Facile, efficient functionalization of polyethylene via regioselective copolymerization of ethylene with cyclic dienes

Abstract

The copolymerizations of ethylene with cyclic dienes [dicyclopentadiene (DCPD) and 2,5-norbornadiene (NBD)] using bis(b-enaminoketonato)titanium complexesIn the presence of modified methylaluminoxane, these complexes exhibited high catalytic activities in the copolymerization of ethylene with DCPD or NBD, affording high molecular weight copolymers with unimodal molecular weight distributions. 1 H and 13 C-NMR spectra reveal ethylene/DCPD copolymerizations by catalysts 1a-c proceeds through the enchainment of norbornene ring. Catalysts 1a and 1c showed a tendency to afford alternating copolymers. More noticeably, catalysts 1b and 1c bearing bulky substituents on the ligands promote ethylene/NBD copolymerization without crosslinking, affording the copolymer containing intracyclic double bonds. The NBD incorporation as high as 27.2 mol % has been achieved by catalyst 1c. Moreover, the microstructures of the copolymers were further confirmed by the measurement of reactivity ratios and dyad monomer sequences as well as mean sequence lengths. The intracyclic double bonds of ethylene/DCPD or ethylene/NBD copolymers can be fully converted into polar groups such as epoxy, amine, silane, and hydroxyl groups under mild conditions. Convenient synthesis of hydroxylated polyethylene can be provided for the first time through the ring opening reaction of epoxide.

Preparation of novel cyclic olefin copolymer with high glass transition temperature

“…In this work, we report novel bulky cyclic olefins tricyclo[4.4.0.1 2,5 ]undec‐3‐ene (TUE) and tricyclo[6.4.0.1 9,12 ]tridec‐10‐ene (TTE), which are synthesized via Diels‐Alder reaction between cyclopentene (CPD) and cyclohexene (CHE) or CPD or cyclooctene (COE), respectively (Scheme ). By using bis(β‐enaminoketonato) titanium catalysts, which are demonstrated to display excellent ability toward the copolymerization of ethylene with cyclic olefins ( 1a : [PhNC(CH 3 )CHC(CF 3 )O] 2 TiCl 2 ; 1b : [PhNC(CF 3 )CHC(Ph)O] 2 TiCl 2 ), effective copolymerizations of ethylene with TUE or TTE have been achieved, affording novel COCs with high T g values at low cyclic olefin contents. For comparison, ethylene/tricyclo[4.3.0.1 2,5 ]deca‐3‐ene (TDE) copolymers (Scheme ) were also prepared in this work.…”

Living regioselective copolymerization of ethylene with nonconjugated bicyclic dienes using (salicylaldiminato)(β‐enaminoketonato) titanium catalysts

“…Among the catalysts based on Group 4 metals, titanium complexes have become one of the most important class catalysts for olefin polymerization 54–61. We previously reported complex 2a [PhNC(CF 3 )CHC(Ph)O] 2 TiCl 2 was able to produce ethylene/VNB or ENB copolymers selectively with high incorporations, but no living copolymerization behavior has been achieved because of the major chain transfer to aluminum during the polymerization process 42.…”

Preparation of cycloolefin copolymers of a bulky tricyclopentadiene

“…DCPD has two kinds of double bonds: NB‐type and cyclopentene‐type. The NB‐type double bond is much more reactive than the cyclopentene‐type one, and it is possible either to polymerize DCPD through ring opening metathesis polymerization (ROMP)20, 21 or to copolymerize it with ethylene with the cyclopentene‐type double bond remaining intact 22–24. The reactivity of the cyclopentene‐type double bond is about one‐tenth of the NB‐type one 25.…”