Structure Control of Polymeric Materials using Magnetic Fields

在这个项目中，我们重点研究（1）磁排列机制，（2）利用磁场制造新材料，（3）磁排列新方法。Re（1），嵌段共聚物微相结构的磁排列进行了研究。研究发现，圆柱体和薄片结构在磁场下排列。检查了各种可能的机制，最终得出结论：形状各向异性很可能是磁对准的主要因素。聚丙烯在超临界二氧化碳下结晶时会发生磁取向。Re (2), 聚丙烯在磁场下用成核剂处理时形成良好取向的透明薄膜。此外，液晶嵌段共聚物表现出透明且取向良好的膜。这两个案例表明，目前的研究已经克服了磁取向薄膜中透明度和取向的权衡。Re（3），我们利用特殊的动态磁场成功地实现了双轴晶体的3维取向。使用调幅或调频磁场来实现悬浮在液体介质中的微晶的 3D 精确排列。这项新技术提供了一种用粉末制造伪单晶的创新方法。

In this project, we focused on (1) mechanism of magnetic alignment, (2) fabrication of new materials using magneticfield, (3) novel methods of magnetic alignment.Re (1), magnetic alignment of microphase structure of block copolymers was studied. It was found that a cylinder and lamella structures align under magnetic fields. Various possible mechanisms were examined to finally conclude that it is most possible that shape anisotropy is a main factor for the magnetic alignment. Polypropylene underwent magnetic alignment when it was crystallized under supercritical carbon dioxide.Re (2), Polypropylene formed a well-aligned transparent film when treated with nucleating agents under a magnetic field. Also, a liquid crystalline block copolymer exhibited a transparent and well-aligned film. These two cases indicate that the trade-off of transparency and alignment in magnetically aligned films has been overcome in the present research.Re (3), we have succeeded in the 3-dimensional alignment of biaxial crystals using a special dynamic magnetic field. Amplitude or frequency modulated magnetic field was used to achieve the 3-D precise alignment of crystallites suspended in a liquid medium. This novel technique provides an innovative method to fabricate a pseudo-single crystal from powder.