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.
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 Laser. 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.
Yong, J., Zhan, Z., Singh, S., Chen, F., & Guo, C. (2019). Femtosecond Laser-Structured Underwater “Superpolymphobic” Surfaces. Langmuir, 35(28), 9318-9322.
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.