Synthesis of pectin-based graft copolymers with synthetic fragments of vinyl monomers using the triethylborane-oxygen initiating system

The study of trialkylborane as a component of the initiating system with oxygen was carried out using the example of graft polymerization of alkyl(meth)acrylate vinyl butyl ether copolymer units on pectin polysaccharide. The amine complex triethylborane-hexamethylenediamine was introduced into a boiling mixture of an aqueous solution of pectin in vinyl butyl ether, after which a solution of the active monomer, alkyl(meth)acrylate, containing methacrylic acid, was introduced by the compensation method to isolate triethylborane from the complex. As a result of synthesis from a mixture containing butyl acrylate, three immiscible parts were formed: organic, aqueous, and between them a “sponge” that did not dissolve in any of the phases. In the case of methyl methacrylate, only two parts were formed in the mixture: organic and aqueous. Water-soluble and organic polymers were dried under vacuum conditions to constant weight at T = 20-25 °C. Gravimetric analysis showed that the “sponge” was a mixture of water-soluble and organic polymers at 50:50 ratio. To do this, the dried polymers were dissolved alternately in water and vinyl butyl ether. Graft copolymers pectin-methyl methacrylate-vinyl butyl ether and pectin-butyl acrylate-vinyl butyl ether were isolated from the aqueous phase of the synthesized systems, in relation to the introduced acrylate. In comparison with the original pectin, the molecular weight of the water-soluble fraction increased significantly. Comparison of the IR spectrum of the graft copolymer pectin-methyl methacrylate-vinyl butyl ether with the IR spectra of pectin and the IR spectrum of pectin-methyl methacrylate indicated that all the bands characteristic of pectin, polymethyl methacrylate, and polyvinyl butyl ether were observed for the new polymer sample. Freeze-dried samples of pectin and pectin-methyl methacrylate-vinyl butyl ether graft copolymer were examined using scanning electron microscopy. A comparative analysis showed a change in the structure of pectin fibers as a result of its copolymerization with a copolymer of methyl methacrylate-vinyl butyl ether. The obtained data confirm the addition of synthetic polymers alkyl (meth) acrylate-vinyl butyl ether to the basis of the pectin macromolecule. New substances are polymer molecules containing natural and synthetic fragments with an ordered structure. Such compounds are promising as the basis for wound healing coatings.