Polymerization of isobutylene and copolymerization of isobutylene with isoprene promoted by methylalumoxane

Lisovskii, Anatoly; Nelkenbaum, Elza; Volkis, Victoria; Semiat, Rafi; Eisen, Moris S.

doi:10.1016/s0020-1693(02)00799-5

Cited by 19 publications

(14 citation statements)

References 46 publications

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“…Despite the high M v values observed at low MAO concentrations ( M v = 61,000−190,000 g mol −1 ), all obtained polymers were colorless viscous sticky liquids, which indicates that relatively low‐molecular‐weight polymers were in fact formed. Unfortunately, any data about the number average molecular weight and polydispersity of synthesized PIBs are absent in this article 70. The chain end analysis of obtained PIBs by means of 1 H NMR and 13 C NMR spectroscopy revealed the tert ‐butyl head group and exo ‐olefin end group, respectively.…”

Section: Room Temperature Polymerization Of Ibmentioning

confidence: 90%

“…Indeed, relatively high‐molecular‐weight polymers ( M n from 2,000 and up to 60,000 g mol −1 ) were obtained using MAO as catalyst in the room temperature cationic polymerization of styrenes,67, 68 isobutyl vinyl ethers,67, 68 or cyclopentadiene 69. Unfortunately, only one work is related to the investigation the cationic polymerization of IB mediated by MAO 70. It was shown that MAO induced the cationic polymerization of IB at 25 °C in CH 2 Cl 2 (monomer/solvent ∼1:1 v/v) to afford polymers with viscosity‐average molecular weight ( M v ) between 8,000 and 190,000 g mol −1 depending on the MAO concentration.…”

Section: Room Temperature Polymerization Of Ibmentioning

confidence: 99%

“…It should be also noted that MAO showed good activity in the cationic polymerization of IB only in polar CH 2 Cl 2 , whereas only traces of polymer were formed in toluene. Finally, MAO also initiated the cationic copolymerization of IB with isoprene, although relatively low‐molecular‐weight copolymers in comparison with homopolymers of IB were obtained at ambient temperature ( M v = 4,000−12,000 g mol −1 at 0 °C) 70…”

Section: Room Temperature Polymerization Of Ibmentioning

confidence: 99%

“…69 Unfortunately, only one work is related to the investigation the cationic polymerization of IB mediated by MAO. 70 It was shown that MAO induced the cationic polymerization of IB at 25 C in CH 2 Cl 2 (monomer/solvent $1:1 v/v) to afford polymers with viscosity-average molecular weight (M v ) between 8,000 and 190,000 g mol À1 depending on the MAO concentration. Despite the high M v values observed at low MAO concentrations (M v ¼ 61,000À190,000 g mol À1 ), all obtained polymers were colorless viscous sticky liquids, which indicates that relatively low-molecular-weight polymers were in fact formed.…”

Section: Rzncl (R ¼ Et or Oct)-based Initiating Systemsmentioning

confidence: 99%

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Cationic polymerization of isobutylene at room temperature

Kostjuk¹,

Yeong²,

Voit³

2012

J. Polym. Sci. A Polym. Chem.

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This review highlights recent approaches toward polyisobutylene (PIB) by an energy efficient room temperature cationic polymerization. Special focus is laid on our own work using modified Lewis acids and nitrile-ligated metal complexes associated with weakly coordinating anions. In both cases, suitable conditions have been found for efficient production of PIB characterized by medium to low molar masses and a high content of exo double bonds as end groups-the typical features of highly reactive PIB, an important commercial intermediate toward oil and gasoline additives. These and other approaches demonstrate that the cationic polymerization of isobutylene is still not fully explored, and new innovative catalyst systems can lead to surprising results of high commercial interest.

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Section: Room Temperature Polymerization Of Ibmentioning

confidence: 90%

Section: Room Temperature Polymerization Of Ibmentioning

confidence: 99%

Section: Room Temperature Polymerization Of Ibmentioning

confidence: 99%

Section: Rzncl (R ¼ Et or Oct)-based Initiating Systemsmentioning

confidence: 99%

See 2 more Smart Citations

Cationic polymerization of isobutylene at room temperature

Kostjuk¹,

Yeong²,

Voit³

2012

J. Polym. Sci. A Polym. Chem.

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“…Recently, a number of reports have appeared on the use of alkylaluminoxane coinitiators for the synthesis of high-MW grades of IB polymers at elevated reaction temperatures. [47][48][49][50][51] Of these, the most promising is a system based on toluene solutions of methylaluminoxane (MAO) in conjunction with carbocation synthon initiators. 50 On review of the data presented, it became apparent that the utility of this system was severely limited in that polymerization must be conducted below −33°C in hydrocarbon media, the coinitiator becomes entrained in the product and useful initiators were restricted to carbocation synthons.…”

