Synthesis of Linear Block Polymers Based on a Series of Vinyl Monomers Using Macroinitiators with a Terminal Labile Boroxyl Group

Abstract

The synthesis of two copolymers of different nature for their use as macroinitiators, namely, butyl acrylate with vinyl butyl ether and methyl methacrylate with vinyl butyl ether, was carried out by adding an active monomer to an excess of a comonomer during its boiling in the presence of triethylborane. The organoelement co-initiator was isolated from the complex with hexamethylenediamine in a solution of vinyl butyl ether by adding methacrylic acid in proportion to the amount of amine in moles, together with acrylate. In this case, the oxidant of triethyl boron is the oxygen of the air remaining in the reaction mixture when boiling vinyl butyl ether, sufficient to oxidize triethyl boron. The copolymer samples, isolated from the reaction mixture and characterized by GPC in respect of their molecular weight parameters and by IR as regards composition, were redissolved in vinyl butyl ether, a portion of ethylhexyl acrylate monomer was added and the mixtures were thermostated for four hours. The experimental results thus obtained indicate the formation of block copolymers using copolymers of vinyl monomers (butyl acrylate with vinyl butyl ether and methyl methacrylate with vinyl butyl) as macroinitiators. The mass was determined for the synthesized block copolymers, the composition and molecular mass pa-rameters were investigated. The weight of the initial samples during the synthesis almost doubled for both macroinitiators. Other characteristics of the block copolymers of butyl acrylate-vinyl butyl ether with ethylhexyl acrylate-vinyl butyl ether and methyl methacrylate-vinyl butyl ether with ethyl hexyl acrylate-vinyl butyl ether differ in many ways. In the case of the initial copolymer of butyl acrylate with vinyl butyl ether, the value of the number-average molecular weight increased significantly and the polydispersity coefficient decreased. For the initial copolymer of methyl methacrylate with vinyl butyl, the changes in molecular weight parameters are much smaller. This is due to the nature of the selected acrylic monomers. It is important that a new block consisting of monomer units of ethylhexyl acrylate and vinyl butyl ether continues to maintain the ratio of monomer units close to equimolar, as a result of block copolymerization. Such polymer compounds are efficient in lubricating oil thickeners with high resistance to mechanical degradation.