Hydrogels have shown significant potential in everything
from
wound dressings to
soft robots, but their applications have been limited from
their lack of toughness – until now. A team of scientists at
Hokkaido University have developed a new set of
hydrogel composites or "fiber-reinforced soft composites"
that combine hydrogels with woven fiber fabric to create a
material that is five times stronger than carbon steel.
Composite materials have been around for millennia
and the principle is very simple. A very soft substance like mud
can be made strong enough to make bricks by adding straw as a
tempering material. The same applies to adding crushed pottery
to brick, seashells fragments to ceramic, or glass fiber to
plastic.
The latter is very similar to the fiber-reinforced
hydrogel. Hydrogels are made of hydrophilic polymer chains that
absorb up to 90 percent water. They aren't very strong or
durable, but by adding glass tiny fibers the researchers created
a tough, bendable, stretchable material.
Scanning Electron Microscopy (SEM) images of
the fiber-reinforced hydrogels(Credit:
Hokkaido University)
According to the team, the composite hydrogel is
remarkably strong, probably due to dynamic ionic bonds between
the fiber and hydrogels, and within the hydrogels. In tests
using polyampholyte gels and a single glass fiber measuring 10μm
in diameter, the material turned out to be 25 times tougher than
glass fiber fabric, 100 times tougher than hydrogels, and five
times as strong as carbon steel, based on the amount of energy
needed to destroy them.
"The fiber-reinforced hydrogels, with a 40 percent
water level, are environmentally friendly," says Dr Jian Ping
Gong, "The material has multiple potential applications because
of its reliability, durability and flexibility. For example, in
addition to fashion and manufacturing uses, it could be used as
artificial ligaments and tendons, which are subject to strong
load-bearing tensions."
The research was published in
Advanced Functional Materials.
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