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Franco M Rabagliati - One of the best experts on this subject based on the ideXlab platform.
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Styrene/substituted styrene copolymerization by Ph2Zn-metallocene-MAO systems : homo-and copolymerization of p-methoxystyrene with styrene
Polymer International, 2020Co-Authors: Franco M Rabagliati, Héctor E. Muñoz, Gabriela V. Mardones, Francisco J. RodríguezAbstract:BACKGROUND: The present work is part of a general study regarding the homo- and copolymerization of styrene using Diphenylzinc–additive initiator systems, with the aim of improving the properties of commercial atactic polystyrene. The study is focused on syndiotactic polystyrene and/or copolymers of styrene (S) with substituted styrene, styrene derivatives or various α-olefins. This research has been ongoing over the last 15 years. RESULTS: The reported experiments show that binary metallocene–methylaluminoxane (MAO) and ternary Ph2Zn–metallocene–MAO, depending on the metallocene employed, are capable of inducing both homo- and copolymerization of styrene and p-methoxystyrene (p-MeOS). The results indicate that for a styrene/p-MeOS mole ratio with p-MeOS > 25% the product obtained has only a minor incorporation of styrene units. The efficiency of the metallocenes studied follows the order bis(n-butylcyclopentadienyl)titanium dichloride ((n-BuCp)2TiCl2) > indenyltitanium trichloride (IndTiCl3) > Cp2TiCl2. CONCLUSION: Metallocenes (n-BuCp)2TiCl2, Cp2TiCl2 and IndTiCl3 in binary systems combined with MAO, as well as in ternary systems combined with Ph2Zn and MAO, induce the homopolymerization of p-MeOS and its copolymerization with styrene. The styrene/p-MeOS copolymer obtained was enriched in p-MeOS with respect to the initial feed, in agreement with the I+ inductive effect of the methoxy group in the para position of styrene. As already reported, the role of Ph2Zn was nullified by its complexation with the p-MeOS comonomer. Copyright © 2008 Society of Chemical Industry
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STYRENE/STYRENE-DERIVATIVE COPOLYMERIZATION BY PH2Zn-METALLOCENE-MAO SYSTEMS: HOMO- AND COPOLYMERIZATION OF á-METHYLSTYRENE WITH STYRENE
Journal of The Chilean Chemical Society, 2020Co-Authors: Franco M Rabagliati, Héctor E. Muñoz, Gabriela V. MardonesAbstract:The copolymerization of styrene with α-methylstyrene has been tested using combined metallocene-MAO initiator systems with and without Diphenylzinc. The metallocenes used were biscyclopentadienyltitanium dichloride, Cp 2 TiCl 2 , bis(n-butylcyclopentadienyl)titanium dichloride, (n-BuCp) 2 TiCl 2 , and the halfsandwich metallocene indenyltitanium trichloride, IndTiCl 3 . The results indicate that both binary metallocene-MAO, and ternary Ph 2 Zn-metallocene-MAO systems are capable of polymerizing α-methylstyrene to poly(α-methylstyrene) as well of its copolymerization with styrene. These initiator systems also show that despite the I+ inductive effect of the methyl group, which enhances electron density at the vinyl double bond of styrene, the steric consequence of vinyl substitution hinders monomer coordination to active species, causing a decrease in conversion of either α-MeS to homopolymer or S/α-MeS to the corresponding copolymer. The nature and structure of the metallocene included in the initiator system are determinant of the initiator system’s efficiency. For the metallocenes used the efficiency follows the order IndTiCl 3 > Cp 2 TiCl 2 > (n-BuCp) 2 TiCl 2 , with the half-sandwich metallocene IndTiCl 3 showing greater efficiency than the true metallocenes.
