Probe dependency of segmental interaction parameters in copolymers by inverse gas chromatography

Abstract

Inverse gas chromatography (IGC) has been widely used to determine the Flory-Huggins parameter, v, between two polymers using a series of solutes as probes. Many studies showed that interaction parameters were probe dependent. In recent studies, it was proposed that the difference in interaction energy between functional groups of solutes and solvent mixtures could lead to an apparent solvent solubility parameter different from the volume average of the components. An equation was derived to relate the probe dependency to the deviation of the solubility parameter. By plotting / 2 / 3 RT(v 23 /V 2 ) vs. the solubility parameter of solutes, a straight line could be obtained with a slope proportional to the deviation of the solvent solubility parameter.The plot was shown to yield negative slopes for miscible polymer blends. When there was an unfavorable interaction between two solvents, an opposite situation would be observed. In this study, the method was tested in two copolymer systems, and the copolymers were considered as mixtures of two homopolymers. The plots showed straight lines with positive slopes when v 23 was positive. The technique was shown to apply to copolymer systems also.

A library of tunable agarose carbomer‐based hydrogels for tissue engineering applications: The role of cross‐linkers

“…According to the Flory‐Rehner description, as said, swelling data can be used to evaluate some important structural parameters of the hydrogel such as: (a) mean mesh size ζ (nm), (b) average molecular weight between two following crosslinks M c (g mol −1 ), (c) mean crosslinkage density ν (mol cm −3 ) 11, 16, 32. Using a simplified version of the Flory‐Rehner equation,10, 12, 16 the average molecular weight M C was evaluated as a function of the volumetric swelling ratio, Q V , as: in this equation, V p is the specific volume of dry polymer, V 1 the specific volume of the solvent (PBS), and χ the Flory interaction parameter between polymer and solvent obtained from literature 33–35 where ρ p is the density of the dry polymer, obtained by pycnometry, and ρ s that of the solvent.…”

“…in this equation, V p is the specific volume of dry polymer, V 1 the specific volume of the solvent (PBS), and v the Flory interaction parameter between polymer and solvent obtained from literature. [33][34][35] Q V was evaluated from the mass swelling ratio (Q M ) through the following equation:…”

Probe dependency of flory–huggins interaction parameters between solvents: Cases of hydrocarbons and isosteric derivatives

“…(3) in immiscible systems led to an apparent positive interaction parameters 20. However, in a more recent study, Huang21 showed that random copolymers with different ratio of two monomers can be treated as a mixture of two homopolymers and eq. (9) still applicable treated in the same way.…”

Inverse Gas Chromatography

“…In another study, J.-C. Huang [12] tested two copolymer systems of poly(vinyl acetate); poly(dimethylsiloxane) and the copolymers as mixtures of two homopolymers. When two components are thermodynamically unfavorable in terms of their miscibility, their interaction parameters will be positive; hence, for polymer mixtures a small but positive x 0 23 could indicate an immiscible system.…”