Self Healing Polymers: The evolution of modern materials

Imagine having a surface coated with materials that could heal itself from damage, kind of like the Wolverine. Next generation of future polymeric materials will be able to do just that. There are countless researches that are aiming to pull that off. Below are just some of the examples that are published on these self-healing polymers.

The First research used nanoparticles and nanotechnology in dental adhesives. This concept relies on encapsulating monomers and catalyst and incorporating it within the polymer matrix. Whenever there is damage, the capsules simply rupture and release the monomers which fill in the crack and polymerize forming a solid bond in between the cracks. It has applications for dental adhesives and since it is in micro-scale, the monomers can reach within the micro-cracks formed from acid etching in the dentin. Ouyang et al. produced nanocapsules made of polyurethane within the polymer matrix made up of TEGDMA. Using this type of material in dental adhesives provided better bond strength and durability of resin tooth bonding.


Another research by William et al., used vascular-based self-healing approach. This technique utilizes micro-vascular networks embedded within the matrix. The advantage of using this type of material is that larger damage could be fixed and can have multiple self-healing cycles. This vascular network can come in two variations, macro-vascular-based smart composite which is larger in volume and can heal macro-cracks while the other one, a micro-vascular-based smart composite which is smaller, therefore could fill in the micro-cracks. The macro-vascular network was actually inspired by the animal and plant circulatory systems. Any damage could be immediately filled with the healing agent and the hardener which are delivered by the vascular networks to the damage sites.
The third method is also another, encapsulation strategy. This team lead by M.F. Montemor used and tested several different healing agents, encapsulating material and matrix. One such example is encapsulating a catalyst within polyurethane capsules, in the presence of silane-based healing agents, added to a matrix made up of vinyl ester. The mechanism of healing includes, first, the rupturing of the capsules when exposed to a crack and its propagation. At this point, the release of healing agents or healing promoters occurs and the healing mechanism is. The agents fill in the cracks and polymerize to partially or fully heal the damaged or corroded area. This particular team used urea-formaldehyde microcapsules as containers for silyl esters which is the healing agent and do not require any additional crosslinking agents or catalysts for the polymerization.

Self-healing polymer technology has already found use in manufacturing automobile Surfaces. Once fully developed and tested, it can be expanded to fixing micro-fractures in on an airplane fuselage, windows in skyscrapers and even dams which leads to lower maintenance costs and increased durability.

Jessie Marsh
Biopolymers@memeetings.net
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