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Styrene–substituted-styrene copolymerization using Diphenylzinc–metallocene–methylaluminoxane systems
Polymer International, 2020Co-Authors: Franco M Rabagliati, Francisco J. Rodríguez, Abdel Alla, Sebastián Muñoz-guerraAbstract:Homopolymerization of disubstituted styrenes (2,4- and 2,5-dimethylstyrene) and trisubstituted styrene (2,4,6-trimethylstyrene) and their copolymerization with styrene were carried out using Diphenylzinc–metallocene–methylaluminoxane initiator systems for metallocene (n-BuCp)2TiCl2 and for half-metallocene CpTiCl3. The studied comonomers were found to be less reactive than p-tertbutylstyrene, p-methylstyrene and styrene. The results indicate that, even though the methyl group has I+ inductive effect, di- and tri-methylstyrenes are reluctant to undergo either homopolymerization or copolymerization. This behavior suggests that the reactivity is regulated not only by the inductive effect of the alkyl group but also by the steric impediment caused by the crowding of the substituents on the benzene ring. Copyright © 2006 Society of Chemical Industry
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HOMO- AND COPOLYMERIZATION OF STYRENE AND STYRENE RELATED MONOMERS. SYNTHESIS AND CHARACTERIZATION
Journal of The Chilean Chemical Society, 2016Co-Authors: Franco M Rabagliati, Rodrigo A. Cancino, Francisco J. Rodríguez, Monica A Perez, Héctor E. Muñoz, Maria V. Cuevas, G. A. Mardones, Marcela Saavedra, M. Vidal, Lisa MuñozAbstract:Systems including Diphenylzinc, metallocene, and methylaluminoxane, at various combinations has been attempted, as initiating systems for homo- and copolymerization of styrene and various styrene related comonomers including : substituted styrenes, styrene derivatives, α-olefins, dienes and more recently cycohexenes including norbornene. The used metallocenes were those containing titanium, zirconium and for comparatives reasons hafnium. The metallocene efficiency towards syndiotactic polystyrene polymerization showed the order : titanocene > zirconocene > hafnocene. While the polymerization as well the copolymerization of Styrene with related to styrene compounds resulted to be much influenced by both electrical and steric hindrance effect. For styrene substituted derivative those group or element having I+ inductive effect depending its position at styrene’s its phenyl ring favours homopolymerization as well their copolymerization with styrene. The steric hindrance also showed a determinant influence on reactivity, so methyl and tert-butyl group, having a I+ effect, when at para -position improve activity and stereoregularity of their polymerization processes. But when placing at orto- position showed a very low capacity to polymerize. The present and previous results indicate that polymerization processes are initiated by monomer coordination to active metal species either of the binary metallocene-MAO or of the ternary Ph2Zn-metallocene-MAO.
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styrene substituted styrene copolymerization using Diphenylzinc metallocene methylaluminoxane systems
Polymer International, 2006Co-Authors: Franco M Rabagliati, Francisco J. Rodríguez, Abdel Alla, Sebastian MunozguerraAbstract:Homopolymerization of disubstituted styrenes (2,4- and 2,5-dimethylstyrene) and trisubstituted styrene (2,4,6-trimethylstyrene) and their copolymerization with styrene were carried out using Diphenylzinc–metallocene–methylaluminoxane initiator systems for metallocene (n-BuCp)2TiCl2 and for half-metallocene CpTiCl3. The studied comonomers were found to be less reactive than p-tertbutylstyrene, p-methylstyrene and styrene. The results indicate that, even though the methyl group has I+ inductive effect, di- and tri-methylstyrenes are reluctant to undergo either homopolymerization or copolymerization. This behavior suggests that the reactivity is regulated not only by the inductive effect of the alkyl group but also by the steric impediment caused by the crowding of the substituents on the benzene ring. Copyright © 2006 Society of Chemical Industry
Jesus Contreras - One of the best experts on this subject based on the ideXlab platform.
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Ring‐opening copolymerization of L‐lactide with ε‐caprolactone initiated by Diphenylzinc
Polymer International, 2020Co-Authors: Jesus Contreras, Darymar DavilaAbstract:Copolymerization of mixtures of L-lactide and e-caprolactone has been initiated by Diphenylzinc. The reaction conditions were investigated, to discover the effects on yield, molecular weight and microstructure of copolymers obtained. The temperature used varied between 50 and 120 °C, the molar ratio of monomer to initiator ranged between 90 and 1440 mol/mol, and the molar ratio of e-caprolactone to L-lactide employed was between 100/0 and 0/100 mol/mol. Copolymers were characterized by 1H-NMR, 13C-NMR, DSC and gel permeation chromatography. The results indicate that incorporation of L-lactide to the growing chain is preferred and e-caprolactone is copolymerized after most of the L-lactide has been depleted. The microstructure of obtained copolyesters was affected considerably by transesterification reactions. It was observed that increasing reaction temperature, reaction time and concentration initiator was advantageous to the transesterification. The crystallinity of copolyester obtained was determined by differential scanning calorimetry. The results are in good agreement with both molar composition and sequence distribution of copolyesters. Copyright © 2006 Society of Chemical Industry
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Ring-opening polymerization of ε-caprolactone initiated by Diphenylzinc
European Polymer Journal, 2020Co-Authors: M Vivas, Jesus ContrerasAbstract:Abstract In the present work the polymerization of e -caprolactone ( e -CL) using Ph 2 Zn as initiator is reported. The effects of reaction temperature, molar ratio of monomer/initiator and reaction time on the yield and the molecular weight are investigated. The temperature is varied between 20 and 120 °C and the molar ratio of monomer to initiator between 200 and 800 mol/mol. The results indicate that the Ph 2 Zn induces the polymerization of e -CL to high conversion and produces polymer with high molecular weight at temperatures around 40–60 °C.
