100 times stronger than steel—this Bengaluru company's nanotubes catching Navy, Tesla's eye

2022-12-20 16:36:50 By : Mr. Green Lu

N estled among the trees and winding roads in Bengaluru’s Electronic City is a small, odd trapezium-shaped building that’s pushing into those realms of science where few have gone before. It’s the home of NoPo Nanotechnologies, one of the few companies on the planet to manufacture one of the strongest and tiniest materials ever produced in the world: Single-walled carbon nanotubes or SWCNTs. These are cylindrical structures of single-layered carbon atoms. This microscopic material is 10,000 times thinner than a single strand of human hair and has a tensile strength that is over 100 times that of steel. It also posseses excellent electric and thermal conductivity.

To the naked eye, it appears as crumbly fibres that are stored in tiny airtight containers. Fiberglass Sheets And Resin

NoPo is the only company in the world that manufactures carbon nanotubes of such small diameters. It has already attracted the attention of NITI Aayog, the Navy, and Elon Musk’s Tesla Motors.

The company was started by Gadhadar Reddy in 2011. Reddy grew up fascinated with outer space, Mars, and science-fiction writer Arthur C. Clarke’s ‘space elevators’ tethering structures on the earth to those in the orbit.

Should these elevators become a reality, they will most likely be made with a material like carbon nanotubes. Reddy’s long-term goal is to eventually reach Mars after making access to earth’s orbit commonplace—with this material of the future.

“When you look at stories of those who wanted to make a big impact, [you learn that] they set an audacious goal, paired it with [a] strong desire, and worked backwards. That’s exactly what I sought to do,” Reddy told ThePrint in NoPo’s conference room adorned with NASA’s space travel artwork and infographics designed by the popular YouTube science channel Kurzgesagt.

To work in space travel economy, Reddy stresses on the need for a strong and lightweight material perfectly suited for space. His academic interest in quantum physics gave him the idea to work on carbon nanotubes.

Unlike plants that produce heavy-duty materials in industrial reactors, NoPo Nanotechnologies does all its manufacturing within its small building. The company churns out kilometres-long product that are scrunched up for storage.

Carbon nanotubes today are as revolutionary as stainless steel was when the market first heard of the material. But experts are still working on the process of refining them to make them suitable for industrial-scale use. Right at the forefront is Reddy’s company. Working in labs with glass walls covered with materials science equations, the team produces a substance that will soon be used to build not just spacecraft but also automotives, computers, batteries, water filters, fertilisers, clothes, medicines, and more.

A gram of NoPo’s nanotubes, when laid out flat, covers an area of 1,000 sq. metres. The futuristic material is already in demand—Tesla Motors wants them for making batteries and the Indian goverment for wastewater treatment.

With highly-coveted innovation grants from NITI Aayog and the Indian Navy, the company is also hoping to transform water filtration systems across the country, especially in rural areas.

“If we look at history, we can see revolutions shaped by wood, then stone, then bronze, and [then] iron. Carbon nanotubes are next,” says Reddy.

“Since the material was discovered in the ’90s, there has been a lot of hype that this is the material of the future because it is lightweight and its strength is off the charts. Not only is it very interesting as a quantum material, it is also biocompatible and can be theoretically integrated inside the human body,” he adds.

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To develop carbon nanotubes, Reddy looked to the few academic labs that were able to create them in 2011.

Single-walled nanotubes are produced through a process known as high-pressure carbon monoxide, or HiPCO, developed by Richard Smalley in 1999 at Rice University, US. Smalley had shared the 1996 Nobel Prize in Chemistry with Robert Curl and Harold Kroto for discovering closed fullerenes, an allotrope or different physical form of atomic carbon.

Robert Kelley Bradley was a PhD student under Smalley and worked on the design of the reactors, refining the first reactors that produced SWCNTs. He joined NoPo as co-founder in 2011.

“When I first reached out to Bradley and told him I plan to produce continuous and scalable quantities of carbon nanotubes in India, he told me I was bonkers to attempt it without the necessary laboratory facilities that don’t exist anywhere in the world, and without any experience,” recalls Reddy with a laugh.

But after Reddy said that he would procure funding and dedicate a whole decade of his life to this extension of Bradley’s work, the latter came onboard as an advisor. Reddy first approached the Ministry of Science and Technology, but couldn’t get support in any form as manufacturing SWCNTs was a novel idea that lacked a prototype. He ultimately turned to his uncle who owned a company called Srishti Automations with a machine shop in Jigani in Bengaluru.

Reddy set up a small shed in the company’s premises and started to build a reactor. Helped by his father, he kept the costs low by doing all the grunt work himself and not hiring in the early days.

“I worked like it was a research project,” reminisces Reddy. “Whenever I ran into a problem, I looked up academic papers and reached out to experts in the field, nearly all of whom were outside India.”

Reddy worked on the reactor designs for three years before he could produce the first stable lump of nanotubes. They were 0.8 nm in diameter.

He took the sample to the Central Manufacturing Technology Institute. There he saw that premier labs in the country could only produce up to 50 nm-wide tubes and had electron microscopes with the highest resolution of just 1.3 nm.

Lab experts had to zoom in to the point that even breathing around the microscope was affecting the output. So they took an image of the sample and put that under the microscope.

And then they saw just how small the nanotubes were.

“This is always the case whenever we take our sample to labs,” Reddy says with a smile. “No one believes we have samples that have such small diameters. So we just give them the samples and ask them to check it out for themselves under their most powerful microscopes.”

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NoPo produces the nanotubes in a temperature- and humidity-controlled reactor chamber. “We use carbon monoxide as source for carbon at one end, and iron as catalyst at the other end, which, under high temperature and pressure, splits into iron particles, carbon, and carbon dioxide. The carbon atoms cluster on iron particles and form nanotubes that are 1 mm long with varying diameters,” explains Anto Godwin, chief operating officer at NoPo.

