Poly(amic acid)–clay nacrelike composites prepared by electrophoretic deposition

Poly(amic acid) (PAA)–clay nacrelike composite films have been prepared by electrophoretic deposition of an emulsion of PAA, which was synthesized from pyromellitic dianhydride and 4,4′-dianminodiphenyl ether (ODA), containing various loadings of ODA-modified montmorillonite (MMT). The layered silicate was intercalated through reacting with PAA, and the ordered layered assembly of the PAA–MMT composite films was successfully accomplished, as conformed by Fourier transform infrared analysis and x-ray diffraction. The structural characterization of the films was supported by scanning electron microscopy, which displayed an ordered layered structure. The thermogravimetric analysis showed the content of the ODA-modified clay in PAA–MMT composite films that changed from 14.3 to 32.1 wt% and the improved thermal properties of the composite films. The mechanical properties of the composites were measured by tensile test. It was found that the modulus and strength of the composite films were greatly improved compared to those of the pure polymer film. An increment of about 155% in the modulus and 40% in the tensile strength were obtained from the composite films.