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Synthesis of ε-caprolactone-b-l-lactide block copolymers by mean sequential polymerization, using Diphenylzinc as initiator
Polymer Bulletin, 2014Co-Authors: Jesus Contreras, Francisco López-carrasquero, Jennifer Pestana, Carlos TorresAbstract:Block copolymers of ε-caprolactone (CL) and l -lactide ( l -LA) were synthesized by sequential polymerization using Diphenylzinc as initiator. The composition of the copolymers was adjusted changing the comonomers in ratio. Copolymers were characterized by ^1H-NMR, ^13C-NMR, DSC, and GPC. Results indicate that poly(ε-caprolactone)- b -poly( l -lactide) (PCL- b -PLA) block copolymers had a narrow molecular weight distribution and well-controlled sequences without random placement.
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synthesis of e caprolactone b l lactide block copolymers by mean sequential polymerization using Diphenylzinc as initiator
Polymer Bulletin, 2014Co-Authors: Jesus Contreras, Francisco Lopezcarrasquero, Jennifer Pestana, Carlos F TorresAbstract:Block copolymers of e-caprolactone (CL) and l-lactide (l-LA) were synthesized by sequential polymerization using Diphenylzinc as initiator. The composition of the copolymers was adjusted changing the comonomers in ratio. Copolymers were characterized by 1H-NMR, 13C-NMR, DSC, and GPC. Results indicate that poly(e-caprolactone)-b-poly(l-lactide) (PCL-b-PLA) block copolymers had a narrow molecular weight distribution and well-controlled sequences without random placement.
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Synthesis of ε-caprolactone-b-l-lactide block copolymers by mean sequential polymerization, using Diphenylzinc as initiator
Polymer Bulletin, 2014Co-Authors: Jesus Contreras, Francisco López-carrasquero, Jennifer Pestana, Carlos F TorresAbstract:Block copolymers of e-caprolactone (CL) and l-lactide (l-LA) were synthesized by sequential polymerization using Diphenylzinc as initiator. The composition of the copolymers was adjusted changing the comonomers in ratio. Copolymers were characterized by 1H-NMR, 13C-NMR, DSC, and GPC. Results indicate that poly(e-caprolactone)-b-poly(l-lactide) (PCL-b-PLA) block copolymers had a narrow molecular weight distribution and well-controlled sequences without random placement.
Monica A Perez - One of the best experts on this subject based on the ideXlab platform.
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HOMO- AND COPOLYMERIZATION OF STYRENE AND STYRENE RELATED MONOMERS. SYNTHESIS AND CHARACTERIZATION
Journal of The Chilean Chemical Society, 2016Co-Authors: Franco M Rabagliati, Rodrigo A. Cancino, Francisco J. Rodríguez, Monica A Perez, Héctor E. Muñoz, Maria V. Cuevas, G. A. Mardones, Marcela Saavedra, M. Vidal, Lisa MuñozAbstract:Systems including Diphenylzinc, metallocene, and methylaluminoxane, at various combinations has been attempted, as initiating systems for homo- and copolymerization of styrene and various styrene related comonomers including : substituted styrenes, styrene derivatives, α-olefins, dienes and more recently cycohexenes including norbornene. The used metallocenes were those containing titanium, zirconium and for comparatives reasons hafnium. The metallocene efficiency towards syndiotactic polystyrene polymerization showed the order : titanocene > zirconocene > hafnocene. While the polymerization as well the copolymerization of Styrene with related to styrene compounds resulted to be much influenced by both electrical and steric hindrance effect. For styrene substituted derivative those group or element having I+ inductive effect depending its position at styrene’s its phenyl ring favours homopolymerization as well their copolymerization with styrene. The steric hindrance also showed a determinant influence on reactivity, so methyl and tert-butyl group, having a I+ effect, when at para -position improve activity and stereoregularity of their polymerization processes. But when placing at orto- position showed a very low capacity to polymerize. The present and previous results indicate that polymerization processes are initiated by monomer coordination to active metal species either of the binary metallocene-MAO or of the ternary Ph2Zn-metallocene-MAO.
