OBTAINING A COPOLYMER OF STYRENE AND Α-METHYLSTYRENE USING VARIOUS ANIONIC AND NON-IONIC EMULSIFIERS

A copolymer of styrene and α-methylstyrene was obtained by the method of emulsion copolymerization in the presence of an ammonium persulfate initiator and various emulsifiers at a mass ratio of the initial monomers of 70 : 30. The emulsifiers were used as ionic (sodium oleate, potassium oleate, potassium stearate, a mixture of oleate and potassium stearate), and non-ionic emulsifiers (OS-25 and OS-50). The yields of the copolymer in the case of using ionic emulsifiers were 74–85%, and the maximum yield was observed only when using a mixture of potassium oleate and stearate (1 : 1). When using nonionic emulsifiers OS-25 and OS-50, the yields of the copolymer were 75–90%, the highest yield was obtained when using emulsifier OS-50. The molar ratio of styrene and α-methylstyrene units, determined by 1H NMR spectroscopy, was 8 : 3. It was found by IR spectroscopy that the copolymer of styrene and α-methylstyrene obtained using potassium stearate has minimal residual amounts of emulsifier due to its low adsorption by the resulting copolymer . In the case of using sodium or potassium oleates and their mixtures, very weak characteristic frequency bands appear, which are characteristic of the carboxyl group of emulsifier molecules, which indicates their inclusion in the synthesized polymer chains as comonomers. In the case of using nonionic emulsifiers OS-25 and OS-50, the copolymer cannot be washed away from them, despite the fact that the emulsifier molecules are not covalently bonded to the copolymer. The good adsorption of emulsifier molecules on the hydrophobic surface of the copolymer is associated with the presence of hydrophobic alkyl and ethylene fragments in the structures of the molecules of these emulsifiers and the inability to ionize the terminal OH groups under normal conditions.