整性会受到单体侧链极性基团的空间需求和/或位置上即使是微小差异的极大影响。换句话说，到目前为止，尚未开发出一种通用策略来精确控制具有不同侧基的给定单体的立构规整性。在此，我们提供了一种开创性的方法，用于库合成具有各种侧基（包括极性结构和二取代基序）的高度等规聚丙烯酰胺（间同二元组含量为99%）。为此，我们设计了一种带有足够大侧基的丙烯酰胺单体，该侧基能够控制聚合物的立构规整性，并且在聚合后可以被另一个侧基取代。这种可转化的大单体进行等规特异性自由基聚合，随后用伯胺或仲胺进行氨解，得到了一系列由添加的胺衍生而来的等规聚丙烯酰胺。此外，通过与相应的无规聚丙烯酰胺进行比较，我们阐明了所得聚合物的立构规整性相关的物理性质，如它们的玻璃化转变温度、结晶性能以及在水中的溶解性/热响应性。