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further studies on styrene styrene derivative copolymerizations using combined Diphenylzinc additive initiator systems
Polymer International, 2005Co-Authors: Franco M Rabagliati, Francisco J. Rodríguez, Monica A Perez, Carlos J Caro, Nicolas CrispelAbstract:A combination of Diphenylzinc, a metallocene and methylaluminoxane (Ph2Zn-metallocene-MAO) is a suitable initiator system for the polymerization of styrene and for its copolymerization with para-alkyl substituted styrenes. This paper reports new experimental results which reinforce our previous findings indicating that polymerization processes are initiated by monomer coordination to active species resulting from these particular combined systems. Polymerization propagates by a cationic pathway. Further to our previous observation that the I+ inductive effect of para-substituents in styrene improves conversion to polymer, we now find that methyl substitution on the vinyl double bond of styrene, in spite of the I+ inductive effect and as a result of increased steric hindrance, makes the polymerization process difficult. On the other hand, the replacement of titanocenes by zirconocenes or hafnocenes generates Ph2Zn-metallocene-MAO initiator systems which are also able to induce homo- and copolymerization, but with lower yields and producing practically amorphous polymers. The efficiency of our Ph2Zn-metallocene-MAO initiator systems follows the order titanocene > zirconocene > hafnocene, at least for the studied metallocenes. Copyright © 2004 Society of Chemical Industry
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Further studies on styrene/styrene derivative copolymerizations using combined Diphenylzinc-additive initiator systems †
Polymer International, 2004Co-Authors: Franco M Rabagliati, Francisco J. Rodríguez, Monica A Perez, Carlos J Caro, Nicolas CrispelAbstract:A combination of Diphenylzinc, a metallocene and methylaluminoxane (Ph2Zn-metallocene-MAO) is a suitable initiator system for the polymerization of styrene and for its copolymerization with para-alkyl substituted styrenes. This paper reports new experimental results which reinforce our previous findings indicating that polymerization processes are initiated by monomer coordination to active species resulting from these particular combined systems. Polymerization propagates by a cationic pathway. Further to our previous observation that the I+ inductive effect of para-substituents in styrene improves conversion to polymer, we now find that methyl substitution on the vinyl double bond of styrene, in spite of the I+ inductive effect and as a result of increased steric hindrance, makes the polymerization process difficult. On the other hand, the replacement of titanocenes by zirconocenes or hafnocenes generates Ph2Zn-metallocene-MAO initiator systems which are also able to induce homo- and copolymerization, but with lower yields and producing practically amorphous polymers. The efficiency of our Ph2Zn-metallocene-MAO initiator systems follows the order titanocene > zirconocene > hafnocene, at least for the studied metallocenes. Copyright © 2004 Society of Chemical Industry
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styrene styrene derivative and styrene 1 alkene copolymerization using ph2zn additive initiator systems
Macromolecular Symposia, 2004Co-Authors: Franco M Rabagliati, Rodrigo A. Cancino, Monica A Perez, Francisco J. RodríguezAbstract:Diphenylzinc-metallocene-MAO initiator systems have proven to be effective initiator systems for styrene and for substituted styrenes as well as for their styrene/(styrene-derivative) copolymerization. Titanocene produced almost pure syndiotactic polymers while zirconocenes gave atactic polystyrene together with a low content, less than 20%, of syndiotactic polystyrene. Systems including a zirconocene, particularly ethenyl(bisindenyl)zirconium dichloride were effective initiators of 1-alkene polymerization and of styrene/1-alkene copolymerization. Conversion to polymer increases with the molecular size of 1-alkene. Styrene derivative and styrene/(styrene derivative) polymerization was greatly influenced by the inductive effect of substituent and by steric hindrance due to the monomer.
