Copolymerization Of Styrene And Maleic Anhydride Under Different Solvent Conditions

Styrene-maleic anhydride random copolymer was successfully synthesized in the green solvent dimethyl carbonate.The effects of solvent concentration,monomer ratio,polymerization temperature and initiator concentration on the molecular weight,conversion and maleic anhydride content of styrene-maleic anhydride random copolymer were discussed.Furthermore,the sequence structure and thermal properties of styrene-maleic anhydride random copolymer were analyzed by FTIR,¹³C-NMR,DSC and TG.The product result obtained by polymerization under the dimethyl carbonate system showed that the solvent concentration had a limited effect on the conversion,remained at about 73%,and the polymer molecular weight was low.With the increase of the solvent concentration,the molecular weight increased from 13,000to 19,000 and the maleic anhydride content varies between 16%and 31%.The results came from DSC and TG showed that the product was a pure styrene-maleic anhydride random copolymer rather than a blend system.The styrene-maleic anhydride random copolymer obtained by the polymerization in the conventional acetone system had a molecular weight of about 30,000,compared with the dimethyl carbonate system,which was about twice of the product under the dimethyl carbonate system,and the yield was similar,both are floating around 70%.The products of random copolymer in acetone system had a slightly higher content of MAH and a large amount of MSM structure in the molecular chain,meanwhile,product obtained by dimethyl carbonate system was mainly composed of SSS sequence accompany the sequence structure of SSM and MSS was similar and better degree of randomness.The product obtained under the dimethyl carbonate system had a thermal decomposition temperature of 450°C which was slightly lower than 470°C of the product obtained under the acetone system.The introduction of polar green solvent,DMSO into the DMC system improved the poor solubility of the non-polar solvent DMC to maleic anhydride,furthermore,DMSO was easy to recovery and recycle,which could keep the greenness of the polymerization system.The introduction of a small amount of DMSO could greatly increase the molecular weight of the product under DMC and the molecular weight up to 41,741,simultaneous maintain a narrow molecular weight distribution.