In science, we have an insane predicament of looking for solutions to problems in the most unforeseen ways, thinking that maybe the most complex solution is always the best. Nothing could be further from the truth.
Nature, after millions of years of evolution, has always given rise to the most satisfactory solutions. It is the classic methodology of trial and error, known as natural selection. It exists, undoubtedly, as a modern trend to look towards the solutions that nature proposes to us and to try to reproduce them. Animals are plants with advanced sensorial mechanisms, high-mechanical resistance shells, high-aerodynamic structures, and new opportunities are opened for biomimetic materials.
We constantly hear people talking about intelligent materials, nanotechnology, advanced benefits, innovation, etc., when nature has always gone one or two steps ahead in getting identical solutions with the means that she has.
In fact, nanotechnology is a concept always assumed and applied by nature. At this point, researchers, engineers and technologists opt to look around them, searching new solutions and developing extremely innovative biomimetic materials that reply or mimetizes the biological processes and materials. A previous needed step in this working method is the previous analysis and reverse engineering: The deep knowledge of the processes used by the live organisms with the environment and that have developed effective systems in order to adapt to it.
We call them elegant solutions, and they really are. For instance, airplane designers took into account the swan's flight, the position of its neck stretched forward, or the "beak of duck," an aerodynamic solution adopted by high-speed trains. The case of the Eiffel Tower building is also a fantastic one, made with especially dense material, iron, but organized in a way that the final structure is light, imitating bone structure and some marine microskeletons, such as the radiolarians.
The research in biomimetic systems, based on polymeric materials, present lots of possibilities for the future, some of them are already or almost available in the market. One of the most followed properties in the polymers world is the formation of self-cleaning and highly hydrophobic surfaces.
Applications related to industries like building or automotive require surfaces cleaned of dust, dirt and repellent to water. Super-hydrophobicity properties are not easy to get.
Nevertheless, we can not miss the known as "lotus effect." Who doesn't remember childhood series like "Maya the Honey Bee" or "The World of David the Gnome" that featured enormous rocio dewdrops rolling by the leaves without being broken down to the ground?
These plants keep the surface clean of dirt, insects, pollution and strange particles by making a complex and rough microtopography formed by natural wax crystals. This particular structure avoids the water adherence in its surface. The placed drops roll catching any organic remain or particle.
There exists a huge number of techniques available in order to proportion this microtopography in any plastic surface. One of the most popular ones includes the depositing of silica nanoparticles through CVD or lithography techniques. Another way is the creation of microroughnesses through a conveniently treated cast in order to proportion that superficial structure. And many more.
The sportive swimsuit and its influence in worldwide brands was a kind of application that was questioned and highly controversial some years ago. Inventions related to biomimetism are joined apart from the already known increased overall polyurethane buoyancy.
The "Riblet effect" makes reference to the shark’s skin, which has microscopic denticles that resemble vertical vortexes and spirals on water, avoiding the apparition of low-pressure areas and turbulent flows. In sum, it reduces the resistance by water friction. Similar solutions have served to develop both swimsuits based on the "shark’s skin," hulls of sportive boats and new research applications in wind tunnels for aerospace and automotive structures that would reduce consumption.
It is also interesting to talk about a natural structure that is an example and summary of excellent mechanical properties. We are talking about mother of pearl.
This structure consists of a high alignment of aragonite, surrounded by a protein that acts as an adhesive as a brick wall. The result is a material with a high number of mechanical and barrier provisions. These natural properties have been imitated through techniques of deposition in plastic or metallic surfaces called “layer-by-layer”. This strategy supposes the preparation of surfaces with 100-500 layers of nanoclays, with a polymer as adhesive (the "brick" that we have mentioned).
The main problem of this application is to scale-up the process of "layer-by-layer" to an industrial level. However, we already can find a commercial application: NANOBRICK.
It is a solution like the one we are talking about, where a 100-nanometer film is deposited, completely transparently, above a traditional PET layer. We get barrier properties up to 100 times higher than other traditional coatings, such as the silicon oxides used in PET bottles or the metallic multi-layers that we can find in the flexible packagings for snacks.
If we could add titanium dioxide nanoparticles or other metal oxides, we would proportion ultraviolet and microbial resistance, which would be remarkable for applications in packagings. But this is other material.
We could keep talking about this topic, discussing promising artificial corneas with hydrogels, or bone coatings with chitosan, or wood structures with nanocelluloses disposed through the "layer-by-layer" technique, or innovative microsensors in textiles based on the solution of the human skin, or the silk of spiders by electro-spinning techniques and many other applications. But the general idea is really clear: Most of the time, the solutions of nature are the most intelligent and efficient. We only have to copy, simulate and improve them.
