Studying the healing behavior at a microsopic scale

Research in the field of smart materials that exhibit self-repair mechanisms has greatly expanded over the last few years. This is especially true for polymers and polymer composite materials. One class of self-healing polymer materials is the reversible polymer network systems that use dynamic covalent bonds as a means to repair sustained damage. Currently a range of different dynamic covalent bonds is considered, of which the reversible Diels-Alder chemistry has drawn the most attention. Reversible covalent bonds have been incorporated into polymer network structures based on the Diels-Alder reaction between a furan and a maleimide [1-2]. Repair of sustained damage can be established by means of heating-used selfhealing in bulk materials as well as in coating applications. The aim of this research is to study the healing mechanism and healing kinetics at the microscopic scale and to compare this healing mechanism for different polymer network structures and chemistries. The self-healing behavior is studied with local and surface analysis techniques, including Atomic Force Microscopy as an important tool. A better understanding of the healing mechanism at the microscopic level will lead to a better understanding of the macroscopic healing phenomena and ultimately to the adaptation of the polymer network structure to obtain the desired material properties, such as mechanical properties, healing conditions and additional functional properties. The research can then be extended towards self-healing polymer composites, with e.g. a reversible polymer matrix, to evaluate the recovery of the composite material properties [3]

A generic methodology to study self-healing properties of thermo-reversible polymer networks

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A remendable polymer network based on reversible covalent bonding for coating applications

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A new class of supramolecular thermoplastic elastomers for self-healing coatings

A supramolecular material exhibiting self-healing properties was studied in this work. The material is based on the mixture of two ABA-type oligomeric triblock copolymers, the first consisting of positively charged end blocks and the second one of negatively charged ones. Each oligomeric triblock consists of a soft middle block and soft end blocks. When mixed together the resulting material phase-separates in an electrostatically assembled phase with a high glass transition temperature (Tg) and an uncharged phase with a low Tg. The mechanical and physical properties of the resulting thermoplastic elastomer can be tuned by varying the size of the charged blocks, using different polymer architectures and using different monomers. The building block oligomers are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using a bifunctional chain transfer agent and purified by precipitation. Characterization was done by Modulated Differential Scanning Calorimetry (MDSC), Dynamic Mechanical Thermal Analysis (DMTA) and Transmission Electron Microscopy (TEM). The self-healing behaviour of the coating was studied under optical microscope proving self-healing abilities after scratching

Multiple action self-healing coatings for the corrosion protection of metals (abstract)

Materials Science and EngineeringMechanical, Maritime and Materials Engineerin