Since the outbreak of the new crown pneumonia epidemic, the demand for masks has increased day by day, and more than 3,000 companies across the country have added mask business. As a key material in the filtering process of masks, meltblown fabrics with a fiber diameter of only one-thirtieth of the hair can be called the "heart" of medical surgical masks and KN95 masks. The supply is very tight, and the market price has increased more than ten times. "A piece of cloth is hard to find."

In order to alleviate the shortage of melt blown cloth in the current market, the Institute of Membrane Science and Technology, School of Chemical Engineering, Nanjing University of Technology, gave full play to its professional advantages and developed a new type of filter material-nano-arachnoid bionic membrane, and applied it to the high-performance membrane mask. In production, use membrane technology achievements to shoulder the mission of fighting the "epidemic".

Miraculous nano cobweb bionic membrane material

The diameter of the nano cobweb bionic membrane fibers is in the range of 100-200 nanometers, and the fibers are interlaced to form a three-dimensional cobweb-like structure, and the size of the formed micropores can be controlled in the range of 0.1 to 0.5 microns. "Compared to meltblown materials with disordered accumulation of fibers and a diameter of more than 1000 nanometers, nano-arachnoid bionic membrane has the advantages of high porosity, small pore size, low filtration resistance, and high filtration accuracy." Professor Zhong Zhong, Nanjing University of Technology Zhaoxiang said.

Generally, the air contains a lot of fine particles with positive and negative charges. When these charged particles in the air pass near the electret, they will be strongly adsorbed on the electret fibers, and the uncharged particles will be The electric field formed by the electret is polarized due to induction and will also be adsorbed on the fiber. The traditional melt blown material itself has a large pore size, and it is necessary to add static electricity to improve the filtration efficiency. The static electricity is affected by the temperature and humidity in the environment and will fail in a short time, so the filtration efficiency is rapidly reduced. Therefore, the traditional melt blown in the market Medical masks made of cloth can only be used once.

According to Zhong Zhaoxiang, the nano cobweb bionic membrane material has the characteristics of high porosity, small pore size, low filtration resistance and high filtration accuracy. It does not need to add static electricity, intercepts pollutants through screening, can effectively filter more than 99% of non-oily particles, effectively intercept various solid aerosols, droplets and viruses, without worrying about the problem of reduced filtration efficiency in the case of liquids, and has a good The breathability does not cause breathing discomfort.

Overcome obstacles such as water washing and alcohol disinfection

At present, most medical surgical masks on the market are disposable, and the longest use time is four hours. Although KN95 masks have a longer use time, they cannot be used repeatedly for a long time. This is because the meltblown material that adsorbs pollutants through charging is prone to electrostatic neutralization when it encounters water, which will reduce the filtration efficiency of the mask. Therefore, the mask produced with meltblown cloth cannot be reused after ordinary cleaning.

"Nano-arachnoid biomimetic membrane material has a small pore size, which mainly traps pollutants through physical action, and there is no need to worry about the problem of reduced liquid efficiency." Dr. Wu Junwei, a PhD student in Zhong Zhaoxiang's team, said that the team researchers put the membrane material in water and 75% alcohol After soaking for many times, the filtration efficiency is not affected, and it remains above 99%, indicating that the membrane material mask can be washed with water or disinfected with alcohol and used repeatedly, which greatly increases the utilization rate of the mask.

Wu Junwei said that the results of many comparative experiments conducted by them in terms of service life, reusability and air permeability showed that nano-cobweb bionic membrane material, as a new type of filter material, has better retention and retention than traditional meltblown materials. Breathable performance, so it can be reused and has a longer life.

It can also be used in medical protective clothing and air purifiers

According to reports, the nano-arachnoid bionic membrane material developed by the Membrane Department of the School of Chemical Engineering, Nanjing University of Technology can be used in medical protective clothing, air purifiers and other fields in addition to making masks.

Zhong Zhaoxiang said that the protective clothing made of nano-arachnoid bionic membrane material has good antibacterial and water-repellent properties and is the highest grade medical protective clothing in medical protection. Its characteristic is that human body sweat can radiate outwards, while outside water, bacteria and viruses cannot enter. "The nano-arachnoid bionic membrane material has about 1 billion pores per square centimeter, the porosity is as high as 90%, and the pore size is about 0.2 microns, which is one ten thousandth of the diameter of a water droplet, but it is about 700 times larger than the size of water vapor molecules. Liquid. Water can't get in, but sweat can leak out, so it can achieve excellent waterproof and moisture permeability."

In the industrial field, air purification membranes that have undergone double thinning modification are used for ultra-low emission control of smoke and dust. Hundreds of engineering equipment have been promoted and applied, generating economic benefits of more than 2 billion yuan. At present, air purification membrane materials and membrane masks have been used in hundreds of units, providing a strong guarantee for those who insist on working on the front line of epidemic prevention.