2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. 

Discovery of this noble gas:

In 1894 argon was discovered by chemists Sir William Ramsay and Lord Rayleigh. Ramsay believed the presence of a heavy impurity in the ‘atmospheric’ nitrogen could be responsible for giving nitrogen a higher density when isolated from the air. Both scientists worked to discover this unrecognised new element hiding in the air, winning a Nobel Prize in 1904, primarily for their role in the discovery of argon.

Facts

Argon makes up 1% of the earth’s atmosphere and it is the most plentiful of the rare gases. Argon can be both used in its gaseous state and its liquid form. In its liquid state, argon can be stored and transported more easily, affording a cost-effective way to deliver product supply.

Argon as a narcotic agent

One of the most well-known biological effects of argon gas is in its narcotic capabilities. Sea divers normally develop narcotic symptoms under high pressure with normal respiratory air. These symptoms include slowed mental cognition and psychological instability. Argon exerts this narcotic effect in a physical way rather than in a chemical way, as argon, an inert gas, does not undergo chemical reactions in the body.

3-D Printing

During the heating and cooling of printing materials, argon provides several benefits to this process. The gas reduces oxidation of the metal preventing reactions and keeping out impurities. This creates a stable printing environment as a constant pressure is maintained.

 

Future of argon

Argon as a clinical utility tool has received maximum attention. Although the potential benefits are still in the experimental stages, argon could be the ideal neuroprotective agent. Studies have shown that argon could improve cell survival, brain structural integrity and neurological recovery. These protective effects are also efficient when delivered up to 72 hours after brain injury.

Scientists are closer to developing 3D printed artificial tissues that could help heal bones and cartilage, specifically those damaged in sports-related injuries. Scaffolds for the tissues have been successfully engineered.

Small injuries to osteochondral tissue – a hard bone that sits beneath a layer of cartilage that appears smooth – can be extremely painful and heal slowly. These injuries are very common in athletes and can stop their careers in their tracks. Osteochondral tissue can also lead to arthritis over time.

 

These types of injuries are commonly seen in athletes.

As osteochondral tissue is somewhere between bone and cartilage, and is quite porous and very difficult to reproduce. But now, bioengineering researchers at Rice University, Texas, US, have used 3D printing techniques to develop a material that may be be suitable in future for medical use.

A porous scaffold, with custom polymer mixes for cartilage and ceramic for bone, was engineered. The imbedded pores allow cells and blood vessels from the patient to infiltrate, integrating the scaffold into the natural bone and cartilage.

‘For the most part, the composition will be the same from patient to patient,’ said Sean Bittner, graduate student at Rice University and lead author of the study.

Researchers claim to be ‘on the cusp’ of creating a new generation of devices that could vastly expand the practical applications for 3D and 4D printing. At the ACS meeting in New Orleans in March, H. Jerry Qi at Georgia Institute of Technology reported the development of a prototype printer that not only simplifies and speeds up traditional 3D printing processes, but also greatly expands the range of materials that can be printed.

4D printing would allow 3D printed components to change their shape over time after exposure to environmental triggers such as heat, light and humidity. In 2017, for example, Qi’s group, in collaboration with scientists at the Singapore University of Technology and Design, used a composite made from an acrylic and an epoxy along with a commercial heat source to create 4D objects, such as a flower that can close its petals or a star that morphs into a dome. These objects transformed 90% faster than previously possible because the team incorporated the mechanical programming steps directly into the 3D printing process.

 

H Jerry Qi (right) with Glaucio Paulino, a professor at Georgia Tech’s School of Civil and Environmental Engineering, hold 3D printed objects that use tensegrity – a structural system of floating rods in compression and cables in continuous tension. Image: Rob Felt

‘As a result, the 3D printed component can rapidly change its shape upon heating,’ the researchers reported. ‘This second shape largely remains stable in later variations in temperature such as cooling back to room temperature. Furthermore, a third shape can be programmed by thermomechanical loading, and the material will always recover back to the permanent (second) stable shape upon heating.’

In their latest work, the group sought to create an ‘all-in-one’ printer that combines four different printing techniques: aerosol, inkjet, direct ink write and fused deposition modelling. The resulting machine can handle a range of materials such as hydrogels, silver nanoparticle-based conductive inks, liquid crystal elastomers and shape memory polymers (SMPs). 

It can even create electrical wiring that can be printed directly onto an antenna, sensor or other electrical device. The process uses a direct-ink-write method to produce a line of silver nanoparticle ink, which is dried using a photonic cure unit – whereupon the nanparticles coalesce to form conductive wire. Lastly, the wires are encased in plastic coating via the printer’s inkjet component.

