Mechanics of Homeotropically Ordered Smectic‐A Elastomers with Global Oblate Chain Conformation

Abstract

Smectic-A elastomers combine one-dimensional translational order of rod-like segments with the rubber elasticity of a polymer network. In recent years, detailed investigations were carried out on elastomers showing a global prolate chain conformation. In this communication, the first experiments on fluorinated SA elastomers exhibiting a global oblate chain conformation are presented, where the polymer chains are on average compressed along the layer normal of the lamellar phase structure. The mechanical anisotropy is studied by means of thermoelastic experiments and stress-strain measurements. For the first time, the layer compression modulus B of smectic elastomers is directly measured. B is significantly larger as compared to conventional low molar mass liquid crystals and decreases significantly with increasing local disorder introduced by the isotropic crosslinker.

Effect of co-monomers' relative concentration on self-assembling behaviour of side-chain liquid crystalline elastomers

“…Although most of these LSCEs exhibits a nematic (N) phase, stable over a wide temperature range, 1,15 several works have been devoted to the achiral orthogonal smectic A (SmA) 11,[16][17][18][19][20] and to the tilted smectic C, 21,22 but also to chiral smectic C* (SmC*) elastomers. 23,24 According to two-step crosslinking procedure, 14 nematic LSCE lms are characterized by a specic macroscopic alignment of the local nematic director, n, along the stretching direction of the lm (Scheme 1a).…”