Preparation And Properties Of Multifunctional Antifogging Coatings Based On Polyelectrolytes

Due to changes in temperature and humidity during use,fog/frost formation on transparent materials such as solar goggles,goggles,windshields,etc.significantly reduce the transparency,thus decreasing their operational performance.In addition,food packaging and medical devices such as endoscopes are not only prone to fogging,but also have the risk of bacterial infections during use.Therefore,preparation of the multifunctional surfaces with antifogging,frost-resisting and anti-bacterial properties is of important significance.In this dissertation,antifogging/frost-resisting and antifogging/antibacterial coatings based on the polyelectrolytes are focused.Amphiphilic block copolymers of cationic,zwitterionic or anionic poly((2-(dimethylamino)ethyl methacrylate)-co-2,2,2-trifluoroethyl methacrylate)-bpolyelectrolytes were synthesized via reversible addition-fragmentation chain transfer(RAFT)polymerization,then the coatings were developed from the copolymers with a small amount of ethylene glycol dimethacrylate via UV-curing.The effects of polyelectrolyte types on antifogging/frost-resisting properties were studied.It was suggested that the cationic and zwitterionic polyelectrolyte-based coatings exhibited superior antifogging properties,whereas the anionic polyelectrolyte-based coating demonstrated a better frost-resisting behavior.Water molecule activities in the amphiphilic coatings were analyzed by differential scanning calorimetry,Raman spectroscopy and low field nuclear magnetic resonance.The results showed that the cationic and zwitterionic polyelectrolyte-based coatings exhibited stronger polymer-water interactions dominated by strong hydrogen bonds and held more bound water content with shorter transverse spin-spin relaxation time than the anionic coating.Electrostatic interactions between anionic polyelectrolyte and poly((2-(dimethylamino)ethyl methacrylate)units in the copolymer weaken the polymer-water interaction relatively,leading to a compromise in the antifogging performance and an enhancement of frost-resisting ability of the coatings.Cationic copolymer containing quaternary ammonium salt of polyhedral oligomericsilsesquioxane-poly(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylbutan aminium bromide-co-2-aminoethyl methacrylate hydrochloride)(PQA)was synthesized by RAFT polymerization using polyhedral oligomeric silsesquioxane modified 4-cyanopentanoicacid dithiobenzoate as the chain transfer agent.Random copolymer of poly(N-hydroxyethyl acrylamide-co-glycidyl methacrylate)(PHG)was also synthesized by conventional free radical polymerization.The two synthetic copolymers were coated step by step with 1,3,5-triformylbenzene as the cross-linking agent to prepare a bifunctional coating with antifogging and antibacterial properties.It could be found in the antifogging and antibacterial tests that compared with monocomponent and blend coatings,the prepared dual-layered coating with PQA as the bottom layer and PHG as the outer layer not only had excellent antifogging performance,but also prensented good bactericidal and bacterial anti-adhesion properties.