Are those daily necessities that claim to use "nanomaterials" just a waste of money?

With the development of nanotechnology and nanomaterials, various functional materials have gradually introduced nanomaterials as additives to improve specific performance, such as anti-inflammatory and antibacterial, anti-aging, and catalysis .

For example, adding a certain amount of nano-silicon dioxide to rubber can improve the physical and mechanical properties of rubber, increase its wear resistance, tensile strength, tear strength and hardness, and play a reinforcing role [1]. Adding a small amount of layered hydrotalcite nanomaterials to plastics and rubber can improve flame retardancy, UV resistance and other properties [2,3].

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Nowadays, more and more daily products are labeled as using advanced nanomaterials to enhance product performance , and even develop unprecedented new functions. So are these products using nanomaterials really as advertised? Are nanomaterials really that magical?

Today, let’s talk about nanomaterials.

01

What is Nano?

First of all, what is nano? In fact, it is a unit of length . 1 nanometer (nm) is equal to one billionth of 1 meter, which is roughly equivalent to the length of 10 hydrogen atoms arranged together. It is generally believed that materials with a dimension less than 100 nm in three-dimensional space can be called nanomaterials. The processes and methods related to the preparation, processing and application of nanomaterials are collectively referred to as nanotechnology .

Since humans first discovered the nanoworld through scanning tunneling microscopes in the 1980s, nanotechnology and nanomaterials have developed rapidly in the following decades and have made their mark in various fields.

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When the material size reaches the nanoscale, it usually has properties that bulk materials do not have . This is mainly because the surface atoms of nanomaterials are very active and have relatively high reaction activity. In addition, the existence of quantum size effects gives them special physical and chemical properties, including optical properties, conductivity, catalytic activity, and antibacterial properties.

Take gold as an example. The ordinary bulk material is a golden solid with good conductivity and ductility. However, when it becomes a nanomaterial, it can be stably dispersed in a solvent to form a sol, and presents different colors depending on the size and shape of the gold nanomaterial [4].

Among them, gold nanomaterials that absorb infrared or near-infrared light can also be used for photothermal therapy of cancer . As carbon materials with good biocompatibility, when they are transformed from conventional carbon materials into single-layer graphene, their electrical and thermal conductivity are significantly improved.

02

Nano products in daily life

So, can the products mixed with nanomaterials that we see in our daily lives also have such magical effects? Is the content of nanomaterials in the products high? In fact, for nanomaterials, the root of their special properties is their nanoscale size .

However, nanomaterials are not easy to disperse stably due to their large specific surface area and active properties. Therefore, they tend to aggregate and lose their original properties when preparing composite materials. It is difficult to prepare products that fully retain the properties of nanomaterials.

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At the same time, the manufacturing cost of nanomaterials is high, and it is difficult to make functional products entirely out of nanomaterials. For example, graphene underwear has multiple functions such as sterilization and sweat absorption . Although graphene is also a carbon material, its preparation process requires high requirements and is difficult to mass produce. Each gram of graphene product is worth about 1,000 yuan. To make a pair of underwear entirely out of graphene, the conservative estimate is that the cost would be tens of thousands of yuan.

However, the products we buy are only a few hundred yuan or even tens of yuan, which means that the content of nanomaterials in the products is definitely not very high. In addition to the above-mentioned exaggerated propaganda, there are some that are "made out of thin air".

For example, the nano suit, which claims to be able to "balance yin and yang, dredge meridians, and play a comprehensive role in the health of the body", mentioned in its promotion: when the nano cloth is close to the human skin, it can rely on the extremely strong catalytic decomposition effect to decompose the garbage on the blood vessel wall and excrete it out of the body through new metabolism. Such products are obviously fictitious and exaggerate their functions. Even if the nano material has certain effects, it is impossible to replace existing medical methods .

Despite the exaggerated publicity of these daily products, nanotechnology and nanomaterials do play an increasingly important role in the military, science and technology and other fields.

For example, the super-hydrophobic material designed based on the bionic structure of the lotus leaf surface has the characteristics of water resistance, oil resistance and dust resistance, which is of great significance in the cleaning of precision equipment and surfaces. If ordinary daily necessities have the word "nano", people don't need to worship them too much, just treat them as normal commodities .

In the future, we hope to further develop nanotechnology and truly use nanomaterials in ordinary daily necessities to enhance user experience.

Author: Yuan Zhiqin, Associate Professor, Beijing University of Chemical Technology

Review | Xiong Bin Associate Professor, College of Chemistry and Chemical Engineering, Hunan University

References:

[1] Wu Fan, Wu Xinmin, Song Yonghai, Wang Song, Huai Le, Song Qiusheng. Preparation and properties of silica hybrid modified chlorinated polyethylene rubber[J]. Synthetic Rubber Industry, 2017, 40(04), 267-270.

[2] Liu Yilin, Han Deman, Wang Pengfei, Bao Jianshe, Huang Guobo, Xiang Junwei. Preparation of intumescent flame retardant functionalized hydrotalcite and research on flame retardant modified EPDM foam material[J]. Special Rubber Products, 2016, 37(03), 1-6.

[3] Cao Jiangyong, Liu Zhiguo, Wan Jijun, Wang Shudong, Liu Jinpeng. Effect of acid absorbent hydrotalcite on the properties of chloroprene rubber[J]. Rubber Industry, 2022, 69(05), 352-356.

[4] Zhou, H., Yang, H., Wang, G., Gao, A., and Yuan, Z. (2019). Recent Advances of Plasmonic Gold Nanoparticles in Optical Sensing and Therapy. Current Pharmaceutical Design, 2019, 25(46), 4861-4876.

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