Some effects of the initiator on the cationic polymerization of alkenes

Plesch, P. H.; Austin, James C.

doi:10.1002/pola.22667

Cited by 5 publications

(2 citation statements)

References 40 publications

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“…Another explanation, again in polar media (ϵ ≫ 4), is that primarily unpaired cations propagate at low T , while ion-pairs dominate the kinetics at higher T so that the T dependence of MW should show a “kink” because of the T dependence of the equilibrium constant governing the concentration of these two species. This theory predicts that polymerizations in apolar media such as hexane (ϵ = 2.2) should not show this phenomenon as the kinetics are dominated by ion-pairs at all accessible temperatures …”

Section: Resultsmentioning

confidence: 99%

Isobutene Polymerization Using Chelating Diboranes: Polymerization in Aqueous Suspension and Hydrocarbon Solution

Lewis¹,

Chai²,

Collins³

et al. 2008

Organometallics

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The use of the chelating diboranes o-C6F4[B(C6F5)2]2 (1) and o-C6F4(9-BC12F8)2 (2: 9-BC12F8 = 1,2,3,4,5,6,7,8-octafluoro-9-borafluorene) for the polymerization of isobutene (IB) in aqueous suspension or in hydrocarbon solution was studied. Polymerizations in aqueous suspension provided polymer of moderate MW and at variable conversion and were dependent on temperature, mode of diborane addition, the presence of surfactant, and the acidity of and nature of the anion present in the aqueous phase. The T dependence of MW over the T range −80 to −20 °C was studied in aqueous suspension, and higher MW polymer was formed at lower T. The hydrolysis and methanolysis of diboranes 1 and 2 was studied by NMR spectroscopy. Reactions of diborane 1 with excess MeOH or water afford solutions containing oxonium acids [o-C6F4{B(C6F5)2}2(μ-OR)][(ROH) n H] (7: R = H, n > 2; 3: R = Me, n = 3). When diborane 1 is present in excess over water or MeOH, degradation of the diborane is observed. In this case the products are o-C6F4{B(C6F5)2}H (5) and (C6F5)2BOH 7 or (C6F5)2BOMe 4, respectively. In the case of diborole 2, o-C6F4(9-BC12F8)B(2-C12F8-2′′-H)(μ-OH)·7H2O (17) and o-C6F4(9-BC12F8)B(2-C12F8-2′′-H)(μ-OMe) (11) were isolated from reactions of 2 with water and MeOH, respectively, and were characterized by X-ray crystallography. None of these degradation products effect IB polymerization in aqueous suspension. As a model for initiation of polymerization, the reaction of diborole 2 with 1,1-diphenylethylene (DPE) was studied. Addition of MeOH at low T results in efficient formation of the ion-pair [Ph2CMe][o-C6F4(9-BC12F8)2(μ-OMe)] via protonation of DPE. Polymerizations in hydrocarbon media were exothermic and rapid and gave quantitative yields of polymer even at very low concentrations of diborane 1. The T dependence of MW was studied in hydrocarbon solution and showed non-Arrhenius behavior. This was explained by competitive chain transfer to monomer at elevated T and chain transfer to molecular water at lower T.

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Section: Resultsmentioning

confidence: 99%

Isobutene Polymerization Using Chelating Diboranes: Polymerization in Aqueous Suspension and Hydrocarbon Solution

Lewis¹,

Chai²,

Collins³

et al. 2008

Organometallics

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“…It has been thoroughly demonstrated that the reactivity of a carbocation generated from a polymerization system is highly dependent on multiple variables including chemical composition of the initiator (i.e. the cationogen), Lewis acid coinitiator, monomer, and solvent . Due to the strong stabilizing effect of the oxygen atom next to the vinyl group, the activation energy associated with the addition of a vinyl ether monomer to a given carbocation is relatively low compared to that of other alkene monomers .…”

Section: Homopolymerization and Homopolymer Propertiesmentioning

confidence: 99%

2‐(Vinyloxy)ethyl soyate as a versatile platform chemical for coatings: An overview

Alam

Kalita

Jayasooriya

et al. 2013

Euro J Lipid Sci & Tech

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A plant oil-based polymer technology was recently developed that enables high molecular weight polyvinylether polymers to be produced using cationic polymerization. The plant oil monomer synthesis involves simple base-catalyzed transesterification of a plant oil triglyceride with a hydroxy-functional vinyl, ether such as 4-(vinyloxy)butanol or 2-(vinyloxy)ethanol, to produce a mixture of vinyl ether monomers that possess fatty acid ester groups in their structure. A key aspect of the technology involves the polymerization process that allows for high molecular weight polymers to be produced by polymerization exclusively through the vinyl ether double bonds. This feature enables polymers to be produced that possess unsaturation in the fatty acid ester pendent groups derived from the plant oil starting material. As has been done for conventional plant oil triglycerides, the double bonds can be used to produce thermoset materials either directly through an oxidative process or by derivatization to produce other functional groups, such as epoxides, acrylates, and hydroxyls that can be subsequently used to produce crosslinked networks. The polymerization process also results in a "living" polymerization that allows for control of polymer molecular weight, narrow molecular weight distributions, and the production of unique polymer architectures such as block copolymers. Another very important feature of the technology involves the ability to copolymerize the plant oil-based vinyl ether monomers with other monomers to tailor polymer properties such as glass transition temperature, mechanical properties, and solubility/compatibility with other materials. This document provides an overview of the present state of the technology using soybean oil as a representative plant oil source.

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Research on the Development Trend of Online Education Industry Considering the Influence of Big Data and Artificial Intelligence

2019

Advances in Intelligent Systems and Computing

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Some effects of the initiator on the cationic polymerization of alkenes

Cited by 5 publications

References 40 publications

Isobutene Polymerization Using Chelating Diboranes: Polymerization in Aqueous Suspension and Hydrocarbon Solution

Isobutene Polymerization Using Chelating Diboranes: Polymerization in Aqueous Suspension and Hydrocarbon Solution

2‐(Vinyloxy)ethyl soyate as a versatile platform chemical for coatings: An overview

Research on the Development Trend of Online Education Industry Considering the Influence of Big Data and Artificial Intelligence

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