Microcapsule-based self-healing materials: Healing efficiency and toughness reduction vs. capsule size

Abstract

We report the synthesis of controlled sized Urea-formaldehyde (UF) microcapsules containing an epoxy healing agent via in situ emulsification polymerization for the study of self-healing epoxy systems. Scanning Electron Microscopy (SEM) confirmed that the capsules possessed rough external surface which enhanced mechanical interlocking. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy were employed so as to determine the capsules thermal stability and decompositions and

Self‐healing performance assessment of epoxy resin and amine hardener encapsulated polymethyl methacrylate microcapsules reinforced epoxy composite

“…It is well understood that good interfacial bonding of microcapsules with host matrix improves self‐healing performance and decreases reduction in mechanical properties 4 . Jin et al 17 developed urea formaldehyde dual microcapsule of epoxy monomer, aliphatic polyamine and incorporated them into polymer matrix.…”

“…From the literature survey it is noted that few authors 4,14,18,24 encapsulated epoxy resins in urea formaldehyde and melamine formaldehyde shell walls and few other authors 20,21,25 encapsulated in PMMA shell walls. Some studies 16–19 used dual component system and some studies 9–11 used single component system to evaluate self‐healing performance.…”

“…These smart healing systems offer enhanced service life of the component, improved reliability and durability of the structures. There are several approaches such as microencapsulation, [2][3][4] hollow fibre 5,6 and microvascular networks 7,8 available to develop the self-healing material systems. However, one of the most effective and promising approach is encapsulating healing agent in a fragile walled shell material and integrating those microcapsules with polymer matrix.…”

A Thermosetting Polyurethane with Excellent Self‐Healing Properties and Stability for Metal Surface Coating

“…Polyurethane was mainly a linear or network polymer material containing urethane groups and the separation of hard segments and soft segments often occurred in polyurethane molecules because of the different compatibility of different component. [ 10–13 ] The hard segments are mainly composed of chain extenders and curing agents, which mainly affected the mechanical performance of polyurethane. The soft segments were mainly composed of long chain molecules with active groups at both ends, which affected the elasticity and toughness of polyurethane.…”

Fabrication of microcapsule-type composites with the capability of underwater self-healing and damage visualization

“…[3][4][5] Inspired by the self-healing function of natural organisms, researchers have designed materials that can retain functionalities and restore their structure automatically aer damage to improve the service and safety life of materials. 6,7 Thus, self-healing materials have attracted great attention and resulted in a certain degree of progress in the past decade. [8][9][10] Considering the long-term use of materials in high humidity environment or underwater is inevitable.…”