Thermodynamics and mechanical properties of random copolymer networks

Abstract

We analyze of the thermodynamic properties of random crosslinked polymer networks made of phantom chains with compositional disorder. We start our investigations from an extended Edwards Hamiltonian and end with the discussion of the free energy and mechanical properties. Using replica field theory we determine and solve the saddle point equations. The physically relevant ground state is invariant against translations in the real space, but it depends strongly on the coupling parameters for interactions, topology and compositional disorder of the network. We predict three different thermodynamic states for random copolymer networks. For two regimes the saddle point shows a rotational symmetry after elimination of translation effects. Here the network behaves similar to a homogeneous network. The third regime corresponds to a ground state with broken replica symmetry. Here, the behavior of the random copolymer network shows similarities to the thermodynamical properties of spin glasses. The network state is comparable diluted proteins.