Polymer/water separation by use of femtosecond laser-structured underwater superpolymphobic mesh

Significance 

The surge in liquid polymer applications has resulted in related polymer pollution effects, causing environmental impacts and various human diseases. Polymers exhibit both liquid and solid states and are typically difficult to biodegrade. To this end, an effective polymer/water separation method is highly desirable. Nevertheless, this has been challenging to accomplish mainly due to the high viscosity, low fluidity, and high adhesion properties of liquid polymers.

Solid surfaces have advantageous abilities to repel liquid polymers in water, a property called underwater superpolymphobicity in this research paper. Existing literature on superpolymphobic materials has shown that these materials have great potentials for use in polymer/water separation because they exhibit excellent polymer repellence and can effectively control adhesion at the water/polymer interfaces. Unfortunately, reports about the use of polymer-repellent microstructures to separate polymer/water mixtures are not available in the literature, at least according to the authors.

In a recent research paper published in the Journal of Colloid and Interface Science, Xi’an Jiaotong University scientists: Professor Jiale Yong, Dr. Xue Bai, Professor Qing Yang, Dr. Xun Hou, and Professor Feng Chen developed a new novel strategy for the filtration and removal of liquid polymers from water. Their approach uses porous underwater superpolymphobic micro/ nanostructures, fabricated by femtosecond laser technique and on a stainless-steel mesh, to repel liquid polymer droplets in water. In their work, the feasibility of this new strategy was verified by using the femtosecond laser structured stainless steel mesh to separate different mixtures of liquid polymers and water.

The authors observed that the resultant microstructured stainless-steel mesh exhibited excellent underwater superpolymphobic properties, resulting in high repellence to various liquid polymers in water. When the mixture of water and liquid polymer was poured onto the prewetted underwater  superpolymphobic mesh, the water in the mixture gradually penetrated through the structured mesh and dripped into the collection beaker below, while the liquid polymer was intercepted by the mesh because of the underwater superpolymphobicity and always remained above the mesh. As a result, the polymer/water mixtures were successfully separated. As such, a high separation efficiency and high separation flux of 99.0% and 4.45 x 105 L m-2 h-1, respectively, was reported. Even though the stainless-steel mesh was susceptible to various damage treatments: abrasion, UV light irradiation, acid, and alkali corrosions, its superpolymphobicity remained relatively stable even after 50 cycles of sandpaper abrasion, 40 cycles of tape peeling, and 12h of exposure to strong acid and alkali corrosion. Scanning electronic microscope (SEM) images revealed the existence of an underwater Cassie contact state between the surface of the laser-treated mesh and the underwater liquid polymer, which largely contributed to the superpolymphobicity of the material. Furthermore, it was worth noting that the underwater superpolymphobicity could be obtained for a wide range of processing parameters.

In a nutshell, the study presented the use of underwater superpolymphobic mesh, produced by femtosecond laser, for separation of mixtures of liquid polymers and water. Results showed that the novel strategy has great potential of separating liquid polymer/water mixtures with high separation efficiency and separation flux. According to Professor Jiale Yong, the new innovative method would help alleviate liquid polymer related pollutions by allowing the recycling of waste polymer resources for use in other areas.

Polymer/water separation by use of the femtosecond laser-structured underwater superpolymphobic mesh - Advances in Engineering

About the author

Prof. Jiale Yong is currently an associate professor at the School of Electronic Science and Engineering at Xi’an Jiaotong University. He received his BS degree from Xi’an Jiaotong University in 2011. After that, he joined Prof. Chen’s research group and received a Ph.D. in Electronic Science and Technology from Xi’an Jiaotong University in 2016. Then, he started to work at Xi’an Jiaotong University.

His research interests include femtosecond laser microfabrication, controlling wettability of solid surfaces, and bioinspired designing superhydrophobic and superoleophobic interfaces.

About the author

Prof. Qing Yang received her BS degree in Photoelectron Science and Technology in 1992 from Sichuan University. In 2009, she received her Ph.D. from Xi’an Institute of Optics and Fine Mechanics, Chinese Academy of Science. She is currently an associate professor at Xi’an Jiaotong University.

Her current research interests are femtosecond laser fine process, microfluidic biochips, and micro-photonics.

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About the author

Prof. Feng Chen is a professor at the School of Electronic Science and Engineering Engineering at Xi’an Jiaotong University, where he directs the Femtosecond Laser Laboratory. He received a BS degree in physics from Sichuan University, China, in 1991, and then began to work for the Chinese Academy of Science (1991 to 2002), where he was promoted to a full professor in 1999. He received a Ph.D. in Optics from the Chinese Academy of Science in 1997. In 2002, he joined Xi’an Jiaotong University, where he became a group leader. His current research interests are femtosecond laser microfabrication and bionic microfabrication.

References

Yong, J., Bai, X., Yang, Q., Hou, X., & Chen, F. (2020). Filtration and Removal of Liquid Polymers from Water (Polymer/Water Separation) by Use of the Underwater Superpolymphobic Mesh Produced with a Femtosecond LaserJournal of Colloid and Interface Science.

Go To Journal of Colloid and Interface Science

Yong, J., Singh, S., Zhan, Z., EIKabbash, M., Chen, F., & Guo, C. (2019). Femtosecond-Laser-Produced Underwater Superpolymphobic Nanorippled Surfaces: Repelling Liquid Polymers in Water for Applications of Controlling Polymer Shape and Adhesion. ACS Applied Nano Materials, 2(11), 7362-7371.

Go To ACS Applied Nano Materials

Yong, J., Zhan, Z., Singh, S., Chen, F., & Guo, C. (2019). Femtosecond Laser-Structured Underwater Superpolymphobic Surfaces. Langmuir35(28), 9318-9322.

Go To Langmuir

Yong, J., Zhan, Z., Singh, S., Chen, F., & Guo, C. (2019). Microfludic Channels Fabrication Based on Underwater Superpolymphobic Microgrooves Produced by Femtosecond Laser Direct Writing.  ACS Applied Polymer Materials, 1(11), 2819-2825.

Go To ACS Applied Polymer Materials

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