Papers by Author: Mihaela Olaru

Abstract: A novel silver/polysulfone nanocomposite membrane was prepared by a convenient ultraviolet irradiation technique, through in situ reduction of silver salt (AgNO3) added to a solution of commercial UDEL polyethersulfone dissolved in N-methyl-2-pyrrolidinone (NMP). The UV-reduction of Ag+ to Ag0 nanoparticles was confirmed by means of UV-vis spectroscopy, from aggregation phenomena. The effects of dispersion of silver nanoparticles within polysulfone matrix were investigated by means of ATR-FTIR, dynamic mechanical thermal analysis and differential scanning calorimetry. Using X-ray diffraction, it was shown that annealing produced silver crystallites of 70-90 nm across, which are partially textured in “sheetlike” {110} planes.

Abstract: The aim of the study was to synthesize and characterize silsesquioxane-based hybrid nanocomposites with self-assembling properties to be used in monumental stone conservation. Through radical polymerization of 3-(trimethoxysilyl)propyl methacrylate, a monomer that contains both methacrylate and silica phases, in the presence of a primary amine surfactant, at different silica precursor:ethanol molar ratios, new types of hybrid nanocomposites, in which silica was dispersed as domains with typical sizes in the nanometer range, were obtained. The self-assembling properties of the synthesized composites have been ascribed to the supramolecular assembling abilities of the surfactants, as well as to the combination of linear, ladder, and cagelike fragments of silsesquioxane type. The incorporation of surfactant within the sol-gel derived matrix may also lead to the obtaining of compounds that avoid cracking of the hybrid gel while drying inside the stone.