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Styrene/(Styrene Derivative) and Styrene/(1‐Alkene) Copolymerization using Ph2Zn‐Additive Initiator Systems
Macromolecular Symposia, 2004Co-Authors: Franco M Rabagliati, Rodrigo A. Cancino, Monica A Perez, Francisco J. RodríguezAbstract:Diphenylzinc-metallocene-MAO initiator systems have proven to be effective initiator systems for styrene and for substituted styrenes as well as for their styrene/(styrene-derivative) copolymerization. Titanocene produced almost pure syndiotactic polymers while zirconocenes gave atactic polystyrene together with a low content, less than 20%, of syndiotactic polystyrene. Systems including a zirconocene, particularly ethenyl(bisindenyl)zirconium dichloride were effective initiators of 1-alkene polymerization and of styrene/1-alkene copolymerization. Conversion to polymer increases with the molecular size of 1-alkene. Styrene derivative and styrene/(styrene derivative) polymerization was greatly influenced by the inductive effect of substituent and by steric hindrance due to the monomer.
Francisco J. Rodríguez - One of the best experts on this subject based on the ideXlab platform.
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Styrene–substituted-styrene copolymerization using Diphenylzinc–metallocene–methylaluminoxane systems
Polymer International, 2020Co-Authors: Franco M Rabagliati, Francisco J. Rodríguez, Abdel Alla, Sebastián Muñoz-guerraAbstract:Homopolymerization of disubstituted styrenes (2,4- and 2,5-dimethylstyrene) and trisubstituted styrene (2,4,6-trimethylstyrene) and their copolymerization with styrene were carried out using Diphenylzinc–metallocene–methylaluminoxane initiator systems for metallocene (n-BuCp)2TiCl2 and for half-metallocene CpTiCl3. The studied comonomers were found to be less reactive than p-tertbutylstyrene, p-methylstyrene and styrene. The results indicate that, even though the methyl group has I+ inductive effect, di- and tri-methylstyrenes are reluctant to undergo either homopolymerization or copolymerization. This behavior suggests that the reactivity is regulated not only by the inductive effect of the alkyl group but also by the steric impediment caused by the crowding of the substituents on the benzene ring. Copyright © 2006 Society of Chemical Industry
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Styrene/substituted styrene copolymerization by Ph2Zn-metallocene-MAO systems : homo-and copolymerization of p-methoxystyrene with styrene
Polymer International, 2020Co-Authors: Franco M Rabagliati, Héctor E. Muñoz, Gabriela V. Mardones, Francisco J. RodríguezAbstract:BACKGROUND: The present work is part of a general study regarding the homo- and copolymerization of styrene using Diphenylzinc–additive initiator systems, with the aim of improving the properties of commercial atactic polystyrene. The study is focused on syndiotactic polystyrene and/or copolymers of styrene (S) with substituted styrene, styrene derivatives or various α-olefins. This research has been ongoing over the last 15 years. RESULTS: The reported experiments show that binary metallocene–methylaluminoxane (MAO) and ternary Ph2Zn–metallocene–MAO, depending on the metallocene employed, are capable of inducing both homo- and copolymerization of styrene and p-methoxystyrene (p-MeOS). The results indicate that for a styrene/p-MeOS mole ratio with p-MeOS > 25% the product obtained has only a minor incorporation of styrene units. The efficiency of the metallocenes studied follows the order bis(n-butylcyclopentadienyl)titanium dichloride ((n-BuCp)2TiCl2) > indenyltitanium trichloride (IndTiCl3) > Cp2TiCl2. CONCLUSION: Metallocenes (n-BuCp)2TiCl2, Cp2TiCl2 and IndTiCl3 in binary systems combined with MAO, as well as in ternary systems combined with Ph2Zn and MAO, induce the homopolymerization of p-MeOS and its copolymerization with styrene. The styrene/p-MeOS copolymer obtained was enriched in p-MeOS with respect to the initial feed, in agreement with the I+ inductive effect of the methoxy group in the para position of styrene. As already reported, the role of Ph2Zn was nullified by its complexation with the p-MeOS comonomer. Copyright © 2008 Society of Chemical Industry
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HOMO- AND COPOLYMERIZATION OF STYRENE AND STYRENE RELATED MONOMERS. SYNTHESIS AND CHARACTERIZATION
Journal of The Chilean Chemical Society, 2016Co-Authors: Franco M Rabagliati, Rodrigo A. Cancino, Francisco J. Rodríguez, Monica A Perez, Héctor E. Muñoz, Maria V. Cuevas, G. A. Mardones, Marcela Saavedra, M. Vidal, Lisa MuñozAbstract:Systems including Diphenylzinc, metallocene, and methylaluminoxane, at various combinations has been attempted, as initiating systems for homo- and copolymerization of styrene and various styrene related comonomers including : substituted styrenes, styrene derivatives, α-olefins, dienes and more recently cycohexenes including norbornene. The used metallocenes were those containing titanium, zirconium and for comparatives reasons hafnium. The metallocene efficiency towards syndiotactic polystyrene polymerization showed the order : titanocene > zirconocene > hafnocene. While the polymerization as well the copolymerization of Styrene with related to styrene compounds resulted to be much influenced by both electrical and steric hindrance effect. For styrene substituted derivative those group or element having I+ inductive effect depending its position at styrene’s its phenyl ring favours homopolymerization as well their copolymerization with styrene. The steric hindrance also showed a determinant influence on reactivity, so methyl and tert-butyl group, having a I+ effect, when at para -position improve activity and stereoregularity of their polymerization processes. But when placing at orto- position showed a very low capacity to polymerize. The present and previous results indicate that polymerization processes are initiated by monomer coordination to active metal species either of the binary metallocene-MAO or of the ternary Ph2Zn-metallocene-MAO.
