Plastic Free Coating Invented

Photo source: pexels.com

For decades, societies have relied on plastics made in all sorts of ways. From packaging, construction, automotive, furniture, to clothing products, plastics have been a necessity in modern life.

However, due to the excessive use, plastics have caused serious environmental impact. There are also findings about how it causes health consequences as well. People and policies are moving from reducing, if not eliminating, plastic. And sustainable alternatives made of natural and compostable products are the key to filling the plastic-free gap.

Paper as Plastic? Choetsu Coating to Replace Plastic

Image source: technology.org from Hiroi et al. 

paper origami crane coated with Choetsu (on the left) and another uncoated paper crane (on the right)

Paper is one accessible alternative, as it is made with recyclable and renewable cellulose fibers from grass and trees. But the main problem with paper is that it does not have the sterile features of plastic. Paper also disintegrates when exposed to liquid.

But good news! A research team from the University of Tokyo discovered a coating that can give paper plastic-like properties.

Professor Zenji Hiroi from the Institute for Solid State Physics at the University of Tokyo recognizes that plastic is problematic because it does not degrade and leaches chemicals when trashed. 

He states, "There are materials that can degrade safely, such as paper, but obviously paper cannot fulfill the vast range of uses plastic can."

Hence, their discovery: Choetsu, a low-cost biodegradable coating that can make paper waterproof and as durable as plastic.

Dipping a paper or paper product into the low-viscosity liquid provides the paper with extra thickness, durability, and water resistance. 

Perhaps more importantly, the coating does not change the paper's biodegradability. which means it'll still decompose in the natural environment. Hiroi explained that all the chemicals used in the resin can break down over time and turn into carbon, water, and sand-like silicon. 

Choetsu Resin Has Antimicrobial Properties

Aside from being cheap and versatile, plastic is also easily sterile. Microbes aren't able to consume it, and therefore it's become an indispensable material in areas like food packaging and health care.

Choetsu is made of titanium dioxide nanoparticles. The chemical, when dispersed in a silica film, can coat the paper in a uniform fashion. This prevents certain bacteria from thriving in the material, unlike with plain paper that can be susceptible to dirt, molds, and other bacteria. 

The coating results from countless trials, spearheaded by the first researcher, Yoko Iwamiya, who worked independently on the project before Hiroi joined.

Choetsu: A Cheap and Viable Plastic-Free Alternative 

So what is the coating made of? Choetsu consists of mostly low-cost and safe chemicals, including methyltrimehoxysilane, isopropyl alcohol, and a small amount of tetraisopropyl titanate. And as previously mentioned, it has titanium dioxide nanoparticles to give the sterile characteristic to paper.

Choetsu can be sprayed on paper structures, for example, on paper food cutlery. Once applied, it can dry fast, and the result is the paper has a thin silica layer that will be waterproof and generally plastic-like.

Aside from being cost-competitive, the process itself of coating the solution can make it applicable to various paper products. It's an up-and-coming solution for those who want plastic-free materials for everyday use.