Gopinadhan Manesh, Choo Youngwoo, Osuji Chinedum O
Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06511, United States.
ACS Macro Lett. 2016 Mar 15;5(3):292-296. doi: 10.1021/acsmacrolett.5b00924. Epub 2016 Feb 18.
We elucidate the roles of the isotropic-nematic (I-N) and nematic-smectic A (N-SmA) transitions in the magnetic field directed self-assembly of a liquid crystalline block copolymer (BCP), using in situ X-ray scattering. Cooling into the nematic from the disordered melt yields poorly ordered and weakly aligned BCP microdomains. Continued cooling into the SmA, however, results in an abrupt increase in BCP orientational order with microdomain alignment tightly coupled to the translational order parameter of the smectic layers. These results underscore the significance of the N-SmA transition in generating highly aligned states under magnetic fields in these hierarchically ordered materials.
我们使用原位X射线散射，阐明了各向同性向列相（I-N）和向列相-近晶A相（N-SmA）转变在液晶嵌段共聚物（BCP）磁场定向自组装中的作用。从无序熔体冷却到向列相时，会产生有序性差且排列松散的BCP微区。然而，继续冷却到近晶A相，会导致BCP取向有序性突然增加，微区排列与近晶层的平移有序参数紧密耦合。这些结果强调了N-SmA转变在这些分级有序材料的磁场作用下产生高度排列状态中的重要性。