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styrene substituted styrene copolymerization using Diphenylzinc metallocene methylaluminoxane systems
Polymer International, 2006Co-Authors: Franco M Rabagliati, Francisco J. Rodríguez, Abdel Alla, Sebastian MunozguerraAbstract:Homopolymerization of disubstituted styrenes (2,4- and 2,5-dimethylstyrene) and trisubstituted styrene (2,4,6-trimethylstyrene) and their copolymerization with styrene were carried out using Diphenylzinc–metallocene–methylaluminoxane initiator systems for metallocene (n-BuCp)2TiCl2 and for half-metallocene CpTiCl3. The studied comonomers were found to be less reactive than p-tertbutylstyrene, p-methylstyrene and styrene. The results indicate that, even though the methyl group has I+ inductive effect, di- and tri-methylstyrenes are reluctant to undergo either homopolymerization or copolymerization. This behavior suggests that the reactivity is regulated not only by the inductive effect of the alkyl group but also by the steric impediment caused by the crowding of the substituents on the benzene ring. Copyright © 2006 Society of Chemical Industry
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further studies on styrene styrene derivative copolymerizations using combined Diphenylzinc additive initiator systems
Polymer International, 2005Co-Authors: Franco M Rabagliati, Francisco J. Rodríguez, Monica A Perez, Carlos J Caro, Nicolas CrispelAbstract:A combination of Diphenylzinc, a metallocene and methylaluminoxane (Ph2Zn-metallocene-MAO) is a suitable initiator system for the polymerization of styrene and for its copolymerization with para-alkyl substituted styrenes. This paper reports new experimental results which reinforce our previous findings indicating that polymerization processes are initiated by monomer coordination to active species resulting from these particular combined systems. Polymerization propagates by a cationic pathway. Further to our previous observation that the I+ inductive effect of para-substituents in styrene improves conversion to polymer, we now find that methyl substitution on the vinyl double bond of styrene, in spite of the I+ inductive effect and as a result of increased steric hindrance, makes the polymerization process difficult. On the other hand, the replacement of titanocenes by zirconocenes or hafnocenes generates Ph2Zn-metallocene-MAO initiator systems which are also able to induce homo- and copolymerization, but with lower yields and producing practically amorphous polymers. The efficiency of our Ph2Zn-metallocene-MAO initiator systems follows the order titanocene > zirconocene > hafnocene, at least for the studied metallocenes. Copyright © 2004 Society of Chemical Industry
Raul Quijada - One of the best experts on this subject based on the ideXlab platform.
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Polymerization and copolymerization of styrene by Ph2Zn-Metallocene-MAO initiator systems
Macromolecular Symposia, 2001Co-Authors: Franco M Rabagliati, Rodrigo A. Cancino, Francisco J. Rodríguez, Monica A Perez, H. A. Ayal, Marcelo A Soto, Carlos J Caro, A. León, Raul QuijadaAbstract:Combined systems including Diphenylzinc, Ph 2 Zn, a metallocene, and methylaluminoxane, MAO, have been employed to initiate styrene polymerization. These initiator systems have been also used to initiate the copolymerization of styrene with p-alkylsubstituted styrenes and with α-olefins. Both polymerization and copolymerization processes depend on the nature of the metallocene included in the initiator system, the presence of Ph 2 Zn, the temperature and the solvent used. Titanocenes produced syndiotactic polystyrene, s-PS, while zirconocenes gave atactic polystyrene, a-PS, with a certain content, less the 20% of s-PS. For copolymerizations the conversion to polymer was also influenced by the comonomer nature and its molar proportion in the initial feed, as well as the sort of metallocene, titanocene or zirconocene included.
