Poly(diallyldimethyl ammonium chloride) (PDDA) and ferroelectric poly(vinylidene fluoride) (PVDF) composite ultrathin films on quartz glass prepared by electrostatic layer-by-layer self-assembly (SA) have been investigated.Physical measurements of deposited mass for each layer were performed with quartz crystal microbalance (QCM)

while the morphology of ultrathin films was observed by atomic force microscope (AFM).And the element and composite structure of PDDA/PVDF were determined by X-ray photoelectron spectroscopy (XPS) and gracing incident X-ray diffraction (XRD)

respectively.The surface resistivity and electric hysteresis loop of ferroelectric ultrathin films have been studied also.The results showed that the thickness of each layer for self-assembled PVDF ultrathin films on QCM substrate was about 7.5 nm

and the morphology of composite ultrathin films was uniform.The binding energy of F1s in composite ultrathin films was decreased 0.3 eV comparing with the poled PVDF films

which was caused by the distribution of negative charges as the re-dissolution of polymer.In addition

the surface resistivity was improved to over 1017 Ω#12539;cm for orderly self-assembly

and the remanent polarization was about 0.1 μC/cm2 for non-ferroelectric PVDF in PDDA/PVDF ultrathin films.