Binary cerium(IV) tert-butoxides-dialkylmagnesium systems: Radical versus coordinative polymerization of styrene

In situ generated half-lanthanidocene based catalysts for the controlled oligomerisation of styrene: Selectivity, block copolymerisation and chain transfer

“…All alkyl fragments of n-butylethylmagnesium introduced are involved in the chain transfer, highlighting a process which can be considered as a polystyrene catalyzed chain growth on magnesium, similar to that observed between lanthanidocene catalysts and magnesium dialkyl during ethylene polymerisation [31]. If polyethylene catalyzed chain growth (CCG) [32] on zinc has also been achieved, polystyrene chain transfer to aluminium [33,34] and reversible transfer to magnesium [13,16] occurred only with a partial transfer efficiency. The mechanism of the reaction is summarized in Scheme 1.…”

“…A1 13. C NMR spectra of polystyrene (400 K in tetrachloroethane-d 2 ) in the phenyl ipso carbon region corresponding to atactic polystyrene (a) and syndiotactic-rich polystyrene synthesized using the Cp*Nd(BH 4 ) 2 (THF) 2 /n-butylethylmagnesium combination.…”

Coordinative Chain Transfer Polymerization

“…The most commonly used CTA for styrene CCTP are based on magnesium 4; [46][47][48][49][50][51][52] and aluminum alkyls. [53][54] One of the problems associated with styrene CCTP is the need for high temperatures that leads to the occurrence of radical polymerization.…”

End-capped Oligomers of Ethylene, Olefins and Dienes, by means of Coordinative Chain Transfer Polymerization using Rare Earth Catalysts

“…As already mentioned for α-olefins, the activity of the decamethylmetallocene RE / Mg system was observed as negligible for the insertion step of styrene in a polymerization catalytic cycle. Higher temperature gave effective chain transfer of oligostyrene on dialkylmagnesium, but with competitive radicalar and/or anionic mechanisms besides the coordination one [45][46][47][48]. By switching from Cp* to other ligands, a stereoselective CCTP process yielded near-perfect syndiospecific and isospecific oligostyrenes end-capped with magnesium [49][50][51].…”