SYNTHESIS OF COPOLYMERS OF STEARYLMETHACRYLATE AND STEARYLACRYLATE WITH N-SUBSTITUTED ACRYLAMIDES IN THE PRESENCE OF REVERSIBLE CHAIN TRANSFER AGENTS AND STUDY OF THEIR EFFECT ON THE LOW-TEMPERATURE PROPERTIES OF DIESEL FUEL

Abstract

The features of copolymerization of stearylacrylate (SA) and stearylmethacrylate with N-isopropylacrylamide and N,N-dimethylacrylamide in the presence of dibenzyltrithiocarbonate and 2-cyanoisopropyldodecyltrithiocarbonate as agents of reversible chain transfer have been studied. The choice of agents of reversible chain transfer (RAFT-agents) is due to the fact that sulfur-containing compounds with cyanoisopropyl radicals are most effective in the polymerization of methacrylic monomers, while benzyltrithiocarbonates are more active in the polymerization of acrylic monomers, as well as styrene and acrylonitrile. It has been established that polymerization of stearyl methacrylate (SMA) in the presence of RAFT-agents proceeds without a gel effect up to a high conversion. At the same time, although polystеarylmethacrylate samples are characterized by relatively high values of polydispersity coefficients (Mn/Mw) for controlled radical polymerization processes, they are nevertheless somewhat lower than for polymers of similar conversion synthesized in the absence of chain transfer agents. It has been shown that the process of copolymerization of stearyl acrylate and stearylmethacrylate with N-isopropylacrylamide and N,N-dimethylacrylamide in the presence of dibenzyltrithiocarbonate and 2-cyanoisopropyldodecyltrithiocarbonate proceeds without gelation to high conversions. The synthesized copolymers are characterized by a relatively narrow molecular weight distribution: the polydispersity coefficients of polymer samples vary from 1.18 to 1.57 in the case of using N-isopropylacrylamide and from 1.21 to 1.47 when using N,N-dimethylacrylamide as a comonomer to higher alkyl acrylates, which is typical for processes of radical polymerization proceeding in a controlled manner. At the same time, the synthesized copolymers exhibit a significant depressant effect when they are introduced into diesel fuel at a concentration of 1600 ppm. It has been established that copolymers of stearylmethacrylate and stearylacrylate with polar nitrogen-containing monomers have a more effective effect on the low-temperature properties of diesel fuel than homopolymers of stearylmethacrylate and stearylacrylate. At the same time, additives based on copolymers of stearylmethacrylate with N-isopropylacrylamide with a composition of 70/30 mol.% and stearylacrylate with N-isopropylacrylamide with a composition of 20/80 mol.% had the most significant effect on the low-temperature characteristics of the fuel.