cs9b01174_si_001.pdf (630.82 kB)
Randomly Functionalized Polyethylenes: In Quest of Avoiding Catalyst Deactivation
journal contribution
posted on 2019-07-30, 14:46 authored by Miloud Bouyahyi, Younes Turki, Akhilesh Tanwar, Lidia Jasinska-Walc, Rob DuchateauWell-defined
randomly functionalized polyolefins produced by catalysis
form an interesting class of polymers with great potential for various
applications. One of the major challenges for the production of these
materials forms the incompatibility of the commonly used electrophilic
group 4 metal based catalysts and the desired nucleophilic, especially
protic functionalities like hydroxyl and carboxylic acid groups. Although
pacification of the protic functionality remains necessary, it was
found that lowering the oxidation state of a constrained geometry
type of catalyst from Ti(IV) to Ti(III) turned the catalyst unexpectedly
tolerant to a wide variety of aluminum alkyl pacified, hydroxyl-functionalized
olefin comonomers. The catalyst’s tendency to undergo chain
transfer to aluminum, which was found to be intensified by the presence
of aluminum alkyl pacified, hydroxyl-functionalized comonomers, can
be efficiently suppressed by the addition of a sterically hindered
phenol such as 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT). Surprisingly,
the addition of BHT also increases the catalyst’s affinity
to incorporate these functionalized comonomers.