TOKYO, Dec 31: In a world-first, scientists have developed a new hydrogel material whose properties are dominated by electrostatic repulsion – the same force that makes our hair stand on end when we touch a van generator.
The advance may pave the way for soft materials with unusual functions, artificial cartilage and anti-vibration materials.
Researchers found that when titanate nano-sheets are suspended in an aqueous colloidal dispersion, they align themselves face-to-face in a plane when subjected to a strong magnetic field.
To create the new material, researchers from the RIKEN Centre for Emergent Matter Science in Japan, along with colleagues from the National Institute of Material Science and the University of Tokyo used the newly discovered method to arrange layers of the sheets in a plane.
Once the sheets were aligned in the plane, fixed the magnetically induced structural order by transforming the dispersion into a hydrogel using a procedure called light-triggered in-situ vinyl polymerisation.
Essentially, pulses of light are used to congeal the aqueous solution into a hydrogel, so that the sheets could no longer move.
By doing this, they created a material whose properties are dominated by electrostatic repulsion, the same force that makes our hair stand on end when we touch a van generator.
Up to now, man-made materials have not taken advantage of this phenomenon, but nature has. Cartilage owes its ability to allow virtually frictionless mechanical motion within joints, even under high compression, to the electrostatic forces inside it.
Electrostatic repulsive forces are used in various places, such as maglev trains, vehicle suspensions and noncontact bearings, but up to now, materials design has focused overwhelmingly on attractive interactions.
The resultant new material, which contains the first example of charged inorganic structures that align co-facially in a magnetic flux, has interesting properties.
It easily deforms when shear forces are applied parallel to the embedded nano-sheets, but strongly resists compressive forces applied orthogonally.
“This was a surprising discovery, but one that nature has already made use of,” said Yasuhiro Ishida, head of the Emergent Bioinspired Soft Matter Research Team.
“We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, based on inspiration from articular cartilage, will open new possibilities for developing soft materials with unusual functions,” said Ishida.
“Materials of this kind could be used in the future in various areas from regenerative medicine to precise machine engineering, by allowing the creation of artificial cartilage, anti-vibration materials and other materials that require resistance to deformation in one plane,” Ishida added.
The study was published in the journal Nature. (PTI)
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