Cordoyiannis George, Kralj Samo, Nounesis George, Kutnjak Zdravko, Zumer Slobodan
National Centre for Scientific Research Demokritos, 153 10 Aghia Paraskevi, Greece.
Phys Rev E Stat Nonlin Soft Matter Phys. 2007 Feb;75(2 Pt 1):021702. doi: 10.1103/PhysRevE.75.021702. Epub 2007 Feb 6.
A detailed x-ray scattering and high-resolution ac calorimetric study has been carried out near the smectic-A to chiral smectic-C phase transition of liquid-crystal compounds 4-(2-methyl butyl) phenyl 4-n-octylbiphenyl-4-carboxylate (CE8) and p-( n-decyloxy) benzylidene-p-amino-(2-methylbutyl) cinnamate (DOBAMBC) confined in hydrophilic and hydrophobic aerosil nanoparticle networks. The character of the transition, which is mean field near a tricritical point in bulk, is changed dramatically with an increase of aerosil-induced disorder. X-ray measurements revealed pretransitional behavior and compression of the smectic layers, phenomena that are strongly pronounced in high aerosil concentrations. A theoretical model that takes into account the interplay of relevant mechanisms is proposed to explain the observed phenomena. The effect of chirality on the interaction of liquid crystals with aerosils is discussed.
在限制于亲水性和疏水性气凝胶纳米颗粒网络中的液晶化合物4-(2-甲基丁基)苯基4-正辛基联苯-4-羧酸酯(CE8)和对-(正癸氧基)亚苄基-对-氨基-(2-甲基丁基)肉桂酸酯(DOBAMBC)的近向列相A到手性近晶相C相变附近，开展了一项详细的X射线散射和高分辨率交流量热研究。在本体中，该相变在三临界点附近为平均场特征，但随着气凝胶诱导无序度的增加，其特征发生了显著变化。X射线测量揭示了近晶层的预过渡行为和压缩现象，这些现象在高气凝胶浓度下表现得尤为明显。提出了一个考虑相关机制相互作用的理论模型来解释所观察到的现象。讨论了手性对液晶与气凝胶相互作用的影响。
