M. L. Bubnova

Control of crosslinking free-radical copolymerization of ethylene glycol dimethacrylate with alkyl methacrylates of various structures and macromolecular design of copolymers

The possibility of controlling the crosslinking free-radical copolymerization of ethylene glycol dimethacrylate with alkyl methacrylates of various structures and of the macromolecular design of the resulting copolymers through the use of small additives of cobalt porphyrin, which terminates polymer chain growth via catalytic chain transfer, has been studied. It has been shown that steric hindrances to the interaction of a propagating radical R* with pendant C=C bonds that are created by bulky substituents of dodecyl methacrylate provide an additional factor that impedes intrachain cyclization and crosslinking reactions that give rise to network structures.

Effect of branched copolymers on the kinetics of polymerization of MMA and the structure and properties of the resulting polymers

It has been shown that the free-radical polymerization of MMA carried out in the presence of branched PMMAs of various compositions and structures proceeds as a crosslinking process. Branched PMMAs containing reactive C=C bonds serve as weak crosslinking agents; polymers formed in their presence are rarely crosslinked macromolecular structures. The kinetic features of the polymerization of MMA performed in the presence of branched PMMAs and the structure and properties of the polymers are determined by the content of branched PMMAs in the starting monomer-polymer mixture and their structure and physicochemical characteristics.

Free-radical copolymerization of binary mixtures of vinyl monomers of various compositions: Initiation rate constants

For a number of vinyl monomers (styrene, butyl acrylate, vinyl acetate, and methyl-, butyl-, and lauryl methacrylates) and their mixtures with a divinyl (network-forming) monomer—triethylene glycol dimethacrylate—with the molar ratio of binary mixture components varying from 0 to 100%, initiation rate constants have been measured through the inhibition method with the use of 2,2,6,6-tetramethyl-1-piperidinyloxy as a counter of free radicals. Viscosities at various temperatures and activation energies for the viscous flow of the monomers under study have been estimated. The relationship between the initiation rate constants and the viscosity of the medium has been established. On the basis of this relationship, the mechanism for the exit of radicals from the cage has been interpreted within the framework of the Franck-Rabinowitch model with allowance made for effects associated with formation of intermolecular associates in the systems under study.

Mechanical and thermal properties of ternary alternating copolymers of carbon monoxide with olefins

Thermal properties and the deformational behavior of ternary alternating copolymers of carbon monoxide with ethylene and other olefins (propylene, 1-butene, styrene) with molecular masses of Mn = 1000–35000 and molar fraction of the third comonomer in the polymer chain from 0.02 to 0.70 were investigated. Temperatures of melting and glass transition are significantly affected by the composition of the products. Varying the nature of the third comonomer or the content of its units in the polymer chain and the molecular masses of terpolymers makes it possible to obtain materials with Young’s moduli of 0.003–3.090 GPa and elongations at break of 5–2000%.

Ethyl acrylate copolymers as promising porogens for the synthesis of polydimethacrylates with controlled porous structures

The crosslinking radical polymerization of triethylene glycol dimethacrylate in bulk in the presence of 0–40 wt % ethyl acrylate-based copolymers of various compositions is studied, and some structuralphysical properties of the crosslinked polymers are investigated. The quantitative characteristics of their porous structures, such as the specific surface areas and the total pore volumes, are measured via the low-temperature adsorption of nitrogen. During sol-gel analysis, polymer additives are removed from network polymers with the use of benzene and pores with sizes from 4 to 500 nm occupy their places. The maximum specific surface area is approximately 17 m2/g. It is found that the specific surface area and total pore volume depend on the content of the polymer additive in the initial composition.

Hydrodynamic characteristics of branched polystyrenes with varying content of a highly branched fraction

The branched polymers containing different amounts of the highly branched fraction are synthesized by the radical copolymerization of styrene and divinylbenzene under conditions of the reversible inhibition by 2,2,6,6-tetramethylpiperidine-1-oxyl. The branched polystyrenes are studied by size-exclusion chromatography combined with static light scattering, viscometry, and pulsed-field gradient nuclear magnetic resonance. The branched polymers prepared by living radical polymerization (in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl) feature reduced intrinsic viscosities and increased self-diffusion coefficients compared with their linear analogs. As the content of the highly branched fraction in the synthesized polymers grows, the Zimm contraction factor in toluene solution decreases to g′ = 0.13. The Kuhn-Mark-Houwink parameters for these polymers in toluene solution (a = 0.43) confirm the nonlinear architecture of macromolecules.

Radical polymerization of methyl methacrylate in the presence of low-molecular-weight poly(methyl methacrylate)

The kinetics of the bulk radical polymerization of methyl methacrylate and the structure and properties (physicomechanical and thermomechanical, as well as diffusion and sorption) of the polymers were examined in relation to the amount of low-molecular-weight poly(methyl methacrylate) added.

Macromolecular design of the network structure of copolymers of ethylene glycol dimethacrylate with methyl methacrylate using the catalytic chain transfer reaction

Abstract It has been shown that catalytic chain transfer reaction is an effective instrument for the macromolecular design of the network structure of copolymers of ethylene glycol dimethacrylate with methyl methacrylate. Copolymers of various macromolecular architectures - from networks to soluble branched low-molecularweight oligomers - have been produced using cobalt porphyrin as catalytic chain transfer agent. The influence of cobalt porphyrin on the kinetics of copolymerization, structure and properties of final copolymers has been studied.