Polyimide/Organo-Montmorillonite Nanocomposites: A Comparative Study of the Organoclays Modified With Aromatic Diamines

Six organophilic clays have been obtained through cation-exchange between sodium montmorillonite (Na(+-)Mt) and the hydrochloride salts of aromatic diamines (DA1-6). The results obtained by thermogravimetric analysis (TGA) showed that the organophilic clays start to decomposition within 150-340 degrees C, which shows that they are thermally stable compared with conventional montmorillonite modified with aliphatic long-chain quaternary alkyl ammonium salts. The highest thermal stability and interlayer basal spacing were observed for the organoclay obtained from 3,3-sulfonyl dianiline (DA2), and therefore it was chosen for preparing clay/polymer nanocomposite materials (CPN). Polyimide/clay nanocomposite materials consisting of benzophenone-3,3,4,4-tetracarboxylic dianhydride (BTDA) and 2-(5-(3,5-diaminophenyl)-1,3,4-oxadiazole-2-yl)pyridine (POBD) were also obtained by an in situ polymerization reaction through a thermal imidization. DA2-Mt was used as filler at different concentrations. Both the thermal stability and the glass transition temperature (T-g) are increased with respect to pure polyimide (PI) at low clay loadings. At high clay concentrations, the organoclay particles make aggregate and as results of this phenomena T-g and thermal stability are decreased. POLYM. COMPOS., 36:613-622, 2015. (c) 2014 Society of Plastics Engineers