Preparation And Photoresponsive Wettability Study Of POSS Based Fluorinated Azobenzene Polymers

Environmental response surface with reversible wetting behavior has a wide application prospect in microfluidic devices, intelligent film, controlled drug release,sensors and turbulence research and so on. Recently, the photo-switchable water wettability on surfaces has been studied, but the study on photo-switchable oil wettability is very few. Long fluorocarbon chains(-CnF2n+1,n ≥ 8) with low surface free energy are suitable for constructing the switchable oil wettability surface.However, long fluorocarbon chains are difficult to be biodegradable, and harmful to the environment and human health.Therefore, this study intend to use short fluorocarbon chains(perfluorobutyl,perfluorohexyl) and fluoroether chain instead of long fluorocarbon chain(perfluorooctyl) for preparing fluorinated azobenzene monomers. Then, polyhedral oligomeric silsesquioxane(POSS) and the fluorinated azobenzene monomers were copolymerized to afford a series of POSS-based fluorinnated azobenzene-containing polymers. It was found that the thermal stabilities of the POSS-based polymers were enhanced and the wettabilities of the POSS-based polymer coated fabrics were improved, comparing to those of the polymer without POSS. Under the UV/visible light irradiation, the POSS-based polymer coated fabrics achieve reversible change in wettability.The main work is described as follows:Acrylate monomers 7a ~ c containing perfluoroalkyl chain and 12 containing perfluoropolyether chain were prepared through the Ullmann reaction, diazo coupling reaction and esterification reaction by using nonafluorobutyl iodide,tridecafluorohexyliodide,heptadecafluorooctyliodideandhexafluoro-1,2-epoxypropanetrimer(thpf)asthestartingmaterial,respectively.thenthefluorinatedmonomerswerecopolymerizedwithmmaandov-poss,aibnasinitiator,aseriesofpossbasedperfluoroalkylazobenzenepolymers(p1~p16)andperfluoroethercontainingazobenzenepolymers(p17~p20)withdifferentposscontentsweresuccessfullypreparedviaradicalpolymerizationinthf.theresultingpolymerswerecharacterizedbynmr,ir,uv,gpcandtgaanalyses.surfacemorphologyofthecottonfabriccoatedwiththepolymerwasobservedbyfe-sem.thestaticcontactangleofwaterandsaladoilweremeasuredbythecontactanglemeasurement.themaximumwaterandsaladoilcontactangleonthes1~s4reaches156°and143°,themaximumwaterandsaladoilcontactangleonthes5~s8reaches153°and140°,respectively.afterirradiatedwithuvlightfor10 minutes,themaximumwaterandsaladoilcontactanglereductionons1~s4was21°and30°,andthatons5~s8was19°and22°,respectively.thens1~s8wereirradiatedwithvisiblelightfor1h,andthewaterandsaladoilcontactanglesalmostrecoveredtotheinitiallevel.afterfourcyclesofuv-visiblelightirradiation,thecoatedfabricswerestillphotoresponsivewhichindicatedthefatigueresistanceofthepolymers.