Copolymerization of ethene with methyl acrylate and ethyl 10-undecenoate using a cationic palladium diimine catalyst

Abstract

The cationic palladium catalyst [(ArN=C(Me)C(Me)N=Ar)Pd(CH3)(NC—CH3)]+BAr'4- (Ar = 2,6-C6H3(CH(CH3)2); Ar' = 3,5-C6H3(CF3)2) (DMPN/borate) was applied in ethene homopolymerization as well as ethene copolymerization with polar monomers such as methyl acrylate and ethyl 10-undecenoate. Both ethene homo- and copolymerization afforded amorphous, branched polyethenes with glass temperatures around –65°C and very similar high degree of branching (105 branched C/1000C), which was independent of temperature and ethene pressure. Copolymerization with polar comonomers gave polyethylene containing both alkyl and ester-functional alkyl side chains. The ratio of both types of short chain branches was influenced by the feed concentration of polar monomer. In the presence of sterically hindered phenols (e. g., 2,6-di-tert-butyl-4-methylphenol (BHT)) and tetramethylpiperidine-N-oxyl radical (TEMPO) acrylate homopolymerization was prevented. BHT addition promoted both catalyst activity and methyl acrylate incorporation significantly. Polymerization reaction, polymer microstructures and polymer properties of polar and non-polar branched polyethenes were investigated.