Research On Microemulsion Preparation And Membrane Properties Of Fluorinated Polyacrylate

The fluorinated polyacrylate has good film forming ability and substrate adhesive property as polyacrylate, as well it possess excellent chemical stability, weather resistance and self-cleaning by adding fluoride, and has been used widely in car, microelectronic, and functional coating. Traditional fluorinated polyacrylate preparation requiring a lot of solvent and biological accumulation of long fluorocarbon chain decomposition limit its application. With new environmental method and short fluorocarbon, fluorinated polyacrylate preparation has important significance.In this paper, polymerizable emulsifier MPEGMA was prepared, and then reverse microemulsion system was built and initiated to get fluorinated polyacrylate membrane. The main contents as follow:Polymerizable macromolecular MPEGMA was prepared by esterification of methacrylic acid(MAA) and methoxy polyethylene glycol(MPEG1000) with p-toluene sulfonic acid as catalyst, phenothiazine as inhibitor, and toluene as dehydrant. The main parameters were investigated with the esterification rate as measurement index. The best process parameters were optimized by orthogonal experiment. Using FTIR characterized the product.Inverse microemulsion system was constructed with MPEGMA as polymerizable emulsifier, MMA and HFBA as oil phase, and 0.02mol/L KCl solution as water phase. The stability of system was studied by electrical conductivity and visual method, and the appropriate scope of microemulsion system components was determined. The pseudo ternary diagram of microemulsion system was made.Microemulsion polymerization was prepared with AIBN as intiator and reaction temperature 70℃. The best fluorinated polyacrylate film forming time was ensured by investigation of polymerization viscosity. The effect of HFBA on copolymer membrane was studied by FTIR, TG, DSC and solvent resistance test. The copolymer membrane surface properties were characterized by surface contact angle tester, XRD, SEM and filtration experiment. The effect of microemulsion composition, membrane forming method and processing mode on hydrophobicity was investigated.The result showed that: the optimal condition of esterification included n(MAA)/n(MPEG)=3, the esterification temperature was 120℃, esterification time was 8h, catalyst weight was 2.5% of the weight of monomers, dehydrant dosage was 30% of the weight of monomers, and inhibitor dosage was 2.5% of the weight of methyl acrylic acid. Under the optimal condition the esterification rate was 92.7%; and the controllable range of MPEGMA/MMA-HFBA/KCl solution was narrow.HFBA can improve the hydrophobicity and heat resistance of membrane, the water contact angle can be 110°,but continuing to increase HFBA did not improve hydrophobicity. However, adding MPEGMA weakened hydrophobicity. The surface water contact angle of the front and back appeared differently, the maximum gap was 15°. At the same time, the membrane forming method and post-treatment can change membrane surface chemical composition to impact the property. Different water content of system caused different surface morphology, and the micro surface roughness was conducive to increasing hydrophobicity; and the self-cleaning was excellent.