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Optical measurements showed that most of the systems studied show a
slight increase in optical density (D) in the sol- gel transition. This effect is less
pronounced in the reaction of hydrolysis and polycondensation TMOS pure,
most - the introduction of small additions of PVP and PVC. An exception to the
general rule is the system PVSZ TMOS + hell + water. For her, there was no
change in optical density ratios for all components and is probably due to the
small size of the scattering centers. We can assume that this is due to the
stabilization of the particle size of the PVA adsorption layer.
At the final stage of structure formation in the organic-inorganic systems in
the area of transition from a gel to a xerogel again a sharp increase in the optical
density, which in this case amounts to several units.
Calculation of turbidity spectra effective particle size of the dispersed
phase in transitions sol - gel and gel - xerogel showed that in both stages is
realized traditional behavior of dispersed systems - the particle size of the
dispersed phase increases and the number of particles per unit volume decreases.
The only difference in their values, so the average radius of scattering
centers formed in the gel, reaches a maximum value of about 170 to them, and
the range of sizes change upon concentrating system is from 0.3 to 1.5 microns,
i.e. becoming phase macroscopic dimensions.
Thus, phase transformations initiated by hydrolysis and polycondensation
of TMOS and subsequent evaporation of the solvent leads to successive
reconstructions phase the organization of organic-inorganic systems from nano-
to the macro level. This trend shows the change in optical density at all stages of
structure investigated. In forming the gel is formed, growth of the amorphous
silica particles, adsorption of macromolecules of a hydrophilic polymer on the
surface, and evaporating the solvent in step - secondary aggregation of particles.
The structure of organic-inorganic systems on the example of the
amorphous silica. Dispersing aerosil samples of silica from TMOS (hereinafter
designated - (5YU2) in the ultrasound field it possible to identify the individual
aggregates of particles and explore their fine structure by transmission electron
microscopy image processing was for waste technique that has allowed to build
the relative density radial distribution function near the interface. . The density
of the border in the middle of the field is almost constant, the length of the
interface for the (ZKT), 3-4 times higher compared with aerosil results were
used in the construction scheme of the structural body of the organization -
inorganic sorbent.
Mixtures of PVA + silicon and analysis of electron - microscopic images of
structures xerogels PVA-3+ (510e) and PVSZ + Aerosil showed that they are
characterized by a heterogeneous structure with poorly expressed relief. For
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