Effect of crosslink density on the properties of monolithic polymer matrices: Reversed-phase gas-chromatography study

Monolithic polymer matrices of different natures and different degrees of crosslinking have been synthesized in capillaries with an inner diameter of 100 μm. The properties of the monolithic matrices are characterized by reversed-phase gas chromatography. Solubility coefficient S, Flory-Huggins parameter gC₁₂^∞, and reduced Flory-Huggins parameter gC₁₂^∞ are evaluated. For all tested sorbates, the values of S depend on the degree of crosslinking of the polymer, which is characterized by parameter gC₁₂^∞. In the case of all monolithic polymer matrices under study, the logarithm of the solubility coefficient plotted as a function of the squared critical temperature of sorbate is described by a straight line, a circumstance that is likewise typical of linear polymers. Parameter D/d _f ², which characterizes the rate of diffusion of low-molecular-mass compounds in the monolithic matrix, is calculated. For both polar and nonpolar polymers, the dependence of D/d _f ² on the degree of crosslinking follows an extremum pattern.