The effect of attractive interactions on the nematic order of V2O5 gels

被引:41
作者
Pelletier, O
Davidson, P
Bourgaux, C
Livage, J
机构
[1] Univ Paris Sud, URA 002 CNRS, Phys Solides Lab, F-91405 Orsay, France
[2] Univ Paris Sud, UMR 130 CNRS, Utilisat Rayonnement Electromagnet Lab, F-91405 Orsay, France
[3] Univ Paris 06, URA 1466 CNRS, Lab Chim Mat Condensee, F-75252 Paris, France
来源
EUROPHYSICS LETTERS | 1999年 / 48卷 / 01期
关键词
D O I
10.1209/epl/i1999-00113-x
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
Aqueous suspensions of V2O5 ribbons form a lyotropic nematic phase at volume fractions larger than 0.7%. We investigate the effect of adding a monovalent salt (NaCl) to this charge-stabilized system. Without any added salt, the nematic ordering can be described by the Onsager model based on a hard-core repulsive potential. Adding salt induces the gelation of these suspensions. Very unexpectedly, it also induces the stabilization of the nematic phase with respect to the isotropic one in a way opposite to the predictions of the Onsager model and to the usual behavior of typical hard-rod fluids. Larger salt concentrations eventually lead to flocculation. These observations indicate the increasing influence of attractive interactions which we argue are most probably van der Waals attractions.
引用
收藏
页码:53 / 59
页数:7
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