FREE-RADICAL COPOLYMERIZATION IN THE PRESENCE OF LEWIS-ACIDS .3. ALTERNATING COPOLYMERIZATION OF BUTYL ACRYLATE AND STYRENE IN THE PRESENCEOF AL2ET3CL3 - SOLVENT EFFECT

Photo-initiated alternating copolymerization of butyl acrylate (BA) an d styrene (St) in the presence of AI2Et3Cl3 was investigated in tetrac hloroethylene (TCE) and toluene (TOL) solution. The results showed tha t copolymers with equimolar compositions were obtained over a wide ran ge of reactant composition. The C-13 nuclear magnetic resonance spectr um confirmed their alternating structure. Solvent could greatly affect kinetic behaviour, in TCE solution, the optimum rate of copolymerizat ion was observed near equimolar monomer ratio; while in TOL solution t he rate of copolymerization increased rapidly at lower [BA], tended to a constant rate at higher [BA] and increased slightly with increasing [St]. Electron spin resonance spectra indicated that the St radical w as the only one to be detected. The effect of solvent as well as Lewis acid on alternating mechanism is also discussed.