Scientists have tied molecules into the tightest knot ever achieved — a breakthrough that may pave the way for a new generation of light, super-strong and flexible materials. Researchers from University of Manchester in the UK developed a way to braid multiple molecular strands, enabling tighter and more complex knots to be made than has previously been possible.
The breakthrough knot has eight crossings in a 192-atom closed loop which is about 20 nanometres long. Being able to make different types of molecular knots means those scientists should be able to probe how knotting affects strength and elasticity of materials which will enable them to weave polymer strands to generate new types of materials.
"Tying knots is a similar process to weaving so the techniques being developed to tie knots in molecules should also be applicable to the weaving of molecular strands," said David Leigh, a professor at University of Manchester. "For example, bullet-proof vests and body armour are made of Kevlar, a plastic that consists of rigid molecular rods aligned in a parallel structure - however, interweaving polymer strands have the potential to create much tougher, lighter and more flexible materials in the same way that weaving threads does in our everyday world," said Leigh.
"Some polymers, such as spider silk, can be twice as strong as steel so braiding polymer strands may lead to new generations of light, super-strong and flexible materials for fabrication and construction," he said. "We 'tied' the molecular knot using a technique called 'self-assembly', in which molecular strands are woven around
metal ions, forming crossing points in the right places just like in knitting - and the ends of the strands were then fused together by a chemical catalyst to close the loop and form the complete knot," said Leigh. "The eight-crossing molecular knot is the most complex regular woven molecule yet made by scientists," he said. The research was published in the journal Science.
