Acid-Base (Donor-Acceptor) Properties of Solids and Relations with Functional Properties

Abstract

Distribution of active surface centers (DAC) spectroscopy is applied to study acid-base properties of solids. Surface characteristics of solid influences interface interaction in which this solid participates. Efficient approach to consider such interactions is to view them as acid-base ones, since acid-base interactions determine adsorption and bonding of organic molecules to solid surface. Paper describes application of method to study surface properties of components of luminescent materials, catalysts, gas sensors, proton membranes and polymer composites, and it was shown that their functional properties strongly depend on distribution of acid-base active surface centers.

Dielectric properties of oligomeric diisocyanate based composites with barium titanate

“…It should be noted that percolation is a prerequisite for increase in the magnitude ε and minimization of tg δ of the composites of this type, which are structured as condensers with a subsequently connection of layers of different materials, whose total capacitance and permittivity depend on values of initial materials of isocyanate and BaTiO 3 by an irreversibly proportional law. Such nonlinear dependences of the dielectric characteristics on modification conditions of barium titanate, which make conditions for percolation in the system, have been earlier observed in similar composites based on cyanoethylated ether of polyvinyl alcohol [6][7][8][9][10][11]. The filler concentration of 35 vol.% corresponds to a transition to formation of a matrix & chain structure in an endless structure as accompanied by beginning general percolation, which corresponds to observed increase in permittivity.…”

“…In particular, increase in the permittivity ε and decrease in dielectric losses (tg δ) of the composites with ferroelectric fillers are observed at the most uniform distribution of filler particles in a matrix and at the presence of percolation (a spatial grid of bonds) between the filler particles due to amplification of a synchronized response of the distributed filler to impact by an electric field. The said effects have been studied in the papers [6][7][8][9][10][11] for the composites based on cyanoethylated ether of polyvinyl alcohol with barium titanate BaTiO 3 (which is a ferroelectric having one of the highest values ε), whose dielectric properties have been controlled by optimization of an amount of the input filler and modification of its surface with different additives (disperse oxides [7,8], a fullerenol [9], a graphene [10]), which provide amplification of the inter-phase interactions due to formation of specific function groups. It has been ascertained that dependences of the dielectric properties of the composites on a concentrations of the input additives are often nonlinear with sharp extremums and correlated to a content of certain centers on a filler surface and to uniformity of its distribution in the matrix, wherein an important role is played by fractal characteristics of distribution of the filler particles in the matrix [11].…”

Analysis of the Structure of Composite Systems by Means of Fractal Characteristics Using the BaTiO3–Fullerenol–CEPVA System as an Example

“…At the same time, establishing the relationship between the mathematical models describing the structure of composites and their target properties remains an important and largely unsolved problem. In [4][5][6][7], an integrated approach was proposed to control the electrical characteristics of polymer-inorganic composites, in particular, to increase the dielectric constant and to reduce dielectric losses by controlling the donor-acceptor interphase interactions in the filler-binder system, as well as by modifying the surface layer of ferroelectric fillers with nanocarbon additives. The maximum values of the dielectric constant of such composites were achieved by modifying barium titanate through precipitation of fullerenol from an aqueous suspension.…”

Effect of Electron-Beam Induced Nanostructuring on Surface Properties and Radioluminescence of ZnS:Cu,Br Phosphors

“…The effects of the distribution and redistribution of active centers on the surface of different photo-and electroluminescent phosphors according to acid-base and donor-acceptor properties, as well as a possibility to enhance the phosphor properties due to electron beam induced modification, was considered in a series of our earlier studies [11][12][13][14]. In this study, this concept was applied to a series of zinc sulfide based RL phosphors.…”