DOI: 10.1051/jp2:1992253
J. Phys. II France 2 (1992) 2081-2088

Brillouin scattering from cross-linked gels

Francesco Mallamace¹, Norberto Micali², Cirino Vasi², Rama Bansil³, Sinisa Pajevic³ and Francesco Sciortino<sup>3

1</sup>  Dipartimento di Fisica, Universita' di Messina, 98166 Villagio S. Agata, C.P. 55, Messina, Italy
²  Istituto Tecniche Spettroscopiche del C.N.R., 98166 Messina, Italy
³  Center for Polymer Studies and Department of Physics, Boston University, Boston, MA 02215, U.S.A.

(Received 12 August 1992, accepted in final form 12 October 1992)

Abstract
In this letter we report Brillouin scattering measurements on methyl-methacrylate (MMA) gels crosslinked with varying amounts of ethylene-dimethacrylate (EDMA). We find that the k dependence of the phase velocity changes on increasing the cross-link content. For higher concentrations of crosslink we observe maxima and minima in the k dependence of the phase velocity. We associate these minima and maxima with spatial inhomogeneities in the gel, with the formation of regions of low and high cross-link density, respectively. This micro-phase separation is frozen in by the presence of the already existing spanning network.

© Les Editions de Physique 1992