The researchers can also use the printer to create higher quality SMPs capable of making more intricate shape changes than in the past. And to also make materials comprising both harder and softer or more bendable regions, Qi explained. Here, the printer projects a range of white, grey or black shades of light to trigger a polymer crosslinking reaction dependent on the greyscale of shade shone on the component part. Brighter light shades create harder component parts than darker shades.

In terms of applications, Qi’s own particular interest is in developing ‘soft robots’ with sensory properties more akin to human skin than the traditional metallic or rigid robots with which we are probably more familiar. Sensory robots, Qi says, will play a big role in future safety for human workers working alongside robots. As a first step in that direction, his group is currently working with Children’s Healthcare of Atlanta to investigate whether the new technology could make prosthetic hands for children born with malformed arms – a condition not covered by most medical insurance policies. The idea would be to combine multiple different sensors to create a functional replacement hand.

In future, new 3D and 4D printers will ultimately be capable of printing whatever we might want to make, Qi says. He points, for example, to work by Jennifer Lewis at the University of Harvard to 3D print a Li-ion battery – an essential component of mobile phones and computer laptops. However, Qi notes that 3D printing does not always make economic or practical sense for all items. Instead, a big consideration will be ‘pick and place’ technology that mixes and matches printed and non-printed components to assemble the desired objects.

Researchers claim to be ‘on the cusp’ of creating a new generation of devices that could vastly expand the practical applications for 3D and 4D printing. At the ACS meeting in New Orleans in March, H. Jerry Qi at Georgia Institute of Technology reported the development of a prototype printer that not only simplifies and speeds up traditional 3D printing processes, but also greatly expands the range of materials that can be printed.

4D printing would allow 3D printed components to change their shape over time after exposure to environmental triggers such as heat, light and humidity. In 2017, for example, Qi’s group, in collaboration with scientists at the Singapore University of Technology and Design, used a composite made from an acrylic and an epoxy along with a commercial heat source to create 4D objects, such as a flower that can close its petals or a star that morphs into a dome. These objects transformed 90% faster than previously possible because the team incorporated the mechanical programming steps directly into the 3D printing process.

 

H Jerry Qi (right) with Glaucio Paulino, a professor at Georgia Tech’s School of Civil and Environmental Engineering, hold 3D printed objects that use tensegrity – a structural system of floating rods in compression and cables in continuous tension. Image: Rob Felt

‘As a result, the 3D printed component can rapidly change its shape upon heating,’ the researchers reported. ‘This second shape largely remains stable in later variations in temperature such as cooling back to room temperature. Furthermore, a third shape can be programmed by thermomechanical loading, and the material will always recover back to the permanent (second) stable shape upon heating.’

In their latest work, the group sought to create an ‘all-in-one’ printer that combines four different printing techniques: aerosol, inkjet, direct ink write and fused deposition modelling. The resulting machine can handle a range of materials such as hydrogels, silver nanoparticle-based conductive inks, liquid crystal elastomers and shape memory polymers (SMPs). 

It can even create electrical wiring that can be printed directly onto an antenna, sensor or other electrical device. The process uses a direct-ink-write method to produce a line of silver nanoparticle ink, which is dried using a photonic cure unit – whereupon the nanparticles coalesce to form conductive wire. Lastly, the wires are encased in plastic coating via the printer’s inkjet component.

The researchers can also use the printer to create higher quality SMPs capable of making more intricate shape changes than in the past. And to also make materials comprising both harder and softer or more bendable regions, Qi explained. Here, the printer projects a range of white, grey or black shades of light to trigger a polymer crosslinking reaction dependent on the greyscale of shade shone on the component part. Brighter light shades create harder component parts than darker shades.

In terms of applications, Qi’s own particular interest is in developing ‘soft robots’ with sensory properties more akin to human skin than the traditional metallic or rigid robots with which we are probably more familiar. Sensory robots, Qi says, will play a big role in future safety for human workers working alongside robots. As a first step in that direction, his group is currently working with Children’s Healthcare of Atlanta to investigate whether the new technology could make prosthetic hands for children born with malformed arms – a condition not covered by most medical insurance policies. The idea would be to combine multiple different sensors to create a functional replacement hand.

In future, new 3D and 4D printers will ultimately be capable of printing whatever we might want to make, Qi says. He points, for example, to work by Jennifer Lewis at the University of Harvard to 3D print a Li-ion battery – an essential component of mobile phones and computer laptops. However, Qi notes that 3D printing does not always make economic or practical sense for all items. Instead, a big consideration will be ‘pick and place’ technology that mixes and matches printed and non-printed components to assemble the desired objects.