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Waterproof and breathable materials can prevent water droplets from penetrating while allowing water vapor to diffuse, and are widely used in clothing, sports equipment, healthcare products and other fields.
Traditional polytetrafluoroethylene (PTFE) microporous membranes have problems such as poor elasticity and harmful to the environment and organisms.
Polyurethane (PU) is regarded as a substitute for PTFE due to its excellent elasticity and environmental prospects.
Chemical modification and electrospinning: Using polyurethane (PU) emulsion as the polymer matrix, adding 4,4'-methylenebisphenyl isocyanate (4,4'-MDI) and 3-aminopropyltriethoxysilane (APTES) for chemical modification, PU nanofiber membrane was prepared by electrospinning.
Hydrothermal assisted sol-gel method: The PU nanofiber membrane obtained by electrospinning was immersed in the silica (SiO2) preparation solution, and the SiO2 particles were firmly bound to the surface of the PU nanofiber through hydrolysis reaction.
Material characterization: The surface morphology of the nanofiber membrane was observed using a scanning electron microscope (SEM), and performance indicators such as hydrophobicity (contact angle), mechanical properties (tensile stress-strain curve), air permeability and water repellency (hydrostatic pressure) were tested.
Environmentally friendly material development: An environmentally friendly chemical modification method was proposed to avoid the use of fluoride and use silane for surface modification to reduce the impact on the environment.
Preparation process: Combining emulsion electrospinning technology and hydrothermal assisted sol-gel process, PU/SiO2 nanofiber membrane with rough surface and low surface energy was innovatively prepared, providing new ideas for the development of new high-performance materials.
Excellent performance indicators: high hydrostatic pressure, good air permeability, high water vapor permeability, excellent hydrophobicity (contact angle 154°) and high mechanical strength (tensile strength 5.3 MPa, elongation at break 198%).
Durability: The SiO2 particles on the surface of the nanofiber membrane are firmly bonded to the PU matrix. After 24 hours of ultrasonic cleaning, the mass loss rate of SiO2 is only 9.72%, showing good durability.
Figure 1: Schematic diagram showing the preparation process of super hydrophobic and durable PU/SiO2 nanofiber membrane.
Figure 2: SEM images of PU/4,4'-MDI-X nanofiber membranes at different 4,4'-MDI concentrations are shown.
Figure 3: SEM images of PU/4,4'-MDI-0.4/APTES-Y nanofibrous membranes at different APTES concentrations are shown.
Figure 4: SEM images of the fiber membranes at different treatment times are shown, as well as the waterproofing mechanism of the fiber membranes proposed based on the Cassie-Baxter equation of state.
Figure 5: SEM images of the fiber membranes at different ultrasonic cleaning times are shown, as well as the corresponding contact angle and TGA changes.
The preparation and properties of a new type of superhydrophobic and durable polyurethane/silica (PU/SiO2) nanofibrous membrane were studied in this paper. The nanofibrous membranes obtained by chemically treating PU emulsion and converting it into nanofibers and then forming SiO2 particles on the surface of nanofibers through a hydrothermal-assisted sol-gel process exhibited excellent properties, including high hydrostatic pressure, good air permeability, high water vapor permeability, excellent hydrophobicity, and high mechanical strength.
Electrospinning Nanofibers Article Source:
https://pubs.acs.org/doi/10.1021/acsanm.2c02017
