Transesterification cure for coatings: catalysis by epoxy and nucleophiles

Craun, Gary P.; Kuo, Cheng-Yih; Neag, C. M.

doi:10.1016/s0300-9440(96)00658-3

Cited by 10 publications

(11 citation statements)

References 8 publications

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“…The range of functional groups used to acquire reversibility is expanding rapidly, as can be seen in Scheme 1 . The most commonly reported CANs utilized for the self-healing properties include Diels-Alder reactions [ 15 , 16 ], nitroxides [ 17 ], acylhydrazone bonds [ 18 ], disulfide-bonds [ 19 , 20 ], hemiaminal linkages [ 21 ], as well as those involved in ring-opening [ 22 ], and trans-esterification reactions [ 23 ]. Non-covalent adaptable networks (Non-CANs) such as those based on van der Waals forces [ 24 ], transition metal–ligand interactions [ 25 ], π−π interactions [ 26 ], host–guest chemistry [ 27 ], and hydrogen bonding [ 28 , 29 ], are also commonly reported to exhibit self-healing performance.…”

Section: Introductionmentioning

confidence: 99%

Covalent Adaptable Network and Self-Healing Materials: Current Trends and Future Prospects in Sustainability

2020

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This work estimates that if the growth of polymer production continues at its current rate of 5% each year, the current annual production of 395 million tons of plastic will exceed 1000 million tons by 2039. Only 9% of the plastics that are currently produced are recycled while most of these materials end up in landfills or leak into oceans, thus creating severe environmental challenges. Covalent adaptable networks (CANs) materials can play a significant role in reducing the burden posed by plastics materials on the environment because CANs are reusable and recyclable. This review is focused on recent research related to CANs of polycarbonates, polyesters, polyamides, polyurethanes, and polyurea. In particular, trends in self-healing CANs systems, the market value of these materials, as well as mechanistic insights regarding polycarbonates, polyesters, polyamides, polyurethanes, and polyurea are highlighted in this review. Finally, the challenges and outlook for CANs are described herein.

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Section: Introductionmentioning

confidence: 99%

Covalent Adaptable Network and Self-Healing Materials: Current Trends and Future Prospects in Sustainability

2020

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“…The epoxy–acid chemistry is complex as it involves different possible reactions: the most important reactions that take place in stoichiometric formulations are the epoxy–acid addition, the transesterification of the resulting β‐hydroxyester and the condensation between the acid and the hydroxyl group 31–33. The alkoxide anions generated by the epoxy ring opening catalyse the transesterification and also initiate the epoxy homopolymerization 34, 35. In solution, we selected to work with an excess of carboxylic groups and we reasonably assumed that, at the liquid–liquid interface, the reaction takes place by the opening of the epoxy ring by the carboxylic group, with the formation of a hydroxyester.…”

Section: Resultsmentioning

confidence: 99%

Interfacial polymerization of an epoxy resin and carboxylic acids for the synthesis of microcapsules

Pascu

García-Valls

Giamberini

2008

Polymer International

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BACKGROUND: Microencapsulation technology promises new applications such as intelligent microstructures, phase change materials and self-healing composites. Microcapsule synthesis and characterization have been researched extensively; however, the well-known polymerization between epoxy resins and carboxylic acids has not been used to prepare microcapsules. RESULTS: Microcapsules were prepared by interfacial polymerization of an oil-in-water emulsion which contained a commercial epoxy resin and multifunctional carboxylic acids. The microcapsules obtained were characterized using optical microscopy and scanning electron microscopy. Experiments performed at lower stirring rates led to larger microcapsules, in the range 100-400 µm, while higher stirring rates resulted in microcapsules in the range 10-50 µm.CONCLUSIONS: Microcapsules can be prepared by interfacial polymerization of epoxy resins, an extensively studied and widely used class of polymers. By means of NMR characterization we gained insight into the mechanism of polymerization at the interface wherein products coming from the more hindered ring opening as well as from intermolecular transesterification are identified. The presence of a crosslinker affects the morphology of the external microcapsule surface.

