Re. Baltus et al., SOLUBILITY AND DIFFUSIVITY OF CYCLIC OLIGOMERS IN POLY(DIMETHYLSILOXANE) USING CAPILLARY COLUMN INVERSE GAS-CHROMATOGRAPHY, Macromolecules, 26(21), 1993, pp. 5651-5656
The solubility and diffusivity of octamethylcyclotetrasiloxane (D4), d
ecamethylcyclopenta-siloxane (D5), and dodecamethylcyclohexasiloxane (
D6) oligomers in poly(dimethylsiloxane) (PDMS) have been measured usin
g inverse gas chromatography. Experiments were performed at 150, 175,
and 200-degrees-C. Solubility values were used to determine the Flory-
Huggins interaction parameter for each species. The interaction parame
ter values were found to range from -0.15 to 0.15 over the temperature
range of these measurements. Diffusion coefficient values were of ord
er 10(-6) cm2/s and were found to be in reasonable agreement with the
free volume theory of Vrentas and Duda.1,2 An empirical relationship b
etween diffusivity and solute molecular weight was developed at each t
emperature. Activation energies for diffusion were found to be 4.4 kca
l/mol for D4 and 7.1 kcal/mol for D5 and D6.