Microwave-Assisted Cationic Ring-Opening Polymerization of 2-Oxazolines

Luef, Klaus Peter; Hoogenboom, Richard; Schubert, Ulrich S.; Wiesbrock, Frank

doi:10.1007/12_2015_340

Cited by 26 publications

(20 citation statements)

References 101 publications

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“…Subsequently, the vial was sealed under inert conditions and the mixture heated at 140˝C for 2 h. The product was recovered as a white solid in a quantitative yield by removal of the solvent. 1 Seventy-five milligrams of methyl tosylate were dissolved in 9 mL of dry dichloromethane in a 20 mL microwave vial. 8.450 g of 2-dec-9 1 -enyl-2-oxazoline were added.…”

Section: Polymer Synthesesmentioning

confidence: 99%

“…Their common structural motif is the amide bond of their side-chains; hence, poly(2-oxazoline)s may be referred to as pseudo-polyamides. The properties of these polymers can be adjusted by in situ and polymer analogous reactions [ 1 , 2 , 3 ]. In the last decade, crosslinking of these materials by (co)polymerizations with (at least) bifunctional 2-oxazoline monomers ( in situ approach) [ 4 , 5 ] as well as the UV-induced crosslinking (often by “click” reactions during a polymer analogous approach) [ 6 , 7 , 8 ] have received renewed attention, benefiting in part from the increased research activities in the area of poly(2-oxazoline)s that coincides with the advent of microwave reactors in polymer scientists’ laboratories [ 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

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Crosslinked Poly(2-oxazoline)s as “Green” Materials for Electronic Applications

et al. 2015

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Poly(2-nonyl-2-oxazoline) 80 -stat-poly(2-dec-9 1 -enyl-2-oxazoline) 20 and poly(2-dec-9 1 -enyl-2-oxazoline) 100 can be synthesized from the cationic ring-opening polymerization of monomers that can be derived from fatty acids from renewable resources. These (co)poly(2-oxazoline)s can be crosslinked with di-and trifunctional mercapto compounds using the UV-induced thiol-ene reaction. The complex permittivity of the corresponding networks increases with the temperature and decreases with the network density. In a frequency range from 10´2 to 10 6 Hz and at temperatures ranging from´20 to 40˝C, the changes of the real part of the complex permittivity as well as the loss factor can be explained by interfacial polarization within the material. At a temperature of 20˝C and a frequency of 50 Hz, the permittivity of the crosslinked (co)poly(2-oxazoline)s covers a range from 4.29 to 4.97, and the loss factors are in the range from 0.030 to 0.093. The electrical conductivities of these polymer networks span a range from 5ˆ10´1 2 to 8ˆ10´9 S/m, classifying these materials as medium insulators. Notably, the values for the permittivity, loss factor and conductivity of these copoly(2-oxazoline)s are in the same range as for polyamides, and, hence, these copoly(2-oxazoline)-based networks may be referred to as "green" alternatives for polyamides as insulators in electronic applications.

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Section: Polymer Synthesesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Crosslinked Poly(2-oxazoline)s as “Green” Materials for Electronic Applications

et al. 2015

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“…No other polymer class has benefited from the advent of microwave reactors in chemical laboratories like the poly(2-oxazoline)s. These polymers and corresponding copolymers can be synthesized by the cationic ring-opening polymerization of 2-oxazoline monomers ( Scheme 1 ), which inherently bears the advantage to introduce a variety of functionalities in their side-chains [ 1 – 4 ]. The structural motif of 2-oxazolines is the five-membered heterocycle containing an oxygen atom and a nitrogen atom (and one double bond).…”

Section: Introductionmentioning

confidence: 99%

UV-mediated thiol-ene click reactions for the synthesis of drug-loadable and degradable gels based on copoly(2-oxazoline)s

