Effects of anion and solvent on properties of alternating ethylene/CO copolymer catalyzed by the Pd(II) complex

Alternating copolymerization of ethylene and carbon monoxide was carried out using (dppp)Pd(OAc)(2)/ anion complexes (dppp = 1,3-bis(diphenylphosphino)propane) with various anions and solvents. Catalytic activity in a protic solvent (methanol) was found higher than that in an aprotic solvent (acetone). When p-toluenesulfonic acid (p-TSOH) was used as an anion, molecular weight and melting temperature as well as the catalytic activity, increased with an appropriate combination of methanol and acetone instead of each methanol or acetone. The type of anion and solvent seemed important for catalytic activity and polymer properties. Catalytic activity decreased due to steric hindrance of alcohol in the order, methanol>i-butanol>t-butanol. Polymer properties such as molecular weight, melting temperature and crystalline structure as well as catalytic activity were significantly affected by the presence of water.