A theoretical study of the comonomer effect in the ethylene polymerization with zirconocene catalytic systems

Copolymerization of ethylene/unsaturated alcohols using nickel catalysts: effect of the ligand on the activity and comonomer incorporation

“…These results are in accordance with the tendency found in the literature [10][11][12][13] to consider that quantum-chemical calculations are able to help in the understanding of the processes involved and even on the screening of catalysts.…”

“…The molecular weight of a sample of PE obtained with the system 3-NiBr 2 /MAO under similar experimental conditions, except that a higher Al/Ni was used (Al/Ni = 2200) was found to be higher than that of sample R 66 (M n = 41.1 and PD = 3.5) [8]. Table 8 Number of branches of polyethylene samples determined by 13 the catalyst precursors were activated by MAO and H was protected with TMA. Fig.…”

Explaining the High Catalytic Activity in Bis(indenyl)methyl Zirconium Cation Using Combined EDA‐NOCV/QTAIM Approach

“…Concerning the local reactivity focused on the metal centre during the entire polimerisation process, there is no speculation on this assumption because the metal centre is the most reactive site on any metallocene methyl cation as inferred from experiments performed by Alt and Köppl [25] and several authors too [1–5,7–10,12,13] . Besides, we performed computational theoretical works [11,122,123] where we addressed several reaction pathways and we found that the main reactive site susceptible to coordinating an olefin is the metal centre as can be supported by other already published works [1–5,14–16,18,20,21,23] thus implying the local reactivity on Zr in the $${\left[ {{\rm{L}}_1 {\rm{L}}_2 {\rm{ZrCH}}_2 {\rm{CH}}_2 ({\rm{CH}}_2 )_{2\left( {n + 2} \right)} {\rm{CH}}_3 } \right]^ + }$$ cationic species should be kept constant or even increase without mattering the value of n (where n stands for the number of ethylene molecules inserted on the organometallic structure); otherwise, the polimerisation process would never happen.…”

“…Concerning the local reactivity focused on the metal centre during the entire polimerisation process, there is no speculation on this assumption because the metal centre is the most reactive site on any metallocene methyl cation as inferred from experiments performed by Alt and Köppl [25] and several authors too. [1][2][3][4][5][7][8][9][10]12,13] Besides, we performed computational theoretical works [11,122,123] where we addressed several reaction pathways and we found that the main reactive site susceptible to coordinating an olefin is the metal centre as can be supported by other already published works [1][2][3][4][5][14][15][16]18,20,21,23] thus implying the local reactivity on Zr in the L…”

Thermal and Dielectric Stability of Functional Photo-cross-linkable Carbazole-Modified Polypropylene

“…In our case, there are some disabling interactions between UDK molecules and metal sites that, seemingly, are not strong enough to counteract insertion enhancement, promoted by the activating interaction of a long-chain α-olefin. ,− The consequence is an apparent masking of the nitrogen effect of the UDK moiety, in contrast to what is observed for the copolymerization of propylene with 1-(undec-10-en-1-yl)- 1H -pyrrole, where the unflanked pyrrole ring allows a remarkable disabling interaction, that drives the copolymerization kinetics. , Accordingly, the high activity of metallocene catalysis is preserved at low contents of the polar comonomer in the feeding (ca. <0.015), as it is displayed in figure S4.…”