Section: Introductionmentioning

confidence: 99%

Greener, cleaner polymerization of isobutene

Liu¹,

Mathers²,

Damodaran³

et al. 2013

Green Materials

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Methylaluminoxane (MAO)/silyl halide-based initiator systems greatly improve the sustainability of isobutene (IB)polymerizations by eliminating halogenated solvents, reducing energy consumption and removing the need for postpolymerization purifi cation. These solvent-free systems give rise to moderate yields of high-molecular-weight (MW) polymers at convenient temperatures without conventional toxic solvents. In addition, facile separation of MAO and polyisobutene (PIB) was accomplished with supported MAOs. The resulting system gave enhanced activity and high yields of medium-to-high-MW polymer at temperatures up to ambient. The MW-temperature profi le for MAO-based systems approximates that for γ-radiation and perfl uoroarylated Lewis acid-based systems; however, the former does not require high-purity monomer and is more economical and easily scalable. Modeling experiments involving 2,4,4-trimethyl-1-pentene indicate that silyl halides undergo ligand-exchange type reactions with MAO where halogen attached to silicon is replaced with a methyl substituent from MAO with concomitant production of chloraluminoxane and initiation of cationic polymerization in an ill-defi ned manner. IntroductionCationic polymerization 1-3 is a useful technique for the synthesis of a number of important materials including terpenic resins 4 and isobutene (IB)-based polymers. 5 From the standpoint of green chemistry, 6 this methodology has a number of inherent limitations that have proven diffi cult to surmount. Historically, the inverse relationship between polymer molecular weight (MW) and temperature (T) has necessitated energy intensive cooling for the synthesis of high-MW products. 7,8 Another challenge is that the Lewis acid (LA) coinitiators commonly used as a component of the initiator system remain trapped inside the product mixture. This combined with the hydrolytic instability of most LAs 9-11 precludes recycling of the coinitiator, adds post-polymerization purifi cation steps (requiring a larger plant footprint) and generates waste. Finally, given the ionic nature of the species involved in cationic polymerization, most systems only operate effi ciently in polar solvents, which are often halogenated (e.g. methyl chloride) and ultimately toxic and detrimental to the environment. 12Although numerous advances have been made over the years in improving the MW-T profi le for IB polymerizations, the majority of these systems require expensive initiator systems, solvents/monomers of ultrahigh purity and temperatures below −20°C. 13-46 Thus, a longstanding goal has been the development of initiator systems capable of producing high-MW polymers at temperatures closer to ambient in neat monomer or aliphatic solvents of moderate purity, while using a low cost and/or recyclable LA coinitiator that does not contaminate the product. Recently, a number of reports have appeared on the use of alkylaluminoxane coinitiators for the synthesis of high-MW grades of IB polymers at elevated reaction temperatures. 47-51 Of these, the most promising...

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Butyl Rubber

Webb¹,

Shaffer²,

Tsou³

2003

Kirk-Othmer Encyclopedia of Chemical Technology

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Butyl rubber and other isobutylene polymers in wide use include various homopolymers and copolymers. Low levels of unsaturation for subsequent cross‐linking are incorporated by copolymerization with isoprene. Halogenation at the unsaturation site provides additional cross‐linking mechanisms and covulcanization with highly unsaturated elastomers. Polymers containing star branches, conjugated‐diene sites, divinylbenzene, and brominated p ‐methylstyrene have also been synthesized. Isobutylene polymers are polymerized by a cationic mechanism, using a Brønsted acid as an initiator and a Lewis acid as a coinitiator, eg, water and aluminum chloride. Molecular weights range from several hundred for terminally unsaturated polybutenes to over a million for elastomer grades. The T g of polyisobutylene is about −70°C, and the polymer is amorphous in the unstrained state. The polymers exhibit a broad damping peak and a low plateau modulus. They display an exceptionally low permeability to gases, and are widely used as air retention barriers in tires. Optimum physical properties are obtained by compounding with carbon black and other fillers. Various mechanisms are used to cross‐link the compounds into elastomeric vulcanizates. Sulfur is used to provide polysulfidic cross‐links, while resin and zinc oxide cure systems give carbon–carbon cross‐links. Besides inner tubes and innerliners, butyl rubbers are used in blends to improve cut‐growth resistance and wet‐skid resistance. Blends with thermoplastic resins improve toughness. Polyisobutylenes enjoy extensive use as adhesives and caulks, and are chemically modified for use in lubricants as dispersants.

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Polymerization of isobutylene and copolymerization of isobutylene with isoprene promoted by methylalumoxane

Cited by 19 publications

References 46 publications

Cationic polymerization of isobutylene at room temperature

Cationic polymerization of isobutylene at room temperature

Greener, cleaner polymerization of isobutene

Butyl Rubber

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