Preparation and characterization of nanocomposites of polyamidoamine (PAMAM) dendrimers with molybdenum(VI) oxide (MoO_3)

摘要

The preparation and characterization of polymer nanocomposites is an important research area because of the significant changes in materials properties relative to the component phases or to conventional microscale or macroscale composites. Polyamidoamine (PAMAM)/moIybdenum(VI) oxide (MoO_3) nanocomposites were synthesized using an exfoliation/adsorption method and characterized by powder X-ray diffraction, thermogravimetric analyses, scanning electron microscopy and infrared spectroscopy. Generation 0 (GO) and generation 2 (G2) PAMAM forms nanocomposites with MoO_3 with either intercalate monolayers or bilayers, with resulting gallery expansions (Ad) of ～0.5 and ～ 0.7-0.8 nm, respectively. GO only forms monolayers whereas G2 forms mono and bilayers. The spherical PAMAM conformation in aqueous medium changes dramatically to a highly-flattened conformation within the intercalate galleries. Reaction temperature also affects the structure of the obtained G2 PAMAM nanocomposites. Bilayer nanocomposites obtained at 40 and 120 ℃ show Ad = 1.4 nm and 0.7 nm, respectively. Mixed phases were obtained at 60 ℃. The obtained nanocomposite compositions and structures are compared with previously-reported polymer/MoO3 nanocomposites.