We report the crystalline structure and phase behavior of a series of comb-like polymers (PPy-Cn), which were prepared via N-alkylation reactions between a pyrrole monomer and n-alkyl bromides (n = 18–26). Analysis by temperature-dependent X-ray diffraction and Fourier transform infrared spectroscopy (FTIR), as well as differential scanning calorimetry reveals that the crystal structure, thermal events and packing mode are affected by PPy backbones, which exhibit stronger rigidity than those of previously reported comb-like polymers. Remarkably, variable-temperature (VT)-FTIR proves the formation of orthorhombic phase at very low temperature, while VT-wide-angle X-ray diffraction only presents the hexagonal phase, illustrating that FTIR is a very sensitive tool for analyzing the micro-packing mode of molecular chains. The enhanced side-chain crystallizable carbon atoms indicate that PPy polymeric backbones play a negative role in the regular packing of nano-crystallites formed by alkyl groups.
我们报告了一系列梳状聚合物(PPy-Cn)的晶体结构和相行为,这些聚合物是通过
吡咯单体与正烷基
溴化物(n = 18-26)之间的N-烷基化反应制备的。通过温度依赖的X射线衍射和傅里叶变换红外光谱(FTIR)分析,以及差示扫描量热法的研究表明,PPy主链会影响晶体结构、热事件和堆积模式,其刚性比先前报道的梳状聚合物更强。值得注意的是,变温FTIR证明在极低温度下形成了正交相,而变温广角X射线衍射仅呈现六方相,说明FTIR是分析分子链微观堆积模式的非常灵敏的工具。增强的侧链可结晶碳原子表明,PPy聚合物主链在正烷基形成的纳米晶粒的规则堆积中起到了负面作用。