title: Thermal patterning of a critical polymer blend.
abstract: Utilizing the Soret effect, we have employed a moderately focused laser beam (30 microm, 20 mW) to write spatial composition patterns into layers of the critical polymer blend poly(dimethyl siloxane)/poly(ethyl-methyl siloxane) (PDMS/PEMS, M(w)=16.4/22.8 kg/mol) both in the one- and in the two-phase region a few degrees above and below the critical temperature T(c)=37.7 degrees C. Because of the critical divergence of the Soret coefficient, moderate temperature gradients are sufficient to induce composition modulations of large amplitude. In the two-phase regime the spinodal demixing pattern can be locally manipulated in a controlled way. 2D simulations based on a modified Cahn-Hilliard equation are able to reproduce the essential spatial and temporal features observed in the experiments.
authors.affiliation: Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Voit
authors.forename: A
authors.initials: A
authors.lastname: Krekhov
authors.forename: W
authors.initials: W
authors.lastname: Enge
authors.forename: L
authors.initials: L
authors.lastname: Kramer
authors.forename: W
authors.initials: W
authors.lastname: Köhler