Determination of thermodynamic properties of macroporous glycidyl methacrylate-based copolymers by inverse gas chromatography

Abstract

Macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (PGME) was synthesized by suspension copolymerization and modified by ring-opening reaction of the pendant epoxy groups with ethylene diamine (EDA). Inverse gas chromatography (IGC) at infinite dilution was applied to determine the thermodynamic interactions of PGME and modified copolymer, PGME-en. The specific surface areas of the initial and modified copolymer samples were determined by the BET method, from low-temperature nitrogen adsorption isotherms. The specific retention volumes, Vg, of 10 organic compounds of different chemical nature and polarity (nonpolar, donor, or acceptor) were determined in the temperature range 333-413 K. The weight fraction activity coefficients of test sorbates, ohm(infinity)(1), and Flory-Huggins interaction parameters, chi(infinity)(12), were calculated and discussed in terms of interactions of sorbates with PGME and PGME-en. Also, the partial molar free energy, Delta G(1)(S), partial molar heat of mixing, Delta H-1(infinity), sorption molar free energy, Delta G(1)(S), sorption enthalpy Delta H-1(S), and sorption entropy, Delta S-S(1), were calculated. Glass transitions in PGME and PGME-en, determined from IGC data, were observed in the temperature range 373-393 K and 363-373 K, respectively.