Luef

Petit

Ottersböck

et al. 2017

European Polymer Journal

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An 80-membered library of gels composed of monofunctional 2-ethyl-2-oxazoline and 2-nonyl-2-oxazoline and one of four selected difunctional 2-oxazolines (containing either ether or ester bonds) were synthesized by microwave-assisted ring-opening polymerizations. The difunctional 2-oxazolines were prepared from the thiol-ene reaction of glycol dimercaptoacetate or 2,2′-(ethylenedioxy)diethanethiol and 2-but-3′-enyl-2-oxazoline or 2-dec-9′-enyl-2-oxazoline. 53 of the gels exhibited glass-transition temperatures, which ranged from −5.9 to 45.3 °C. 13 Derivatives exhibited glass-transition temperatures in the range from 20 to 30 °C, which renders them stiff at room temperature and flexible at body temperature. The gels that did not contain any 2-ethyl-2-oxazoline acted as lipogels, whereas the gels that did not contain any 2-nonyl-2-oxazoline acted as hydrogels; all other gels may be classified as amphigels. The swelling degrees were measured by gravimetry and maximum swelling degrees of 6 (in water) were observed for the gels with the lowest degrees of crosslinking. In a second approach, the synthesis of crosslinked networks had been achieved by performing the polymeranalogous thiol-ene reaction of copoly(2-oxazoline)s containing olefinic side-chains and glycol dimercaptoacetate. This soft strategy enabled the straightforward loading of such gels with active pharmaceutical ingredients without altering them. This method delivered gels with selected composition exhibiting a targeted disc-shape and loaded with active pharmaceutical ingredients from one-step syntheses. The maximum swelling degrees of these specimens were found to be in accordance with the ones from the first route investigated. Preliminary degradation studies were performed at 25 °C; these types of gels were found to be degraded in alkaline media as well as by esterases.

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“…Due to the interaction and thermal movement of the molecules, the rotational movement of the molecules is blocked and internal friction occurs. As a result, the temperature rises rapidly, which forms a violent reaction and increases the active of polymerization 36‐38 …”

Section: Resultsmentioning

confidence: 99%

Microwave‐assisted ring‐opening copolymerization and property of polycarbonates

Feng

Mei

Fan

et al. 2021

Polymers for Advanced Techs

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Recently, the microwave‐assisted heating method has become a commonly used and environmentally friendly heating technology in the field of organic and polymeric synthetic chemistry. A series of poly(5,5‐dimethyl trimethylenecarbonate‐co‐2‐phenyl‐5,5‐bis[oxymethyl] trimethylenecarbonate) (P[DTC‐co‐PTC]) were synthesized by microwave‐assisted ring‐opening polymerization of 5,5‐dimethyl trimethylene carbonate (DTC) and 2‐phenyl‐5,5‐bis(oxymethyl) trimethylene carbonate (PTC) using tin(II) 2‐ethylhexanoate and aluminum isopropoxidase, the catalysts. These co‐polycarbonates were further reduced by a palladium‐carbon catalyst (Pd/C catalyst, 10%) to make partly deprotected polycarbonates (HPDPC). These two co‐polycarbonates were characterized by gel permeation chromatography, 1HNMR, Fourier transform infrared spectroscopy, UV, differential scanning calorimetry, and automatic contact‐angle measurements. The influences of the microwave irradiation time, microwave power, monomer feed molar ratio, different catalysts, and monomer/catalyst feed molar ratio on the molecular weights of co‐polycarbonates were also investigated. In vitro water absorption, degradation and drug release tests indicated that partly deprotected co‐polycarbonate HPDPC possessed greater hydrophilicity, faster degradation rate, and faster drug release rate than that of corresponding P(DTC‐co‐PTC). Therefore, microwave‐assisted polymerization is a clean and cheap heating method and can be used for ring‐opening copolymerization of carbonates, which enhances the hydrophilicity and biodegradation rate of aliphatic polycarbonates.

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Microwave-Assisted Cationic Ring-Opening Polymerization of 2-Oxazolines

Cited by 26 publications

References 101 publications

Crosslinked Poly(2-oxazoline)s as “Green” Materials for Electronic Applications

Crosslinked Poly(2-oxazoline)s as “Green” Materials for Electronic Applications

UV-mediated thiol-ene click reactions for the synthesis of drug-loadable and degradable gels based on copoly(2-oxazoline)s

Microwave‐assisted ring‐opening copolymerization and property of polycarbonates

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