Modified Rheokinetic Technique to Enhance the Understanding of Microcapsule-Based Self-Healing Polymers

Abstract

A modified rheokinetic technique was developed to monitor the polymerization of healing monomers in a microcapsule-based, self-healing mimicking environment. Using this modified technique, monomers active toward ring-opening metathesis polymerization (ROMP) were either identified or disregarded as candidates for incorporation in self-healing polymers. The effect of initiator loading on the quality and speed of healing was also studied. It was observed that self-healing polymers have upper and lower temperature limits between which the healing mechanism performs at optimal levels. Also, a study of the quality of healing cracks of different thicknesses was performed, and it was discovered that above a critical crack thickness value, the quality of self-healing diminishes substantially; reasons for this phenomenon are discussed in detail.

Evaluation of 5-ethylidene-2-norbornene with an adhesion promoter for self-healing applications

“…Neat ENB has an T onset near room temperature in the presence of second‐generation Grubbs' catalyst, suggesting that this reaction system remains active for practical use without additional stimulus (e.g., heat). As the MNC loading increases, the exothermic peaks, i.e., T onset and T p , shift towards higher temperatures, which is consistent with previous reports that oxygen‐containing norbornene derivatives require more energy or higher temperature to initiate ROMP reactions . Therefore, addition of the MNC monomer will be helpful in designing the cure temperature of ENB‐based healing agents for different self‐healing applications.…”

“…). In addition to improved adhesive strength, the use of MNC is expected to retard the excessively rapid ROMP reactivity of ENB by oxygen‐containing norbornene groups . The second‐generation Grubbs' catalyst was selected as the polymerization initiator, which has demonstrated higher thermal stability, wider chemical resistance, and greater activity for a variety of norbornene olefins .…”

The self‐healing cross‐linked polyurethane by Diels–Alder polymerization

“…Simulated the self-healing process of organism, researchers introduced the concept of self-healing into polymer material in order to get longer, more reliable, more economical new smart functional materials. [10] The other is the intrinsic self-healing materials, which can heal cracks by reversible covalent bonds and/ or reversible non-covalent bonds. [2,3] Currently, self-healing materials can be divided into two categories according to the repair mechanism; one is the extrinsic self-healing materials, which utilize hollow fibers and capsules containing repairing agents such as dicyclopentadiene, [4,5] norbornyl diene, [6] the epoxy/mercaptan, [7] polydimethylsilane.…”

“…But the healing agent can only release autonomously once in one position and the hollow microcapsules or fiber tends to form new defects in materials. [10] The other is the intrinsic self-healing materials, which can heal cracks by reversible covalent bonds and/ or reversible non-covalent bonds. Reversible covalent bonds involve the Diels-Alder group, acylhydrazone bond, disulfide bonds, [11] reversible C-ON bond, aromatic benzene and furan ketone dimer body, [12] tri-thiocarbamates, [13,14] and aryl boric acid ester.…”

Desenvolvimento de novas combinações monômero - catalisador para a produção de polímeros via ROMP

“…Um dos métodos reológicos mais comuns utilizados para monitorar a cinética do processo de polimerização são as medidas oscilatórias dinâmicas [33,[58][59][60] . Neste estudo, utilizando a geometria de placas paralelas, através do domínio das propriedades reológicas da amostra e do tempo de gelificação foi examinada a cinética da reação de ROMP dos sistemas catalíticos: …”