Cationic Polymerizations

Prez, Filip Du; Goethals, Eric J.; Hoogenboom, Richard

doi:10.1002/9781118480793.ch8

Cited by 4 publications

(9 citation statements)

References 178 publications

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“…In analogy to the free radical polymerization like reaction that is proposed for the formation of EME below the ionization threshold, this alternative mechanism would correspond to a cationic polymerization (Scheme ). However, we do not find any specific side products that would result from such a reaction between CH 3 O + and C 2 H 4 that are not also formed upon irradiation of pure CH 3 OH or pure C 2 H 4 above their ionization energies and thus can give direct support for this hypothesis.…”

Section: Resultsmentioning

confidence: 48%

Electron-Induced Formation of Ethyl Methyl Ether in Condensed Mixtures of Methanol and Ethylene

2018

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Electron-induced reactions in condensed mixtures of ethylene (C2H4) and methanol (CH3OH) lead to the formation of ethyl methyl ether (EME, C2H5OCH3), as shown by post-irradiation thermal desorption spectrometry (TDS). In contrast to the electron-induced reaction between water (H2O) and C2H4, product formation as a consequence of proton transfer following electron attachment (EA) to C2H4 is not observed in the analogous reaction between CH3OH and C2H4. However, a resonant process centered around 5.5 eV and a threshold-type increase of product yield starting at 9 eV is observed. On the basis of the presence and absence of particular side products after irradiation of the mixture as well as of the pure parent compounds, reaction mechanisms related to the two energy regimes are proposed. Below the ionization threshold of the reactants, dissociative electron attachment (DEA) to CH3OH triggers the reaction sequence by producing reactive methoxy radicals, which attack neighboring C2H4 molecules. The resulting adduct then abstracts a hydrogen atom to yield EME. Above but near the ionization threshold, electron impact ionization (EI) produces primarily intact molecular cations, which drive the reaction by converting the repulsive Coulomb force between the high electron densities at the reactive sites of the two neutral parent species into an attractive force. This again induces the formation of an adduct between the two reactants that rearranges to the product EME. Fragmentation of the molecular CH3OH+• cation into CH3O+, however, may provide an additional reaction pathway toward EME. In this scenario, CH3O+ attacks a neighboring C2H4 molecule. The resulting adduct is then neutralized by a thermalized electron and abstracts a hydrogen atom from a nearby CH3OH molecule to yield EME.

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Section: Resultsmentioning

confidence: 48%

Electron-Induced Formation of Ethyl Methyl Ether in Condensed Mixtures of Methanol and Ethylene

2018

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“…A third system employing a “non‐controlled” cationic polymerization was applied, which is known to produce high‐molecular‐weight PIB (hmPIB) with

{\overset{M}{true}}_{normaln}

> 10 5 g mol −1 . Using H 2 O/1,2‐dimethoxybenzene/AlCl 3 as the initiator system, hmPIB was first isolated under homogeneous conditions (entry 11,

{\overset{M}{true}}_{normaln}

= 162 000 g mol −1 , PDI = 3.7).…”

Section: Resultsmentioning

confidence: 99%

“…[ 17 ] A third system employing a "non-controlled" cationic polymerization was applied, which is known to produce high-molecular-weight PIB (hmPIB) with M n > 10 5 g mol −1 . [ 27 ] Using H 2 O/1,2-dimethoxybenzene/AlCl 3 as the initiator system, [ 16 ] hmPIB was fi rst isolated under homogeneous conditions (entry 11, M n = 162 000 g mol −1 , PDI = 3.7). In this instance, 67 vol% instead of 40 vol% n -hexane was necessary to prevent precipitation of the polymer.…”

Section: Emulsion Polymerization Of Ibmentioning

confidence: 99%

Poly(isobutylene) Nanoparticles via Cationic Polymerization in Nonaqueous Emulsions

Schuster

Golling

Krumpfer

et al. 2014

Macromol. Rapid Commun.

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The preparation of poly(isobutylene) (PIB) nanoparticles via cationic emulsion polymerization is presented. As a requirement, an oil-in-perfluoroalkane nonaqueous emulsion is developed, which is inert under the carbocationic polymerization conditions. To stabilize the dichloromethane/hexane droplets in the fluorinated, continuous phase, an amphiphilic block copolymer emulsifier is prepared containing PIB and 1H,1H-perfluoroalkylated poly(pentafluorostyrene) blocks. This system allows for the polymerization of isobutylene with number-average molecular weights (Mn) up to 27,000 g mol(-1). The particle morphologies are characterized via dynamic light scattering and electron microscopy. For Mn > 20,000 g mol(-1), the particles exhibit shape-persistence at room temperature and are ≈100 nm in diameter.

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“…A particularly useful aspect of oxazoline rings is that they are electron‐rich and quite stable, but once catalyzed, they can rapidly polymerize. As a result and combined with their aromatic structure, therefore hold the promise as latent yet rapid curing resins able to form high‐performance polymer networks when in the form of bisoxazoline monomers 5,13 . Indeed, oxazolines are known to polymerize via a cationic ring‐opening mechanism as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…As a result and combined with their aromatic structure, therefore hold the promise as latent yet rapid curing resins able to form high-performance polymer networks when in the form of bisoxazoline monomers. 5,13 Indeed, oxazolines are known to polymerize via a cationic ring-opening mechanism as shown in Figure 1. In the example given, reaction is initiated via quaternization of the imino nitrogen via methyl transfer from methyl triflate (MT) effectively giving it a positive charge.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and cure kinetics of bisoxazoline monomers during cationic ring‐opening polymerization

Issazadeh,

Khan,

Gan

et al. 2023

J of Applied Polymer Sci

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In this work, the synthesis and characterization of highly aromatic bisoxazoline (BOX) monomers containing diphenyl ether, furan, and thiophene backbones are presented. Preliminary investigations of the cure and reaction kinetics are performed to understand the impact of these moieties on polymerization and their glass transition temperatures. To do this, two catalysts are used, methyl triflate (MT) and dodecyl benzene sulfonic acid (DBS) to explore their role in controlling the cationic ring‐opening polymerization (CROP) mechanism. Polymerization was monitored using non‐isothermal differential scanning calorimetry and characterized according to the Kissinger and Ozawa models. Kinetic modeling using the Malek and Sestak‐Berggren methods showed excellent agreement with experimental values and was used to determine reaction rate constants. The polymerization of BOX monomers in the presence of both MT and DBS is shown to be highly latent, being stable until the melting point is reached, after which reaction occurs rapidly.

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Cationic Polymerizations

Cited by 4 publications

References 178 publications

Electron-Induced Formation of Ethyl Methyl Ether in Condensed Mixtures of Methanol and Ethylene

Electron-Induced Formation of Ethyl Methyl Ether in Condensed Mixtures of Methanol and Ethylene

Poly(isobutylene) Nanoparticles via Cationic Polymerization in Nonaqueous Emulsions

Synthesis and cure kinetics of bisoxazoline monomers during cationic ring‐opening polymerization

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