Thermodynamics of sorption in the binary liquid crystalline system composed of the poly(propyleneimine) dendrimer and p-n-pentyloxy-p'-cyanobyphenyl by inverse gas chromatography.

A binary system composed of the liquid crystalline poly(propyleneimine) dendrimer and nematic p-n-pentyloxy-p'-cyanobyphenyl has been studied by thermomicroscopy, scanning calorimetry, and inverse gas chromatography. In this system, there is the columnar phase being stable within broad ranges of temperature and component ratio. Dependences of the retention volumes of various solutes, namely, hydrocarbons, alcohols, and amines, on composition of the sorbents are revealed to exhibit the maximum. Thermodynamic functions of sorption of n-alkanes and n-alcohols on the binary sorbents composed of the said liquid crystals have been calculated specifically. Thermodynamic solute-sorbent compatibility characterized by the activity coefficients of the solutes is dependent on the sorbent composition; namely, it is controlled by counterbalancing of the enthalpy or entropy factors. The nonadditive mode of the solute-sorbent interaction is explained by arising of the microdomain nematic structure enclosed in the columnar structure of the dendrimer.