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polymerization of styrene by Diphenylzinc additive systems part x homo and copolymerization of styrene using ph2zn metallocene mao systems
Boletin De La Sociedad Chilena De Quimica, 2000Co-Authors: Franco M Rabagliati, Rodrigo A. Cancino, Francisco J. Rodríguez, Monica A Perez, H. A. Ayal, Marcelo A Soto, A. León, Raul QuijadaAbstract:La combinacion de difenilcinc, Ph2Zn, ciclopentadienil titanium tricloruro, CpTiCl3, y metilaluminoxano, MAO, se usaron como iniciador de la polimerizacion de estireno, S, y de su copolimerizacion con 1-hexadeceno, 1-C16H32, y con p-ter-butilestireno, p-ButS. En la homopolimerizacion mediante Ph2Zn-CpTiCl3-MAO se obtuvo poliestireno sindiotactico, s-PS, casi puro, mientras que las otras combinaciones de estos componentes producen poliestireno atactico, a-PS, o no polimerizan al estireno. Los sistemas CpTiCl3-MAO y Ph2Zn-CpTiCl3-MAO resultaron ser iniciadores efectivos de la copolimerizacion de S/1-C16H32 y de S/ p-ButS. Los copolimeros S/1-C16H32 mostraron, senal de temperatura de fusion cristalina en el intervalo 235 - 255 °C, mientras que los copolimeros S/p-ButS no mostraron Tm, pero se comportan como polimeros estereoregulares
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polymerization of styrene by Diphenylzinc additive systems part ix new experiments with ph2zn met mao systems
Polymer International, 1999Co-Authors: Franco M Rabagliati, Rodrigo A. Cancino, Monica A Perez, Raul QuijadaAbstract:The combined systems Diphenylzinc-metallocene-methylaluminoxane (Ph 2 Zn-Met-MAO) have proved able to induce styrene polymerization, producing polystyrene with a variable content of stereoregular polymer. The tacticity of the obtained polymer is strongly dependent on the nature of the metallocene and on its molar ratio toward Diphenylzinc (Met/Ph 2 Zn). The stereoregular polymer was syndiotactic according to its crystalline melting temperature T m , 13 C NMR spectrum, and insolubility in boiling butanone.
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polymerization of styrene by Diphenylzinc additive systems part vii ph2zn n bucp 2ticl2 mao systemsa
Polymer Bulletin, 1998Co-Authors: Franco M Rabagliati, Monica A Perez, Raul QuijadaAbstract:The polymerization of styrene using the combined system Diphenylzinc-bis(n-butylcyclopentadienyl)titani dichloride-methylaluminoxane, Ph 2 Zn-(n-BuCp) 2 TiCl 2 -MAO, in toluene at 60°C, produced highly syndiotactic polystyrene, confirming that Ph 2 Zn-titanocene-MAO are good initiator systems for the stereoregular polymerization of styrene. The syndiotacticity of PS was established by its insolubility in chloroform, benzene or toluene, and after continuous extraction in boiling butanone. DSC analysis showed endotherm signals corresponding to the melting temperature, T m , of syndiotactic polystyrene.
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some studies on styrene polymerization using new systems prepared from coordination metal compounds rebr co 3 3 3 dimethyl 2 2 biquinoline Diphenylzinc with and without mao systems
Polymer Bulletin, 1998Co-Authors: C. A. Terraza, Franco M Rabagliati, S. A. Moya, Juan Guerrero, Raul QuijadaAbstract:The monovalent rhenium compounds ReBr(CO)3(3,3′-dimethyl-2,2′-biquinoline) (I) and ReBr(CO)5 (II) could be used as catalysts in styrene polymerization after activation with Diphenylzinc (Ph2Zn) and methylaluminoxane (MAO). The catalytic activity shown by the I-Ph2Zn-MAO system was dependent on the molar ratio between the components and the temperature of polymerization. Non stereoregular polystyrene (PS) was obtained under all experimental conditions. The resulting PS gave multimodal GPC traces suggesting the presence of different species capable of polymerizing styrene, possibly species resulting from MAO alone, I-Ph2Zn and I-Ph2Zn-MAO systems.