Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 9: SYMPOSIUM: Polymer networks and beyond: From molecular structure to materials and biological functions POSTER

CPP 9.19: Poster

Saturday, March 5, 2005, 16:45–18:45, Poster TU D

Glassy states and microphase separation in crosslinked homopolymer blends — •Christian Wald¹, Annette Zippelius¹ und Paul M. Goldbart² — ¹Institut für Theoretische Physik, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen — ²Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801-3080, U.S.A.

We address the physical properties of blends of distinct homopolymers, crosslinked beyond the gelation point, via a Landau approach involving a pair of coupled order-parameter fields: one describing vulcanisation, the other describing local phase separation. Thermal concentration fluctuations, present at the time of crosslinking, are “frozen in” into the gel network. The resulting glassy fluctuations are analysed at the Gaussian level in various regimes, determined by the relative values of certain physical length-scales. We also analyse the enhancement, due to crosslinking, of the stability of the blend with respect to demixing. Beyond the corresponding stability limit, complete phase separation is prevented by gelation and replaced by microphase separation, which occurs up to a length-scale set by the mesh size of the network, as a simple variational scheme reveals.