Experts then clean the SWCNTs in another chamber to remove the iron particles. The final product is microscopic and comes either in the form of a powder made up of hair-like fibres or as thin sheets. Each fibre, just about 1 μm long, is composed of pure carbon tubes that are 0.6-1 nm in diameter, single-atom-thick, and weigh next to nothing. The carbon dioxide by-product is turned to carbon monoxide and is reused for the process.

The company produces the nanotubes inside customised reactors, which, too, are manufactured under its roof.

Since 2018, NoPo has been the only company to scale up the HiPCO method through its patented process.

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Due to their large aspect ratio (length divided by diameter) carbon nanotubes are considered to be very good filler materials for composites, which are materials that are made of two or more substances. It’s where nanotubes find maximum use and highest potential today.

Nanotubes are also counter-intuitive. Individual tubes, about 1 nm in diameter, are probably some of the strongest materials in the world. But when the tubes are joined together to form a fibre or mesh, they don’t really hold by themselves. They work their magic when they are built into other materials as composites, strengthening them as a result. That is how they are expected to become commonplace — much like how carbon fibre became so widely used.

Nanotubes can also be used for food security, crop protection, pesticide detection, internal nanosensing of plants, nanofertilising, and pollution control.

Unlike SWCNTs, multi-walled nanotubes have been in use since the 1990s owing to their large surface area, in places like fibreglass, automotive bumpers. SWCNTs are just now finding their use.

Today, they are used to make conductive electrodes for batteries, anti-corrosion paints, durable polymers, and fibreglass, among other things. Soon, they are expected to be widely found in solar and other fuel cells’ capacitors, water filtration and desalination systems, spacecraft bodies, spacesuits, agriculture, moisture retention, construction and materials, and even in medicine as they are known to promote cell growth. They could also act as an exoskeleton for both animals and humans in military applications and medical aid.

Nanotubes are non-polluting as they are simply pure carbon atoms that form under extremely high temperatures and pressure like diamonds and graphite. They have been discovered in resin trees after forest fires, in ice cores as old as 10,000 years, and it is also theorised that single-walled nanotubes form naturally in volcanoes.

They have also been inadvertently synthesised by humans in the past without technological means to detect or manufacture them. Nanotubes were detected on pottery pieces excavated from the famous Sangam-age excavation site Keezhadi using Raman spectroscopy. Dating back to sixth century BCE, they appeared as black coating that fortified pottery shards.

While purifying SWCNTs, Reddy and his team realised its potential for use in batteries — as did Tesla Motors. Additionally, the company is also set to work with popular silicon chip manufacturer Taiwan Semiconductor Manufacturing Corporation (TSMC), which will utilise SWCNTs for more efficient performance and computing.

“It will probably not happen overnight, but in a few years, we are going to see devices with the same form factor as today but with 100 times more computing power and even less loss,” says Reddy. He’s now partnering with others to build space vehicles, rocket prototypes, and spaceflight simulators to realise his dream of going to Mars.

The team has started another venture to build spacecraft from reusable vehicles, joining the booming private space sector of India.

“We’ve been trying to figure out what kind of rocket can be realised with nanotubes and how they would be different from the existing ones,” he says. “Probably another decadal project is going to be a single-stage-to-orbit vehicle, the holy grail for rocketry, as we are able to reduce weight to such a large extent.”

But the immediate focus for Reddy’s team is making a world with SWCNT a reality.

Nanotubes will soon be used for creating various composite materials, including bulletproof textiles, manufacturing industries that consume less energy and emit fewer pollutants, regrowing bones and tissues in the human body, as coatings on various surfaces, and in stealth technology. The global nanotube market was valued at $15.3 billion in 2017 and is projected to hit $103.2 billion by 2030. 

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A prominent use case for SWCNTs is molecular water filtration, which could revolutionise the industry and phase out reverse osmosis (RO) systems that discard more water than they treat.

Inspired by a 2016 study that showed that nanotubes — of the kind NoPo makes — could have immense potential in water purification and filtration. The team started a project for water filtration and was one of the first awardees of Elevate 100, a 2017 venture by the Karnataka government to identify and provide financial assistance to early and impactful startups.

This resulted in the development of a water filtration membrane made up of SWCNTs.

Then NoPo received grants from NITI Aayog as well as the Indian Navy through Innovations for Defence Excellence (iDEX) scheme’s Support for Prototype and Research Kickstart (SPARK) grant to develop a desalination system using nanotubes.

“We were able to fine-tune the material and purify it to further reduce the deviation that happens in tube diameters,” says Renjini G.R., scientist who leads the initiative to develop the water membrane. “These filters outperform existing RO water membranes by a factor of 1,000.”

Water gets filtered at a molecular level, and nanotubes’ natural anti-fungal properties prevent slime formation in membranes.

“The team is working on membranes now to be used by the textile industry that purifies wastewater of toxic material before dumping it,” she adds. “On-site tests showed that NoPo membranes outperformed existing ones by four times.”

Just the way nanotubes conduct electrons, they also allow the conduction of water molecules, acting as a molecular filter. Reddy describes the motion of water molecules into a nanotube of diameter 0.8 nm as a “hyperloop for atoms”. He states that the company has achieved a flow rate of 50 litres and 99 per cent rejection of impurities.

The company is now waiting to perform more tests and acquire a licence.

“NoPo actually stands for Not Possible; it is all that I heard when I decided to start this venture and any time we stated we wanted to create something with nanotubes,” says Reddy. “We wanted to show that it is indeed possible.”

“We are building the Rajnikanth of all materials, and we are sitting on a gold mine,” he adds.

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