Fabrication,Properties And Application Of Organic And Organic-inorganic Hybrid Superhydrophilic Coating

When a water droplet falls onto materials' surface,it will spread completely and quickly to form a thin film,and the contact angle is nearly zero,and these materials can be thought to be superhydrophilic.The superhydrophilic materials were not only widely used in the fields of self-cleaning,anti-fogging,anti-fouling and oil-water separation,but also exhibited the potential application in heat transfer,microfluidic control,biomolecular immobilization,accumulation of rainwater and drag reduction.Currently,most fabrication methods involve expensive instruments or complex processes,which are difficult to be used in large scale production.While the micro-nano structure,significant for the superhydrophilic coating films,is easy to be destroyed by external forces,resulting in loss of the superhydrophilicity.In addition,short service life and vulnerable to external factors such as light and temperature,leading to not meeting the requirement of long-term use.In this work,a facile approach was firstly proposed to prepare UV-curable super-hydrophilic polyacrylate coating film that was chemically grafted on the surface of glass substrate and studied its application in the field of antifogging.Then a facile approach was put forward to designing the robust organic-inorganic hybrid superhydrophilic coating films under UV radiation.Finally,superhydrophilic and underwater superoleophobic thiol-ene/silica hybrid decorated fabrics were fabricated via one-step vapor-liquid interfacial reaction,and discussed its application in oil-water separation.The research contents and results are listed as following:Firstly,we first used a piranha solution to treat glass substrate so as to increase the number of hydroxyl groups,and then the substrate was further modified by ?-methacryloxypropyltrimethoxysilane(KH570)to introduce C=C double bond.The superhydrophilic polyacrylate coating films chemically grafted onto glass substrate was prepared with 2-methacrylatoethyl trimethyl ammonium chloride(DMC)and trimethylolpropane triacrylate(TMPTA)as hydrophilic monomer and crosslinker,respectively,by UV-initiated polymerization.A UV-curable super-hydrophilic polyacrylate coating film chemically grafted onto the KH570-modified glass substrate successfully was characterized by Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS).When the mass ratio of DMC and TMPTA was 8/2,the water contact angle(WCA)reached the lowest value at nearly zero within 2.5 s.The UV-curable super-hydrophilic polyacrylate coating film also exhibited excellent transmission and antifogging property.Secondly,ene-terminated hydrophilic oligomer(ETHO)was synthesized by thiol-ene reaction between DL-dithiothreitol(DTT)and poly(ethylene glycol)dimethacrylate(PEGDMA)with n-butylamine as catalyst,and the structure was confirmed by FT-IR,proton nuclear magnetic resonance(1H NMR)spectroscopy,carbon nuclear magnetic resonance(13C NMR)spectroscopy and Gel permeation chromatography(GPC).Then the superhydrophilic organic-inorganic hybrid coating films were fabricated by spraying method with ETHO and HMSNs as main raw materials,TMPTA as cross-linking agent,and Darocur 1173 as photoinitiator under UV irradiation.When the mass ratio of HMSNs/ETHO reached to 0.75,the coating films could achieve superhydrophilic state within 0.24 s.The superhydrophilic hybrid coating films also possesed good flexibility,impact resistance and adherence to substrates.Besides,the coating films could maintain superhydrophilicity under the condition of abrasion,acid or high-temperature,and exhibited widely environmental suitability.Finally,we report one-step vapor-liquid interfacial reaction method to fabricate superhydrophilic and underwater superoleophobic fabrics for oil-water separation.It is based on the sol-gel reaction of tetraethyl orthosilicate(TEOS)to generate silica and thiol-ene reaction between PEGDMA and trimethylolpropane tris(3-mercaptopropionate)(TTMP)to form crosslinked hydrophilic polymer under the catalysis of butylamine/ammonia on polyester fabrics.The chemical structure of the surfaces on the as-fabricated fabrics was confirmed by FT-IR and X-ray photoelectron spectroscopy(XPS),and the obvious micro-nano morphology and roughness were observed with SEM and atomic force microscope(AFM).The WCA attained 0 o in 0.36 s,and the underwater oil contact angle(UOCA)reached up to 160 o.Importantly,the as-prepared fabrics exhibited high separation efficiency at 99.5% and fast water flux above 71600 Lm-2h-1 in oil-water separation,which changed little under different temperatures.Furthermore,the thiol-ene/silica hybrid decorated fabric could support up to 2.97 kPa of oil pressure,showing the outstanding separation capability.Additionally,the as-prepared fabrics also possessed excellent recyclability.