Study of the dynamic structure of microphase separation by X-ray small angle scattering using the CCD type X-ray detector

在不同的振荡剪切条件下，嵌段共聚物的层状结构取向表现不同。例如，聚苯乙烯-聚异戊二烯二嵌段共聚物的层状结构在振荡剪切作用下，根据其频率、振幅和温度的不同，取向为垂直或平行或横向。取向行为还依赖于振荡剪切的时间过程。如果明确了这种行为的潜在机制，就可以对其进行调整，从而设计出新的机械性能。因此，研究纳米尺度结构（分子结构）与振荡剪切条件（频率、温度、应变）的关系具有重要意义。在这项研究中，我们开发了一种高灵敏度CCD x射线探测器，使我们能够以亚秒的时间分辨率记录时间分辨的小角度x射线散射模式。接下来，我们开发了一种剪切机，可以让x射线束以不同的三个正交方向通过，同时对聚合物样品进行振荡剪切。结合上述装置，利用同步辐射时间分辨小角x射线散射技术，成功地观察了聚苯乙烯和聚异戊二烯嵌段共聚物的片层结构在振荡剪切作用下的取向行为。

The orientation of lamellar structure in block copolymers behaves differently under oscillatory shear with different conditions. For example, the lamellar structure of polystyrene-polyisoprene di-block copolymer is orientated in either perpendicular or parallel or transverse under oscillatory shear, depending on its frequency and its amplitude and temperature. The orientation behavior is also dependent on time course of the oscillatory shear. If the underlying mechanism of this behavior is clarified, this behavior is tailored so that new mechanical properties can be designed. Therefore, it is important to investigate the relation of nano-scale structure (molecular structure) and oscillatory shear condition (frequency, temperature, strain ).In this study, we have developed a high-sensitivity CCD X-ray detector which enables us to record time-resolved small-angle X-ray scattering patterns with a sub-second time resolution. Next, we have developed a shearing machine which may let an X-ray beam pass through with different three orthogonal directions while applying oscillatory shear to polymer sample. With the above apparatus combined, we have successfully observed the orientation behavior of the lamellar structure in block copolymer of polystyrene and polyisoprene under oscillatory shear with time-resolved small angle X-ray scattering technique using synchrotron radiation.