Ethene/1‐olefin blocky copolymers were obtained through nonliving insertion copolymerizations promoted by an isospecific single site catalyst. Propene or 4‐methyl‐1‐pentene were copolymerized with ethene with metallocenes endowed with different stereospecificity in propene polymerization: (i) aspecific “constrained geometry” half‐sandwich complex, {η1:η5‐([tert‐butyl‐amido)dimethylsilyl](2,3,4,5‐tetramethyl‐1‐cyclopentadienyl)}titanium dichloride [Me2Si(Me4Cp)(N‐tBu)TiCl2] (CG), (ii) moderately isospecific rac‐ethylenebis(indenyl)zirconium dichloride [rac‐(EBI)ZrCl2] (EBI), (iii) slightly more isospecific hydrogenated homologue, rac‐ethylenebis(tetrahydroindenyl)zirconium dichloride [rac‐(EBTHI)ZrCl2] (EBTHI), (iv) highly iso‐specific rac‐[methylenebis(3‐tert‐butyl‐1‐indenyl)]zirconium dichloride [rac‐H2C‐(3‐tBuInd)2ZrCl2] (TBI), (v) most isospecific rac‐[isopropylidene‐bis(3‐tert‐butyl‐cyclopentadienyl)]zirconium dichloride [rac‐Me2C‐(3‐tBuCp)2ZrCl2] (TBC). Copolymerizations were described by a 2nd order Markovian copolymerization model and data are proposed to correlate the formation of 1‐olefin sequences with catalytic site isospecificity, made by the cooperation of organometallic complex and growing chain. Blocky copolymers were prepared over wide ranges of compositions: with any of the isospecific metallocenes when 4‐methyl‐1‐pentene was the 1‐olefin and only with the highly isospecific ones (TBI, TBC) when propene was the comonomer. A penultimate unit effect was observed with TBI as the metallocene, whereas a 1st order Markov model described the ethene/propene copolymerization from TBC. A moderately isospecific metallocene, such as EBI, is shown to be able to prepare blocky ethene copolymers with 4‐methyl‐1‐pentene. These results pave the way for the synthesis of new ethene based materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2063–2075, 2010
O presente artigo propõe analisar a violência de gênero no Brasil a partir do conceito de guerra contra as mulheres, cujo objetivo está em compreender as violências machistas que se materializam nos corpos das mulheres intrinsecamente ligadas a violências políticas, econômicas, laborais, institucionais. A luz do neoliberalismo, que produz novas subjetividades, precariedade e explorações, e da crise sanitária decorrente da pandemia do vírus Covid-19, constata-se que as mulheres são as primeiras a sentir os impactos do vírus e os casos de incremento explícito dos índices de violência doméstica expõem a interconexão de violências, a qual precisa tornar elemento analítico sobre a condição de vida atual e as estratégias de resistência aos processos incisivos de precarização.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.