Preparation and characterization of polyimide/modified layered double hydroxide nanocomposites

Polyimide (PI)/modified layered double hydroxide (m-LDH) nanocomposites were prepared in this study. For this work, m-LDHs were prepared from layered double hydroxides (LDHs) through an anionic exchange reaction with pyromellitic dianhydride (PMDA), succinic acid or terephthalic acid. PMDA and 4,4'-oxydianiline were used to make the poly(amic acid) precursor for PI. X-ray diffraction and transmission electron microscopy measurements confirmed that the PMDA-modified LDH (PMH) and terephthalic acid-modified LDH (TMH) were well dispersed in the PI matrix. For the succinic acid-modified LDH, some of the LDH was intercalated with the succinic acid molecules but most maintained its original structure. Thus, the PI/PMH and PI/TMH nanocomposites exhibited improved mechanical, thermal and electrical properties compared to pure PI. The PMH has aromatic groups and is expected to have better pi - pi interactions with the PI chains than the other m-LDHs. Thus, the PI/PMH nanocomposites exhibited the best properties among the nanocomposites investigated. (C) 2010 Society of Chemical Industry