Surface segregation and miscibility in blends of poly(vinylidene fluoride-co-hexafluoro-acetone) with poly(butyl acrylate)

The surface segregation in poly(butyl acrylate) (PBA)/poly(vinylidene fluoride-co-hexafluoro-acetone) [P(VDF-HFA)] blends was confirmed by X-ray photoelectron spectroscopy (XPS), and is thought to be caused because the surface tension of P(VDF-HFA) is smaller than that of PBA. The PBA/P(VDF-HFA) blends were miscible at room temperature and exhibited a lower critical solution temperature (LCST) phase behavior. Thus, it was considered that the surface segregation of the P(VDF-HFA) component in PBA/P(VDF-HFA) blends was caused by the difference in surface tension between the components. Depth profiles [In(<Ø1 (d) -Øb 1) vs. depth (d), where Ø1 (d) and Øb 1 are the volume fractions at depth d from the surface and into the bulk, respectively] for PBA/P(VDF-HFA) blends were constructed by the mean-field treatment. The ln(Ø1(d) - Øb 1) vs. d plots for the PBA/P(VDF-HFA) blends could be approximated by a straight line.