The hybrid guest-host nanocomposite films based on poly (ethylene oxide) (PEO) and molybdenum doped vanadium pentoxide (V0.975Mo0.025)2O5nH2O were prepared by sol-gel and hydrothermal reaction via a two-part process. The electrical properties along and across V-O layers have been evaluated. The results indicate that the proper amount of PEO can increase the electrical conductivity of the films. The electrochromism of the films were investigated by cyclic voltammetry, the ex-situ transmission spectra and photographs. The films display a reversible multichromism (orangegreenbluebrown) upon Li+ion insertion/extraction.
Large-mesopore silica films with a narrow pore size distribution and high porosity have been obtained by a sol–gel reaction of a silicon oxide precursor (TEOS) and using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers as templates in an acidic environment. PS-b-PEO copolymers with different molecular weight and composition have been studied in order to assess the effects of the block length on the pore size of the templated silica films. The changes in the morphology of the porous systems have been investigated by transmission electron microscopy and a systematic analysis has been carried out, evidencing the dependence between the hydrophilic/hydrophobic ratio of the two polymer blocks and the size of the final silica pores. The obtained results prove that by tuning the PS/PEO ratio, the pore size of the templated silica films can be easily and finely predicted.
AbstractPolyurethanes based on poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, succinic or citric acid, and ethyl ester L-lysine diisocyanate were synthesized and characterized by FT-IR and GPC. Wetting properties were evaluated by contact angle determinations. The critical micelle concentration was determined from surface tension measurements. Their abillity to undergo self-aggregation and temperature induced gelation was investigated through dynamic oscillatory measurements. The gelation point, sol-gel transitions, and gel structure are influenced by polymer structure, composition, molecular weight, concentration, and heating rate.
From Spherical Mesopores to Worm-Shaped Mesopores: Morphology Transition in Titania-Polystyrene-b-poly(ethylene oxide) Composite Films with Increasing Sol-Gel Reaction Time