ИСТИНА

Solvent crazing is an approach for loading the polymer matrices by different organic and inorganic substances and for the preparation of composites with high mutual dispersity of components. Hybrid materials with uniform and layer filler disposition within/on the matrices were obtained by changing the structure of a crazed polymer and a way of filler introduction. In this work an interesting method of the polymer/silica nanocomposite preparation based on the commercial films of isotactic PP, HDPE and PET was described. Usage of reactive substances as crazed media allowed us to carry out a chemical modification within the polymer pores [1, 2]. Hyperbranched polyethoxysiloxane (HPEOS) and tetraethoxysilane (TEOS) were used as crazing liquids and silica precursors. Hydrolytic polycondensation of precursors in the presence of an acid or basic catalyst was carried out in polymer matrices at room temperature and isometric condition. The amount of filler in polymeric matrix does differ considerably depending on the precursor content and varies from 5 to 35 wt.%. The dispersity of silica particles and composite morphology depend on the type of a polymer and precursor and hydrolysis conditions. When HPEOS is used as precursor the composite material consists of two interpenetrating networks: polymer network consisting of oriented fibrils with a diameter of 6-8 nm and silica. The structure of composite materials obtained from TEOS and HPEOS solutions with alcohol (e.g. isopropanol or n-butanol) is alternative. The main part of silica-gel turns out to be concentrated on specimens’ surfaces, forming a continuous layer. In polymer’s volume spherical nanoparticles with a diameter of 5-150 nm are discretely spread. The influence of the structure of obtained polymer-silica composites on different properties (mechanical, sensory, proton conductivity) was investigated. It was found that the properties of materials contained 10-20 wt.% of SiO2 were drastically changed. The nanocomposites obtained are promising as materials with special (conductive, thermal, sensor, etc.) properties. In addition, the removal of the polymer matrix allows to obtain a porous silica plate with a high volume porosity of 1.5 cm3/g and specific surface area of 175-310 m2/g.