Observations on the swelling of cross-linked poly(dimethylsiloxane) networks by solvents

The Flory Huggins Solvent parameter (χ) previously published for a range of solvents and a cross-linked silicone polymer, have been recalculated using the original swelling data, but including a term representing the loss of configurational entropy consequent on crosslinking. From the Shore hardness of the polymer, the Young’s modulus E was calculated. E = 6(C₁ + C₂), where C₁ and C₂ are the parameters from the Mooney Rivlin equation for the elastic deformation of an elastomer. Since C₁ is related to M_c, the average molecular weight between crosslinks, revised χ values could be calculated for various values of C₂/C₁. These showed that for good solvents for the silicone polymer, the values published previously were too high.