Preparation Of Novel Photoinduced Reactive Hydrophilic/Hydrophobic Surfaces

Superhydrophobic surface based patterns have a wide range of potential applications in microarrays and microfluidics,anticorrosion,anti-icing,drag reduction,drug release,oil/water separation,printing,et.al.However,the common methods for creating superhydrophobic surface based patterns suffer from problems such as multistep process and poor flexibility.Photochemical method has many advantages,such as fast reaction,mild reaction conditions,easy to control and less side reaction.In this study,we fabricated a variety of reactive(super)hydrophobic surfaces(RSS)via photochemical method and utilized this surface reactivity to further realize surface functionalization and patterning.Besides,this photochemical method is applied to prepare paper chips with hydrophilic/hydrophobic channel.The detailed contents of the work are listed as follows:(1)Fabrication of RSS: Microporous poly(2-Hydroxyethyl methacrylate-co-ethylene dimethacrylate)(HEMA-EDMA)films are prepared by UV-initiated radical polymerization of a monomer/porogen mixture,then the obtained surfaces are modified to introduce disulfide bond onto the substrates.On this basis,we successfully fabricated four kinds of RSS including perfluorooctyldimethylchlorosilane(FOS)surface,perfluorodecanethiol(FDT)surface,didodecyl disulfide(Do D)surface and alkene/alkyne surface.The HEMA-EDMA films before and after modification are characterized by scanning electron microscope(SEM)and Raman spectrometer.(2)Functionalization and patterning on RSS: The high reactivity of disulfide based reactive(super)hydrophobic surfaces(DRSS)are utilized to realize the functionalization of DRSS by reacting with alkenes,alkynes and disulfides,mercaptans,epoxides and other functional groups.Considering the reversibility of DRSS,the modified disulfide surface can be modified again.In addition,patterns with a variety of different shapes on DRSS could easily be obtained by using different photomasks.In this case,a variety of fluorescent patterns on DRSS are obtained by local modification of fluorescent dyes and the smallest feature size of the produced patterns was 20 ?m.Also,hydrophilic/hydrophobic patterned surfaces are obtained by local modification of hydrophilic groups on DRSS.We then test the thermal stability and UV stability of the prepared four kinds of RSS,and find that the FDT surface exhibit good stability.(3)Application of RSS in paper chips: Different functional papers could be obtained through UV-initiated thiol-ene chemistry after treating paper with trichlorovinylsilane(TCVS).Besides,different patterns could be easily obtained by using different photomasks.Thus our method has the advantages of good controllability and high resolution.In addition,We also show the application of our method in the fabrication of paper chips with hydrophilic/hydrophobic channel,which could be utilized to detect urea and lactate.