Miscibility of binary mixtures of highly fluorinated double-chain glycerophosphocholines and 1,2-dipalmitoylphosphatidylcholine (DPPC).

The miscibility of highly fluorinated glycerophosphocholines with conventional ones and among themselves has been studied by DSC. The least fluorinated DF4C11PC of the series displays restricted miscibility with DPPC. The binary systems formed from the mixed-chain fluorocarbon/hydrocarbon [F8E11][C16]OPC and the homogenous fluorocarbon DF8C11OPC or hydrocarbon DPPC, respectively, exhibit increased miscibility in both the gel and fluid phases, although both systems are far from ideal. The two structurally very close DF4C11PC and DF6C11PC phosphatidylcholines, whose chains differ by two difluoromethylenes, display a non-ideal mixing behavior in the fluid phase and partial miscibility in the gel phase, which contrasts with the nearly ideal mixing behavior of DMPC and DPPC whose chain differ by two methylenes. These results indicate that chain-chain discrimination exists between fluorinated and fully hydrocarbon chains, and are consistent with selective lateral chain-chain interactions, which are more important between hydrocarbon chains than between a hydrocarbon and fluorocarbon chain, or between fluorocarbon chains. (C) 1997 Elsevier Science Ireland Ltd.