1H-NMR study of maleic anhydride modified ethylene-diene copolymers
An alternative route for the preparation of polar polyolefins involving “site specific” functionalisation is presented. In this approach, the functionalisation of polyethylene is achieved by the combination of two well known processes: the copolymerization of ethylene with a non conjugated diene, followed by the reaction of the copolymer with maleic anhydride (MAH) via Alder Ene reaction. This route avoids the use of peroxides and consequently limits degradation and other undesirable reactions such as chain scission, crosslinking and coupling, usually occurring under free radical conditions. The molecular structure of the MAH modified ethylene-diene copolymer is investigated by spectroscopic techniques, such as FTIR and 1H-NMR, applied to the modified copolymer as well to model compounds and copolymers. The spectroscopic studies confirm that the functionalisation of the ethylene/5,7-dimethyl-1,6-diene (EDMO) copolymer proceeds mainly through the Alder Ene mechanism, under our experimental conditions, and provide data to elucidate the molecular structure of the modified MAH copolymer.
KeywordsFunctional polyolefins Alder Ene reaction Ethylene-diene copolymer Maleic anhydride
This work was supported by Foundation for Science and Technology—FCT, POCTI Program and FEDER support (Project POCTI/CTM/41408/2001). Ana I. Vicente acknowledges her fellowship. Thanks are also due to the National NMR Network—IST node (Portugal) for providing access to the 500 MHz spectrometer.
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