VAN DER WAALS FORCES The material the research team developed is both strong and lightweight, which would allow it to substitute metals and plastics in products like aeroplanes, cars and furniture and because it is biocompatible, biomedical applications may also be in the offing. The material consists principally of cellulose nanofibrils of just 2 to 5 nanometres thickness and about 700 nanometres in length (a nanometre is a millionth of a millimetre).
The nanofibrils suspended in water are force-pressed through a channel just 1 mm wide, and oriented parallel through a smart supply of pure and slightly acid water. The fibres, compressed in this way, adhere to each other by Van der Waals forces, that apply to particles at the nano scale.
The Van der Waals force, named after Dutch scientist Johannes Diderik van der Waals, is a general term used to define the attraction of intermolecular forces between molecules.
The researchers have succeeded in producing threads up to 15 micrometre thick, and several metres in length, says researcher Stephan Roth. The researchers could monitor the process in the X-ray equipment of the German institute DESY, where they could observe precisely how the threads formed.
A lot of development work needs to be done before the still unnamed material can come to the market, but if industrial production would succeed, many applications may lie ahead. The material has a stiffness eight times that of spider silk, and a tensile strength several times higher. It can be woven and then be processed to materials with unique properties, materials stronger than glass fibre composites or steel cables.
The researchers estimate that production costs will be comparable to those of other synthetic strong materials. Moreover, this strongest biomaterial will still be biodegradable, being made just of cellulose. ‘We can now transform the super performance from the nanoscale to the macroscale,’ says researcher Söderberg.
It opens the way for developing nano fibre materials that can be used for larger structures while retaining the nano fibres’ tensile strength and ability to withstand mechanical load.
STRONGEST BIOMATERIAL EVER
The quest for eco-friendlier and energy-efficient technologies accentuates the need to develop lightweight structural materials with exceptional mechanical performance from renewable resources, Nature has developed building blocks with excellent properties.
Lately, scientists have been seeking ideas of mimicking natural materials’ architecture based on engineering design principles, typically called bio-inspired assembly. An overarching challenge in structural material fabrication is to translate the extraordinary mechanical properties of nanoscale building blocks to the macroscale bulk materials.