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“…The transesterification is particularly important in the formulations containing an epoxy excess due to the high catalytic activity of the alkoxide anion generated by reactions (3) and (4) of Figure 1. [5,6] An indirect confirmation of the assignment of peaks was made by performing a similar polymerization replacing PA by behenic acid, CH 3 (CH 2 ) 20 COOH. Due to the increase in molar masses, the peaks appeared shifted to the higher retention times except for the small peak at 23.1 min that was present exactly at the same position.…”

Section: Sequence Of Reactions At 90 8cmentioning

confidence: 99%

“…In the presence of tertiary amines and in the formulations containing an epoxy excess, main reactions are those shown in Figure 1. [2][3][4][5][6] The epoxy-acid addition (1) and the transesterification (2), are the most important reactions taking place in the stoichiometric formulations. [2][3][4] In these formulations the epoxy-acid addition takes place first, followed by transesterification of the resulting b-hydroxy ester.…”

Section: Introductionmentioning

confidence: 99%

“…This is due to the catalytic effect of the alkoxide anions generated by reactions (3) and (4). [5,6] These alkoxide anions initiate the epoxy homopolymerization indicated by reactions (5) and (6) as shown in Figure 1. Chain transfer and the chain termination reactions, not indicated in Figure 1, do also take place leading to relatively short polyether chains produced by the epoxy homopolymerization.…”

Section: Introductionmentioning

confidence: 99%

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Epoxies Modified by Palmitic Acid: From Hot‐Melt Adhesives to Plasticized Networks

Hoppe

Galante

Oyanguren

et al. 2005

Macro Materials & Eng

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Summary: Reactions taking place in a homogeneous solution of an epoxy monomer based on the diglycidyl ether of bisphenol A (DGEBA) and palmitic acid (PA), in the presence of benzyldimethylamine (BDMA), were investigated using Fourier‐transformed infrared spectroscopy (FTIR) and size exclusion chromatography (SEC). In the stoichiometric formulations prepared with equal molar ratios of epoxy (E) to carboxyl groups, E/PA = 1, the main reaction was the carboxyl addition to the epoxy giving a β‐hydroxy ester. This reaction was followed by transesterification that occurred to a very small extent. In the formulations prepared with an epoxy excess, E/PA > 1, the transesterification reactions were very significant as well as the homopolymerization of the epoxy excess that took place to an almost complete conversion. Reaction products synthesized in the range of 1 < E/PA < 2 were solids at room temperature due to the crystallization of a fraction of fatty acid chains. Above the melting temperature, reaction products recovered the liquid state. The formulation synthesized with E/PA = 2 exhibited a good behavior as a hot‐melt adhesive of steel sheets with a single lap‐shear strength of 2.5 MPa and an interfacial‐cohesive failure. For E/PA > 3, the gelation took place leading to the networks exhibiting a single glass transition temperature (Tg) without any evidence of crystallization or phase separation. Tg varied from 90 °C for the neat epoxy to 0 °C for the formulation with E/PA = 3.Single lap‐shear strength values of hot‐melt adhesives corresponding to reaction products synthesized with E/PA = 1.6, 1.8, and 2.magnified imageSingle lap‐shear strength values of hot‐melt adhesives corresponding to reaction products synthesized with E/PA = 1.6, 1.8, and 2.

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Transesterification cure for coatings: catalysis by epoxy and nucleophiles

Cited by 10 publications

References 8 publications

Covalent Adaptable Network and Self-Healing Materials: Current Trends and Future Prospects in Sustainability

Covalent Adaptable Network and Self-Healing Materials: Current Trends and Future Prospects in Sustainability

Interfacial polymerization of an epoxy resin and carboxylic acids for the synthesis of microcapsules

Epoxies Modified by Palmitic Acid: From Hot‐Melt Adhesives to Plasticized Networks

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