Boris Zaitsev

Proton-transfer polyaddition reactions in syntheses of linear, branched, and functionalized poly(p-divinyl aromatics). I. Synthesis, kinetics, and mechanism of formation of linear unsaturated poly[bis(p-vinylphenyl) ether]

A peculiar step-growth (cationic) polymerization of bis(p-vinylphenyl) ether (BVPE) in nonpolar or slightly polar aromatic solvents in the temperature range from 70 to 150°C in the presence of 2.5–5.0 mmol/L of p-toluenesulfonic acid has been studied. Optimum polymerization conditions were found. New linear unsaturated polymers of BVPE with terminal vinyl groups and weight-average molecular weight from 1500 to 10,000 were obtained. The structure and the formation mechanism of these oligomers and polymers were established, and the accompanying side reactions were considered. The rate constants were measured for eight temperatures, and the activation energy was found to be −42 kJ/mol. The optimum polymerization temperature was about 80°C.

Heat-resistant and strong glassy network copolymers of aromatic ethers (Rolivsans) containing terminal vinyl and methacrylate groups with maleic anhydride

Three-dimensional radical copolymerization of multicomponent systems consisting of vinylaromatic ethers and methacrylates of secondary alkylaromatic alcohols (diols) with maleic anhydride was studied. Heat-resistant and strong polymeric materials and composites were prepared from copolymers of Rolivsans with maleic anhydride.

Heat-resistant network copolymers of unsaturated polyesters with 4,4′-divinyldiphenyl dioxide

The effect of a heat-resistant cross-linking agent, 4,4′-divinyldiphenyl dioxide, on the resistance to thermal oxidation and on physicomechanical properties of its copolymers with polyethylene glycol maleate phthalate and triethylene glycol dimethacrylate and of reinforced plastics based on them was studied.

Efficient mode conversion transducers for use in ultrasonic flow meters

This paper shows for the first time that a mode coupling transducer (MCT) based on coupling between plate acoustic waves and bulk acoustic waves can be used to realize high efficiency, wide bandwidth device for generating and detecting acoustic waves in fluids. Preliminary experiments show that two way conversion loss (conversion of energy from plate to bulk wave and back from bulk to plate wave) as low as 3 dB can be obtained. Further work is needed to determine the parameters governing this loss. The insertion loss of the IDTs used in our initial device was 12 dB. Using unidirectional transducers (UDTs) and proper tuning and matching this loss can be reduced to below one or two dB [5]. Thus overall insertion loss of a few dB can be achieved. The high efficiency, wide bandwidth, and low cost of the mode coupling transducer makes it an attractive device for many applications.

Heat-resistant network copolymers based on rolivsans modified with aromatic diamines

Thermochemical transformations of rolivsans with aromatic diamines were studied by IR and NMR (1H, 13C) spectroscopy and by dynamic mechanical, thermal, and elemental analysis. The heat resistance of rolivsans is considerably enhanced by their modification with small additions (10 ± 5%) of an aromatic diamine with curing at 150–300 (320)°С.

High-Temperature transformations of aromatic diamines in the Rolivsan matrix

The formation mechanism, structure, and properties of new network copolymers prepared by thermochemical transformations of Rolivsans with aromatic diamines were studied by IR, 1Н NMR, and 13С NMR spectroscopy and by dynamic mechanical, thermal, and elemental analysis.

Novel polycondensation method of improving high-temperature properties of microheterogeneous rolivsan copolymers modified by inserting epoxy and imide bridges between spherical microdomains

Rolivsan thermosetting resins (ROLs) (low-viscosity solvent-free compositions including (di)vinylaromatic ethers and thermosensitive (di)methacrylates) were modified by low amounts of polyfunctional compounds (epoxy resins (ERs) and aromatic diamines (DAs)). Thermochemical transformations in modified ROLs give novel glassy densely cross-linked copolymers with increased high-temperature strength and thermo-oxidative stability. It was revealed that copolymers obtained at different ROLs/ERs and ROLs/DA mixing ratios (which were varied over a wide range) and different heat treatment regimes have various compositions, cross-link densities, chemical, topological, and morphological structures. Structural features of these copolymers were studied by Infrared spectroscopy, dynamic mechanical, thermal, and elemental analyses; the temperature dependences of flexural strength were also obtained. Morphological pattern of the cured ROLs is typical of microheterogeneous polymers where spherical highly cross-linked microdomains (polymer grains) with high Tg are weakly bound by less densely cross-linked defective (intergrain) polymer layers with lower Tg. On the basis of the data obtained in the studies of thermochemical transformations in ROLs/ERs and ROLs/DA blends, the new approach to improving thermal stability and heat resistance of thermosetting resins was developed. We suggest using intergrain layers in microheterogeneous cross-linked polymers as “microreactors” which include target polyfunctional compounds for various high-temperature polymerization and polycondensation reactions.

Heat-resistant network copolymers of triethylene glycol dimethacrylate with 4,4′-divinyldiphenyl oxide and monomer-oligomer formulations based on it

Thermal and physicomechanical properties and thermal oxidative aging at 250 and 300°C of triethylene glycol dimethacrylate homopolymer and copolymers with divinyl aromatic compounds and of glass-cloth laminates based on these polymers were studied.

Heat-resistant glass-reinforced plastics based on unsaturated polyester resins modified with divinyl aromatic compounds

The effects exerted by elevated temperatures and thermal oxidative isothermal aging in air at 150, 200, 250, and 300°C on the thermal and physicomechanical properties of glass-reinforced plastics based on copolymers of unsaturated polyester resins with divinyl aromatic compounds and formulations was studied.

Dielectric, physicomechanical, and thermal properties of polymer films prepared from cured 4,4′-divinyldiphenylalkanes

The dielectric, physicomechanical, and thermal properties of crosslinked polymer films prepared by copolymerization of divinyl aromatic monomers and oligomers containing methylene bridges between benzene rings were studied.