Preparation of porous PTFE/C composite foam and its application in gravity‐driven oil–water separation

Abstract

Porous superhydrophobic filtration media with durable performance that can be used in harsh environments remain an urgent requirement. Here, we designed and prepared a porous polytetrafluoroethylene (PTFE)/C composite foam derived from PTFE/glutaraldehyde‐crosslinked poly(vinyl formal) foam via a method of low‐temperature in situ carbonization by the combination of sintering in nitrogen atmosphere and oxygen atmosphere. The as‐prepared porous PTFE/C composite foam had an interconnected macropore structure and wettability of superhydrophobicity. Meanwhile, the porous skeleton of the PTFE/C composite foam showed a skin–core microstructure with the functional skin layer of PTFE continuous phase and the support core of PTFE and carbon in situ composite phase. The PTFE functional layer was anchored to the support composite layer in a root‐like branching, which endows the porous PTFE/C composite foam with an extremely durable performance. In gravity‐driven oil–water separation, the porous PTFE/C composite foam achieved considerable oil flux (from 27 174 to 73 242 L h−1 m−2) and purity (as high as 99.83 wt%). Meanwhile, the porous PTFE/C composite foam presented resistance to strong acids, strong alkalis, chemical solvents and friction. Even after it had been mechanically damaged, the superhydrophobic properties of the foam were not degraded. The as‐prepared porous PTFE/C composite foam showed great potential in all kinds of harsh environments. © 2021 Society of Industrial Chemistry.

Design and preparation of polytetrafluoroethylene/carbon (PTFE/C) composite membrane‐equivalent foam for gravity‐driven emulsion separation

“…Subsequently, LTISC sintering was performed to obtain a porous PTFE/C composite MEF. 48 The bubble pore created by mechanical stirring and the icetemplated pore generated by freeze-casting play the roles of the cavity of size R and the pore neck of size r, respectively. Here, the bubble pores serve as the cavities of the PTFE/C composite MEF, while the ice-templated pores function as equivalent membrane pores that interconnect all the cavities.…”

“…47 To address this limitation, a porous PTFE/carbon (PTFE/C) composite foam with a one-level microporous structure was prepared in our previous work. 48 Porous PTFE/C composite foam was derived from the PTFE/glutaraldehyde crosslinked polyvinyl formal (PVFG) composite foam green body via a method of low-temperature in situ carbonization (LTISC) and exhibited significant oil flux and purity, along with exceptional resistance and stability. Unfortunately, its larger pore size hindered its effectiveness in separating emulsified oil-water mixtures.…”

About 3D Printability of Thermoplastic Collagen for Biomedical Applications

“…The boiling point of water is 100 °C at 1 atm, and above this value the water evaporates and water loss occurs during extrusion. On the other hand, a high water content can lead to a loss of the most important properties of collagen, such as mechanical properties, osteoconductivity, and biodegradability [ 20 ]. In the present work, a water content of 73% and an extrusion temperature of 90 °C were found to be optimal for printing TC.…”

Amphiphobic, Thermostable, and Stretchable PTFE Nanofibrous Membranes with Breathable and Chemical-Resistant Performances for Protective Applications

“…5,6 For hydrophobic waterproof and breathable membranes, the membrane materials are required to have a hydrophobic surface to provide water resistance, 7,8 a small interconnected pore structure, and high porosity inside the fibers to provide moisture permeability. 9,10 Generally speaking, PTFE waterproof and breathable membranes are widely used in the textile industry, 11−13 filtration media, 14,15 electronics, 16,17 electrical appliances, 18 and healthcare 19,20 due to their excellent chemical resistance, low surface energy, strong hydrophobicity, and thermal stability. 21−25 At present, the preparation methods of WBM mainly include melting extrusion, biaxial stretching, phase separation, flash evaporation, and electrostatic spinning (ES) methods.…”

“…Waterproof and breathable fabrics provide comfort and safety to textiles, which can effectively block the penetration of liquids, while quickly expelling evaporated sweat from the body, making them a promising smart textile . Currently, the most widely used WBM on the market are hydrophobic PTFE microporous membranes , and hydrophilic thermoplastic polyurethane (TPU) nonporous membranes. , For hydrophobic waterproof and breathable membranes, the membrane materials are required to have a hydrophobic surface to provide water resistance, , a small interconnected pore structure, and high porosity inside the fibers to provide moisture permeability. , Generally speaking, PTFE waterproof and breathable membranes are widely used in the textile industry, − filtration media, , electronics, , electrical appliances, and healthcare , due to their excellent chemical resistance, low surface energy, strong hydrophobicity, and thermal stability. − At present, the preparation methods of WBM mainly include melting extrusion, biaxial stretching, phase separation, flash evaporation, and electrostatic spinning (ES) methods. , Small pore size, high porosity, a high specific surface area, and customizable surface shape are characteristics of the fibrous membranes created by electrospinning. − While in the configuration of spinning solution of conventional electrospinning, significant amounts of tetrahydrofuran, formic acid, N , N -dimethyl­formamide (DMF), N , N -dimethyl­acetamide (DMAc), and other toxic solvents are consumed, , which will not only cause problems with air pollution and water pollution but also obstruct the large-scale production of WBM by electrospinning . The lingering hazardous chemicals can also damage organs and trigger skin allergies. , Therefore, it is crucial to design a green smart solvent WBM that is harmless to the environment. − …”