The miscibility of poly(d,l-lactide-co-glycilide) with amphiphilic molecules at air/water interface

The miscibility of mixtures of poly(d,l-lactide-co-glycolide) (PLG) with two amphiphilic molecules was investigated when they were spread at air/water interface. The plateau in the π-A isotherms of the PLG mixture with cationic amphiphile, C12AzoC6PyBr, became short with gradually increasing the proportion of the amphiphile and the aggregates appeared in LB film became more uniform, both in scale and in shape, in comparing with the wormlike aggregation of pure PLG, by atomic force microscopy (AFM). However, the π-A isotherm of the PLG mixed with non-ionic amphiphile, C16AzoPy, showed no obvious changes corresponding to pure polymer except the molecular area increasing in some extent, and the domains with different heights on the LB film were clearly observed. Combing the results of UV-vis spectra, it is concluded that the PLG is basically miscible with C12AzoC6PyBr but is not with C16AzoPy, which is favorable to be a carrier for anionic biomolecules.