Mkhonta S K, Elder K R, Huang Zhi-Feng, Grant Martin
Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201, USA and Department of Physics, University of Swaziland, Private Bag 4, Kwaluseni M201, Swaziland.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Oct;88(4):042602. doi: 10.1103/PhysRevE.88.042602. Epub 2013 Oct 10.
The interplay between liquid crystallinity and microphase separation in comblike liquid-crystalline diblock copolymers is examined via a Brazovskii-type phenomenological model using both analytical and numerical calculations. For symmetric diblock copolymers we determine a critical electric field that is required to tilt the orientation of the constituent liquid crystals of the polymer side chains in the microphase-separated lamellar state. Such electrically induced reorientation of the liquid-crystal molecules can lead to substantially large changes of lamellar periodicity. Our numerical results show that highly aligned polymer lamellar domains can self-assemble when the liquid-crystal ordering precedes microphase separation, and that weak electric fields can be used to direct the self-assembly process due to the dielectric anisotropy of the liquid-crystal side chains. We also find that phase separation of asymmetric diblock copolymers can coexist with a network of liquid-crystal nematic orientations, with domain morphology depending on the details of copolymer and liquid-crystal coupling.
通过一个Brazovskii型唯象模型，利用解析计算和数值计算，研究了梳状液晶二嵌段共聚物中液晶性与微相分离之间的相互作用。对于对称二嵌段共聚物，我们确定了一个临界电场，该电场是使处于微相分离层状状态的聚合物侧链中组成液晶的取向发生倾斜所必需的。这种液晶分子的电致重排可导致层状周期性的显著变化。我们的数值结果表明，当液晶有序化先于微相分离时，高度取向的聚合物层状畴可以自组装，并且由于液晶侧链的介电各向异性，弱电场可用于引导自组装过程。我们还发现，不对称二嵌段共聚物的相分离可以与液晶向列取向网络共存，畴形态取决于共聚物和液晶耦合的细节。
