Chemical plasticizing of polyacrylonitrile (PAN) was carried out by copolymerization of acrylonitrile with other monomers such as methacrylic esters: vinyl acetate, vinyl benzoate, styrene, and butyl vinyl ether. We identified and analyzed parameters of PAN, polymer modifiers and their macromolecules as polymethyl methacrylate (PMMA), polybutyl methacrylate (PBMA), polyvinyl acetate (PVA), polyvinyl benzoate (PVB), polystyrene (PS), and polyvinyl butyl ether (PVBE).This article reports the method of chemical plasticizing of polar chain polymer (PAN) by the reduction of polar parts and tuning the dipole moment value of the copolymer links.