Yusuf Yusril, Ono Yukitada, Sumisaki Yusuke, Cladis P E, Brand Helmut R, Finkelmann Heino, Kai Shoichi
Department of Applied Quantum Physics and Nuclear Engineering, Graduate School of Engineering, Kyushu University, Fukuoka 812-8185, Japan.
Phys Rev E Stat Nonlin Soft Matter Phys. 2004 Feb;69(2 Pt 1):021710. doi: 10.1103/PhysRevE.69.021710. Epub 2004 Feb 27.
We experimentally investigated the swelling behavior of thin films (approximately 150 microm) of liquid crystalline elastomers (LCEs) by low molecular weight liquid crystals (LMWLCs). The two LMWLCs used are the well-known nematic liquid crystals, 4-n-pentyl-4-cyanobiphenyl, and 4-methoxy-benzilidene-4-butyl-aniline. Both polydomain (POLY) and monodomain (MONO) LCE swelling are studied. In MONO LCEs (LSCEs), the director n empty set is uniformly oriented throughout the film. POLY films are made of many domains with different orientations. Its swelling behavior was similar to isotropic gels. In contrast, LSCEs revealed interesting results not anticipated by any theory. First, the LMWLC enters the LSCE by front propagation about three-times faster axially n empty set than radially n empty set. Second, only the LSCE dimensions radially n empty set expanded, while that axially n empty set did not change at all. Third, when the LMWLC director and the LSCE director are aligned (MONO2 samples), swelling takes place about twice as fast as when they are not aligned. Volume change dynamics of swollen L(S)CEs investigated as a function of temperature revealed several phase transitions by optical and calorimetry techniques.
我们通过低分子量液晶（LMWLCs）对液晶弹性体（LCEs）薄膜（约150微米）的溶胀行为进行了实验研究。所使用的两种LMWLCs是著名的向列型液晶，4-正戊基-4-氰基联苯和4-甲氧基-亚苄基-4-丁基苯胺。研究了多畴（POLY）和单畴（MONO）LCE的溶胀情况。在单畴LCE（LSCEs）中，指向矢n空集在整个薄膜中均匀取向。多畴薄膜由许多具有不同取向的畴组成。其溶胀行为类似于各向同性凝胶。相比之下，LSCEs显示出一些任何理论都未预料到的有趣结果。首先，LMWLC通过前沿传播进入LSCE，轴向n空集方向的速度比径向n空集方向快约三倍。其次，只有LSCE在径向n空集方向的尺寸膨胀，而轴向n空集方向的尺寸根本没有变化。第三，当LMWLC指向矢和LSCE指向矢对齐时（MONO2样品），溶胀速度是它们未对齐时的两倍左右。通过光学和量热技术研究了溶胀的L(S)CEs的体积变化动力学，揭示了几个相变。
