Light-Induced Formation of Dynamic and Permanent Surface Topologies in Chiral-Nematic Polymer Networks
Light-Induced Formation of Dynamic and Permanent Surface Topologies in Chiral-Nematic Polymer Networks
复制标题
DOI：
10.1021/ma301628h
复制
发表时间：
2012-10-09
期刊：
影响因子：
5.5
通讯作者：
Broer, Dirk J.
中科院分区：
文献类型：
--
作者：
Liu, Danqing;Bastiaansen, Cees W. M.;Broer, Dirk J.
我们报告的程序和材料，使图案化的表面拓扑结构的光，无论是在一个动态的方式，曝光后的结构消失或这样的变形永久保持。该方法是基于光敏交联的液晶网络与手性-手性分子秩序。聚合物网络是由一个小浓度的共聚偶氮苯单体的光响应。在暴露于图案化的UV光时，网络中的分子有序参数通过偶氮苯的反式至顺式异构化而降低，从而导致密度降低和相应的局部体积增加。在正常条件下，聚合物网络表现出完全弹性，并且表面变形是快速和可逆的。为了诱导永久变形，聚合物网络需要通过链转移剂进行调节，以控制网络主链的动力学链长，并允许偶氮苯部分的平面外重新取向和相应的分子有序损失。
We report a procedure and a material to make patterned surface topologies by light, both in a dynamic way where the structures disappear after exposure or such that the deformations remain permanently. The method is based on a photosensitized cross-linked liquid crystal network with chiral-nematic molecular order. The polymer network is made photoresponsive by a small concentration of copolymerized azobenzene monomers. Upon exposure with patterned UV light, the molecular order parameter in the network is decreased by the trans-to-cis isomerization of the azobenzene, resulting in a density decrease and corresponding local volume increase. Under normal conditions, the polymer network behaves fully elastic and the surface deformation is fast and reversible. To induce permanent deformation, the polymer network needs to be adjusted by chain transfer agents to control the kinetic chain length of the network main chains and allow out of the plane reorientation of the azobenzene moieties and a corresponding loss of molecular order.