The Collapse of Free Polymer Chains in a Network

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Science  21 Apr 1995:
Vol. 268, Issue 5209, pp. 395-397
DOI: 10.1126/science.268.5209.395


The conformation of linear polymer chains trapped in a matrix of cross-linked polymer has been measured by neutron scattering. Three regimes were found depending on the length of the linear chain, Nl, with respect to the mesh size of the network, Nc. When Nc > Nl, the radius of gyration, Rg, of the linear chain is the same as that observed in the uncrosslinked melt. When Nc < Nl, Rg shrinks according to the scaling relation Rg–1Nc–1 that has been predicted for isolated polymer chains trapped in a field of random obstacles. When Nc << Nl the linear chains are observed to segregate.