Catalytic control of bond exchange reactions enables healing of cross-linked polymer materials under a wide range of conditions. The healing capability at high temperatures is demonstrated for epoxy–acid and epoxy–anhydride thermoset networks in the presence of transesterification catalysts. At lower temperatures, the exchange reactions are very sluggish, and the materials have properties of classical epoxy thermosets. Studies of model molecules confirmed that the healing kinetics is controlled by the transesterification reaction rate. The possibility of varying the catalyst concentration brings control and flexibility of welding and assembling of epoxy thermosets that do not exist for thermoplastics.

Metal-catalyzed transesterification for healing and assembling of thermosets.

https://web.itu.edu.tr/okayo/pdf/00review.pdf

Macroporous copolymer networks

Conventional polyolefins new polyolefins stereoregular polar thermoplastics syndiotactic polystyrene unplasticized polyvinyl chloride (uPVC) - fracture and fatigue properties acrylonitrile-butadiene-styrene (ABS) polymers styrene copolymers polyacrylonitrile polyacrylates polyacrylamides vinyl acetate polymers vinyl alcohol polymers synthetic water-soluble polymers cellulose plastics thermoplastic elastomers thermplastic polyurethanes polyester-based thermplastic elastomers polybutylene terephthalate compatibilized thermoplastic blends toughening of thermoplastics polyacetal polyether polyarylates polycarbonates polyamides polyimides polybenzimidazoles aromatic polyhydrazides and their corresponding polyoxadiazoles polyphenylquinoxalines polyphenylene sulfide polyphenylene vinylene conducting thermoplastics conducting thermoplastics composites poly(aryl ether sulfone)s poly(aryl ether ketone)s poly(aryl ether ketones-co-sulfones) poly(aryl ether ketone amide)s polytetrafluoroethylene liquid crystalline polymers advanced thermoplastics composites.

Handbook of Thermoplastics

Polymer engineering based on reversible covalent chemistry: A promising innovative pathway towards new materials and new functionalities

Modern cationic vinyl polymerization

The mechanism of acid curing of epoxy resins catalyzed with tertiary amines was investigated by using model systems composed of phenylglycidyl ether and benzoic acid or acetic acid anhydrides in the presence of benzyldimethylamine. The reaction was studied by NMR spectrometry, liquid chromatography, and ozone absorption. The main findings are that (1) the tert-amine is bound chemically and irreversibly during the reaction under the formation of a quaternary ammonium salt 

and (2) 1-phenyloxypropanediol-2,3-dibenzoate or diacetate is the main reaction product. The suggested reaction mechanism involves initiation in which the tertiary amine reacts with the epoxy group, giving rise to a zwitterion that contains a quaternary nitrogen atom and an alkoxide anion; the latter immediately reacts with the anhydride and quaternary salt is formed. In a later stage the carboxy anion of the quaternary salt reacts first with the epoxy group, then with the anhydride. By this reaction diester is formed and the carboxy anion is regenerated.

Curing epoxy resins with anhydrides. Model reactions and reaction mechanism

The molar masses of linear polyesters formed in the polymerization of stoichiometric mixtures of 1,7-heptanedicarboxylic acid (4) with 2,2-bis[4-(2,3-epoxypropoxy)phenyl]propane (2) (the diglycidyl ether of Bisphenol A), and of 1,2-cyclohexanedicarboxylic anhydride (3) with 2,3-epoxypropyl phenyl ether (1), catalyzed with tertiary amines, and the effect of the concentration of the tertiary amine catalysts were compared. In the reaction between anhydride 3 and epoxide 1 the molar mass of polyester, determined by GPC, was found to decrease with increasing concentration of the tertiary amine, whereas in the reaction of the acid it is independent of the catalyst content. The molar mass distribution is much narrower in the reaction of the anhydride. These results correspond to the mechanisms determined earlier: a stepwise mechanism in the reaction between epoxide and acid, and an “initiation” mechanism in the case of anhydride. In the polymerization of the dicarboxylic acid 4 with the diepoxide 2 good agreement was observed with the theoretical dependences, calculated by using the theory of branching processes.

Acid curing of epoxy resins. A comparison between the polymerization of diepoxide‐diacid and monoepoxide‐cyclic anhydride systems

Antioxidants and stabilizers. XXXIII. Analysis of stabilizers of isotactic polypropylene: application of gel permeation chromatography

The reaction of diglycidylaniline (DGA) and N-methylaniline (NMA) was investigated by means of HPLC, and the products were identified by mass spectrometry. A number of cyclic products is formed. An eight-membered ring formed by the intramolecular reaction of the secondary amino group and the epoxy group in the DGA-aniline monoadduct is the main cyclic product. The monoadduct DGA-NMA yields a seven-membered ring by internal etherification only after the amine has been consumed.

S. Pokorný

Papers

Curing epoxy resins with anhydrides. Model reactions and reaction mechanism

Acid curing of epoxy resins. A comparison between the polymerization of diepoxide‐diacid and monoepoxide‐cyclic anhydride systems

Antioxidants and stabilizers. XXXIII. Analysis of stabilizers of isotactic polypropylene: application of gel permeation chromatography

Cyclization in the reaction between diglycidylaniline and amine

Concentration effects in gel permeation chromatography