H/D isotope effect on miscibility of polyethylene glycols with benzene homologues

The systematic study of miscibility of polyethylene glycols (PEGs) of four average molecular weights equal to 200 a.m.u., 300 a.m.u., 400 a.m.u., and 600 a.m.u., with regular and deuterated benzene homologues has been presented. All systems show phase diagrams with upper critical solution temperatures (UCSTs). The miscibility of PEGs/benzene derivatives systems increases in the range: PEG/p-xylene > PEG/m-xylene > PEG/ethylbenzene > PEG/o-xylene > PEG/toluene. Deuterium substitution makes the miscibility of the investigated systems better and this finding is consistent with the Rabinovich concept. The miscibility isotope effects grow with the molar mass of polyethylene and the highest value has been obtained for toluene. The scaling equation and NRTL model have been used for describing the phase diagrams.