Solvent induced crystallization and phase transition is an interesting phenomenon that has been observed in many kinds of semicrystalline polymer. In the case of syndiotactic polystyrene (SPS) which exhibits complicated phase transition behavior, this process may be different when the phenyl rings are substituted by polarity groups. In our previous work, the crystal structures of a series of –OCH3 (OMe) substituted SPS and OMe-SPS/solvent complexes were analyzed (Macromolecules2021, 54, 1881 and Macromolecules2022, 55, 8222). In this particular work, the phase transition behavior of OMe-SPS, especially meta-OMe-SPS with different initial crystalline structures was discussed based on in situ 2-dimensional wide-angle X-ray diffractions (2D-WAXD) in the presence of organic solvent. It is found that meta-OMe-SPS in amorphous state and mesophase shows similar solvent induced phase transition like the cases of SPS. However Meanwhile, highly crystalline and oriented meta-OMe-SPS also exhibits organic solvent induced phase transition from β form with planar zigzag conformation into δ form with helical conformation, whichis has not been observed in SPS. The subsequent heating of meta-OMe-SPS δ and γ forms does not form β form, which is also unlike the situation of SPS δ/δe-γ-α/β transition. The OMe substituted group that changes the polarity of the phenyl rings may be the chemical structure region of affecting the chain conformation energy and phase transition behavior.

中文翻译：

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使用原位广角 X 射线衍射研究间规聚甲氧基苯乙烯的溶剂诱导结晶和相变


溶剂诱导结晶和相变是一种有趣的现象，在许多种类的半结晶聚合物中都观察到。对于表现出复杂相变行为的间规聚苯乙烯 （SPS） 来说，当苯环被极性基团取代时，这个过程可能会有所不同。在我们之前的工作中，分析了一系列 –OCH3 （OMe） 取代的 SPS 和 OMe-SPS/溶剂复合物的晶体结构 （Macromolecules2021， 54， 1881 和 Macromolecules2022， 55， 8222）。在这项特定的工作中，基于原位二维广角 X 射线衍射 （2D-WAXD） 在有机溶剂存在下，讨论了 OMe-SPS，尤其是具有不同初始晶体结构的 meta-OMe-SPS 的相变行为。研究发现，非晶态和中间相的 meta-OMe-SPS 表现出与 SPS 情况相似的溶剂诱导相变。然而，与此同时，高度结晶和取向的 meta-OMe-SPS 也表现出有机溶剂诱导的相变，从具有平面锯齿形构象的 β 形式转变为具有螺旋构象的δ形式，这在 SPS 中尚未观察到。随后的 meta-OMe-SPS δ 和 γ 形式的加热不会形成β形式，这也不同于 SPS δ/δe-γ-α/β 转变的情况。改变苯基环极性的 OMe 取代基团可能是影响链构象能和相变行为的化学结构区域。