[materials] Professor Hou Xu's team of Xiamen University uses biomimetic liquid composite organic polymer elastic membrane system to realize the new technology of multiphase separation under constant pressure for the first time

The study of multi-phase separation of membrane science and technology is of great significance in the fields of petrochemical industry, natural gas exploitation, sewage treatment, biomedicine, wet dedusting, fermentation engineering, etc How to realize the dynamic controllable multiphase separation under constant pressure environment has been facing great technical challenges Recently, Professor Hou Xu's research team of Xiamen University has made a breakthrough in this field, and his research results have published the latest research entitled "liquid gathering elastic borous system with dynamically controlled gas / liquid transport" on science advances published by the American Association for the advancement of science Professor Hou Xu's research team has been engaged in the research of multi-scale pore materials for a long time The team proposed the concept of bionic multi-scale intelligent gate control and the design of multi-scale interface Biomimetic multi-scale intelligent gating refers to the micro / nano scale porous membrane materials developed inspired by organisms in nature The membrane pores are stimulated by the external environment, including light, pressure, pH, temperature, humidity, electric field, magnetic field and other responses, which can realize the opening and closing of membrane pores and selectively carry out material transport (adv mater., 2016, 28, 7049-7064) The design of multi-scale interface includes the design of liquid sliding surface of multi-scale pore surface, the design of solid / liquid / liquid interface in multi-scale pore, and the design of dynamic sliding interface in multi-scale pore (small, 2018, 1703283; ACS Nano, 2018, DOI: 10.1021 / acsnano 7b07923) The alveoli in organisms are filled with micro pores, which are filled with liquid The gas enters into the tissue through the channels filled with liquid and exchanges gas The elastic shrinkage of alveoli pores can well realize the liquid gate switch of pressure gradient Inspired by this biological alveolus pore, Professor Hou Xu's research team designed a biomimetic liquid composite organic polymer elastic membrane system Fig 1 alveolus pore in biology, which is a good way to realize liquid gate switch of pressure gradient (picture from network) In this study, functional liquid and organic polymer elastomer materials are combined to form a stable composite membrane system for the first time, which is used for controllable multiphase transport and dynamic separation under constant pressure environment Among them, the functional liquid is stabilized in the elastic porous membrane by capillary force, forming a kind of liquid gating The liquid gating technology transfers the scientific problems of the traditional solid-liquid interface to the liquid-liquid interface, and takes the liquid as a dynamic "gate" to realize the controllable transportation and separation of substances Through the dynamic control of the pore size of the elastomer and the cooperation of the liquid-solid interface, the fluid transport performance is controlled This new composite design idea is expected to be applied to chemical reaction, fuel cell, multiphase flow system, multiphase micro reaction, biomimetic Microfluidics (NAT Rev Mater., 2017, 2, 17016; chin Chem Lett., 2017, 28, 1131-1134; Acta PHY Sin., 2016, 65, 178301), preparation of colloidal particles and other fields This research direction will provide new materials and new technical means for the development of a new generation of multiphase separation system, and promote the development of multiphase transport and separation technology Fig 2 working principle of biomimetic liquid composite organic polymer elastic membrane Firstly, a porous polymer elastomer material with controllable pore diameter is designed The elastomer material has good expansion rate (fracture expansion rate ~ 450%) and stability (cycle stability is more than 500 times) The pressure threshold of the fluid to be transported through the membrane system changes with different pore size design The porous membrane of elastomer has the characteristics of dynamic adjustable pore size and excellent recovery ability Different functional liquids and polymer membrane materials have different wettability By optimizing the wettability conditions, a stable liquid gated composite membrane system was constructed Due to the composite of functional liquid and polymer membrane material, the direct contact between the fluid to be transported and membrane material is avoided, and the system has excellent antifouling performance Fig 3 the interface design of biomimetic liquid composite organic polymer elastic membrane studied the influence of pore size on the pressure threshold of material passing through the membrane from both experimental and theoretical aspects The stress distribution of elastic porous membrane material subjected to one and two dimensional deformation is analyzed The transport properties of materials are controlled from one dimension to two dimensions It is found that the pressure threshold of the fluid to be transported through the composite membrane system can be reduced under the action of one and two-dimensional external forces, and the threshold can be changed dynamically through external forces Each fluid to be transported has a specific transmembrane pressure Under the action of external force, the polymer membrane of liquid composite elastomer will undergo directional deformation, which not only ensures the high permeability of the composite membrane, but also ensures the high selectivity of the composite membrane Fig 4 the gas-liquid separation of biomimetic liquid composite organic polymer elastic membrane is realized under the action of external force Further, a gas-liquid separation fluid device based on biomimetic liquid composite organic polymer elastic membrane is designed For the first time, the controllable gas-liquid transportation and dynamic separation under constant pressure environment are realized (separation efficiency is above 97%) The composite system has a wide range of materials selection, simple preparation, good controllability, high stability, good anti fouling performance and recovery performance, and can dynamically control the membrane pressure of substances This study will be of great significance for the transport and separation of multiphase substances The project has been supported by NSFC (project approval No.: 21673197), the 12th batch of "Thousand Talents Program" youth program of youth overseas high level talent introduction program, the subject innovation and intelligence introduction program of colleges and universities (project approval No.: b16029) and the president of Xiamen University (project approval No.: 20720170050) Paper link: http://advances.sciencemag.org/content/4/2/eaao6724 profile of Professor Hou Xu: http://chem.xmu.edu.cn/teacher.asp? Id = 355 Professor Hou Xu