Microwave Accelerated Polymerization of 2‐Phenyl‐2‐oxazoline: Microwave or Temperature Effects?

Hoogenboom, Richard; Leenen, Mam Mark; Wiesbrock, Frank; Schubert, Ulrich S.

doi:10.1002/marc.200500370

Cited by 37 publications

(28 citation statements)

References 25 publications

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“…[141,142] These observations were attributed to effective interaction of the cationic charged propagating polymer chain with the dielectric heating by microwaves, resulting in selective excitation of the reaction center. Schubert and coworkers found identical polymerization rates for the polymerization of 2-phenyl-2-oxazoline in butyronitrile in a single-mode microwave reactor as well as under CH, [143] which were found to be in perfect agreement with the polymerization rate reported by Ritter and coworkers for the microwaveassisted protocol. [141,142] The influence of solvent mixtures with different ratios of dichloromethane and acetonitrile on the polymerization rate of 2-nonyl-2-oxazoline in a single-mode microwave reactor was investigated by Schubert and coworkers.…”

Section: Cyclic Imino Etherssupporting

confidence: 76%

One Decade of Microwave‐Assisted Polymerizations: Quo vadis?

Ebner

Bodner

Stelzer

et al. 2011

Macromol. Rapid Commun.

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The application of microwave irradiation in polymer syntheses and modifications is of continuously growing interest and has received significant international interest since the beginning of the millennium. Preceded by a review that was published 6 years ago, the present paper summarizes the most recent trends in this research area. Radical as well as step-growth and ring-opening polymerizations will be addressed; furthermore, the evolution from microwave-assisted polymerizations to microwave-assisted material fabrication will be described on the examples of polymeranalogous reactions, polymer/metal composites and bio-based materials.

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Section: Cyclic Imino Etherssupporting

confidence: 76%

One Decade of Microwave‐Assisted Polymerizations: Quo vadis?

Ebner

Bodner

Stelzer

et al. 2011

Macromol. Rapid Commun.

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“…[36] Nonetheless, no effects as a result of specific microwave absorption for the polymerization of PhOx under both microwave heating and thermal heating were observed in our laboratories. [34,37] Even though the underlying principle of the acceleration of the polymerization of 2-oxazolines under microwave irradiation is still under debate, the resulting fast and clean microwaveassisted polymerization procedure is very well suited for the synthesis of libraries of well defined (co)polymers. For this purpose an automated microwave synthesizer has been included in our high-throughput workflow ( Figure 3) to allow fast and reliable synthesis and characterization of libraries of well-defined (co)poly(2-oxazoline)s. [38] Structure-Property Relationships of Poly(2-oxazoline)s…”

Section: Optimization Of the Cationic Ring-opening Polymerization Of mentioning

confidence: 99%

Poly(2‐oxazoline)s: Alive and Kicking

Hoogenboom

2007

Macro Chemistry & Physics

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The development of various living/controlled polymerization techniques has allowed the synthesis of a large variety of well‐defined (co)polymers with varied polymer length, composition, and architecture, for example. Screening this large possible parameter space for a polymer with certain properties can be a very demanding process. Therefore, we aim to rapidly synthesize and systematically screen libraries of copolymers to determine structure‐property relationships that might allow the future design of novel (co)polymers with predictable properties. The cationic ring‐opening polymerization of 2‐oxazolines has been adapted for the synthesis of libraries of well‐defined (co)polymers. In this contribution, the optimization of the polymerization procedure using both high‐throughput experimentation and microwave irradiation is discussed. Subsequently, the microwave‐assisted synthesis of well‐defined libraries of (co)poly(2‐oxazoline)s and the determination of structure‐property relationships for these polymers is described. Moreover, the polymerization of a soy‐based 2‐oxazoline monomer will be illustrated as a ‘green’ approach to replace current oil‐based feedstock by renewable resources.magnified image

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“…[10][11][12] Very recently, Schubert et al demonstrated that the cationic ROP of 2-oxazoline and its derivatives was accelerated under a superheated condition by conventional heating, although a similar acceleration induced by microwave heating (MH) had previously been observed. [12][13][14][15] Similarly, we revealed that the enhancement of flash conventional heating (FCH) on the ROP of e-CL with Sn(Oct) 2 as a catalyst, matched well that seen with MH. [16] It seems that the thermal condition (reaction temperature) and not the heating method (microwaves or conventional heating) is the root cause of the acceleration.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Investigation into the Non‐Thermal Microwave Effect on the Ring‐Opening Polymerization of ε‐Caprolactone

Li¹,

Liao²,

Liu³

2007

Macromol. Rapid Commun.

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Rate constants of the ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) by microwave heating (MH) and flash conventional heating (FCH) have been measured. The reaction is catalyzed by stannous octanoate (Sn(Oct)2). With a microwave power level of 400, 500, 600, 700 and 800 W, the equilibrium temperature of the polymerization mixture increases from 165 to 180, 197, 213 and 228 °C. However, the rate constant does not continuously increase with the observed increase in temperature. Instead it abruptly increases at 180 °C (500 W), and the increase does not fit Arrhenius' law which, however, is followed by the polymerization under FCH conditions with an increase of the equilibrium temperature from 108 to 135, 151, 189 and 213 °C. The initiation time of the ROP by MH varies anomalistically with temperature and is not related to the rate constant, which is in contrast to that by FCH, which reduces exponentially from 127.5 to 36.40, 8.63, 1.22, and 0.579 min with the increase in polymerization temperature and rate constant. Based on the divergences it is reasonable to deduce that the acceleration of the ROP of ε‐CL by microwaves is induced not only by thermal conditions (the thermal microwave effect) but also by the non‐thermal microwave effect.

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Microwave Accelerated Polymerization of 2‐Phenyl‐2‐oxazoline: Microwave or Temperature Effects?

Cited by 37 publications

References 25 publications

One Decade of Microwave‐Assisted Polymerizations: Quo vadis?

One Decade of Microwave‐Assisted Polymerizations: Quo vadis?

Poly(2‐oxazoline)s: Alive and Kicking

Kinetic Investigation into the Non‐Thermal Microwave Effect on the Ring‐Opening Polymerization of ε‐Caprolactone

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