Superhydrophobic Cotton Fabrics Through Atmospheric Plasma Treatment For Applications In Oil-water Separation

Superhydrophobic materials could be excellent candidates in the application of self-cleaning,oil-water separation,anti-icing and marine drag reduction due to its special wettability.Many methods of constructing superhydrophobic surfaces have been reported with more in-depth researches on superhydrophobic surface.Among them,atmospheric pressure plasma jet technology as a late-model of plasma technology has a lot of advantages such as simple operation,low energy consumption,low cost and high security.Superhydrophobic cotton was fabricated in one-step way via atmospheric pressure plasma jet technology with oxygen used as ionized gas,hexamethyldisiloxane（HMDSO）and octamethylcyclotetrasiloxane（D4）used as precursors.The application of as-prepared cotton in the oil-water separation was explored as well.The main content of this thesis was organized as follows:（1）HMDSO was used as precursor,the surface morphology and hydrophobic properties of the modified fabric were investigated with respect to duty cycle time,precursor flow rate and types and flow rate of ionization gas.The results show that when the cycle time is 60%,the precursor flow rate is 15g/h,and the ionized gas flow rate is 1500L/h,the modified fabric can obtain excellent superhydrophobic property,and the modified fabric is under oxygen plasma condition.The CA values of O₂plasma-treated cotton is significantly higher than N₂ plasma-treated cotton.（2）D4 was used as precursor,the surface morphology and hydrophobic properties of the modified fabric were investigated by duty cycle time,precursor flow rate and ionized gas flow rate,and hydrophobic properties of D4 modified cotton fabrics were also compared with HMDSO modified cotton.The results show that stability and CA values of the superhydrophobic HMDSO modified cotton fabric are more excellent than D4 modified cotton under the same operation parameters.（3）The surface morphology and chemical composition of the fabric before and after modification were analyzed by infrared absorption spectroscopy,scanning electron microscopy and EDS.It was found that a film formed by nanoparticle deposition was deposited on the surface of cotton fiber,and the infrared absorption spectrum displayed that chemical bonds such as Si-O-Si and Si-CH₃ are grafted onto the surface of the cotton fiber,and elemental analysis indicates that the silicon element is distributed evenly throughout the surface of the fiber.（4）The wearing properties of cotton fabric modified by the two precursors and untreated cotton was tested,and it was found that the treatment hardly affected the air permeability and tensile strength of the cotton fabric.it was found that the CA values did not decrease significantly after the modified fabric was stored in the open environment for three months,and the degree of contact angle drop after washing was within an acceptable range.（5）Finally,the application of superhydrophobic cotton on oil-water separation was also explored.The results show that the separation efficiency for different oil-water mixtures by modified cotton was very high,and the efficiency of seed oil-water mixture after ten separation times was still up to 95%,and it also resistant to harsh conditions such as strong acid,alkali and high temperature.