A Study for the Mesomorphic State of Polyorganophosphazene in Terms of Time-sharing X-ray Diffraction

可结晶聚有机磷腈(POP)具有所谓的T(1)转变，在T(1)转变过程中，聚合物从其三维有序结晶状态转变为三维有序介晶结构(例如，增量相)。这一转变一般位于POP的玻璃化转变温度和真实熔点之间。在本研究中，用分时X射线衍射法对两种聚磷腈的三角洲相结晶过程进行了结构研究，并与POP的热性能进行了比较。结果表明：(1)在140ﾟC下加热的聚[双(4-乙基苯氧基)磷腈](PB(4E)PP)薄膜快速降温至75ﾟC时，聚合物的介晶态保持不结晶。(2)用300K/mm的快速冷却速度得到的Pb(4E)PP薄膜的热图没有显示出任何放热行为，这与上面观察到的结构特征是一致的。(3)用低温扫描电子显微镜研究了冻结的Pb(4E)PP的形态特征。(4)我们用类似的方法研究了聚(双(3，4-二甲基苯氧基)磷腈](PB(DM)PP)三角洲相的结晶行为。并通过将样品快速冷却到室温，成功地冻结了其介观状态。当样品温度再次升高到70ﾟC时，伴随着晶型的改变，发生了结晶。这些结果表明，在PB(DM)PP的结晶过程中，链折叠可能不起重要作用。更多的同步辐射X射线衍射工作，特别是需要跟踪两种聚合物结晶的全过程。这条线路的工作将在未来继续进行。

Crystallizable polyorganophosphazenes (POP) have so-called T(1) transitions at which the polymers change from their 3-D ordered crystalline state to the 3-D ordered mesomorphic structure ( e.g., the delta phase ). The transition is generally known to locate between the glass transition temperature and the true melting point of POP.In this research, structural studies for crystallization processes from the delta phases associated with two types of polyphosphazenes have been carried out by a time-sharing x-ray diffraction method, and the findings were compared with the thermal properties of those POP examined. The results obtained are summarized as follows :(1) When the poly[bis(4-ethylphenoxy)phosphazene] (PB(4E)PP) films heated at 140ﾟC were cooled down rapidly to an isothermal temperature of 75ﾟC, the mesomorphic states of the polymer remained without crystallization. This freezing of the meso state was confirmed by the x-ray experiments with PSPC.(2) The thermogram for the PB(4E)PP film obtained by a rapid cooling rate of 300 K/mm did not indicate any exothermic behavior, as agreed with the structural features above observed.(3) Morphological features of freezed PB(4E)PP were also investigated by use of a cryo SEM.(4) We examined the crystallization behavior of the delta phase of poly(bis(3,4-dimethylphenoxy)- phosphazene] (PB(dM)PP) in a similar manner using time-sharing x-ray diffraction and DSC, and succeeded in freezing its meso state by cooling the sample rapidly down to room temperature. When the sample temperature was raised again to 70ﾟC, crystallization occurred in a company with crystal modification. These findings indicate chain foldings probably did not play an important role in the crystallization process in PB(dM)PP.More x-ray diffraction works by synchrotron experiments, in paticular, will be required to follow the whole process of crystallization of both the polymers. The works along this line will be continued in future.