Copolymerization of Ethylene with 1-Butene and Norbornene to Higher Molecular Weight Copolymers in Aqueous Emulsion

Ethylene/norbornene and ethylene/1-butene copolymerization with nickel(II) salicylaldiminato complexes [{κ 2 - N, O -6-C(H) N(2,6-R 2 C 6 H 3 )-2,4-R‘ 2 C 6 H 2 O}NiMe(pyridine)] ( 1a, R = 3,5-Me 2 C 6 H 3, R‘ = I; 1b, R,R‘ = 3,5-(F 3 C) 2 C 6 H 3; 1c, R = 3,5-(F 3 C) 2 C 6 H 3, R‘ = I; 2, R = i Pr, R‘ = I) were studied in toluene as a reaction medium and in emulsion, the latter affording polymer dispersions. High molecular weight copolymers ( M n > 10 4 g mol -1 ) are formed. Incorporation of ethylene is much preferred over butene incorporation, X Bu / x Bu ∼0.05 under typical reaction conditions, by comparison incorporation of the strained olefin norbornene is higher, X NB / x NB ∼0.25 ( X = comonomer mole fraction in polymer; x = comonomer mole fraction in reaction mixture). Dispersions contained copolymers with up to 6 mol % comonomer (12 wt % for 1-butene; 20 wt % for norbornene). Incorporation of a few mol % of norbornene strongly decreases polymer crystallinity, which enhances the film forming properties of dispersions. Microstructure analysis by 13 C NMR shows that butene is incorporated in a 1,2-, 1,3- and 1,4-fashion. Whether 1,2- or 1,3-incorporation is predominant depends on the catalyst (nature of R).