Phase transitions of nematic rubbers

¹ Laboratoire de Physique de la Matière Condensée, Collège de France 75231 Paris Cedex 05, France
² Department of Physics, Graduate School of Humanities and Sciences Ochanomizu University - 2-1-1, Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan

Received: 17 March 2003
Accepted: 2 May 2003

Abstract

Single-crystal nematic elastomers undergo a transition from a strongly ordered phase N to an “isotropic” phase I. We show that: a) samples produced under tension by the Finkelmann procedure are intrinsically anisotropic and should show a small (temperature-dependent) birefringence in the high-temperature I phase; b) for the transition via cooling there is a spinodal limit but for the transition via heating there is no soft mode at the standard spinodal temperature; c) the transition is reminiscent of a martensitic transformation: nucleation of the I phase should occur in the form of platelets, making a well-defined angle with the director.