Fabrication And Test Of Superhydrophobic Surfaces Modified By Silicon Materials

Superhydrophobic microchannels have not only the advantages of traditional hydrophilic or hydrophobic microchannels in process intensification and safety control of chemical engineering,but also the unique superiority in self-cleaning,improving heat transfer coefficient and reducing fluid resistance,which have drawn extensively attention of researchers over the last decade.At present,the preparation of superhydrophobic materials has some deficiencies,such as tedious process,high cost and none environmentally friendly.It is much more difficult to prepare transparent superhydrophobic microchannel with stable wettability.This thesis investigates the preparations of superhydrophobic surfaces based on different experimental process and aims at fabricating transparent and robust superhydrophobic surface for applying to hydrophobic microchannel reactor.Firstly,the rough structures on the glass surface were constructed by sol-gel method of using methyltrimethoxysilane as the precursor.After modifying by trimethylchlorosilane(TMCS),the as-prepared coatings exhibit hydrophobic properties.The effects of TMCS dosage,modification time,different pH conditions,ammonia concentration and gel time on the contact angle of glass substrate were discussed.Subsequently,In order to improve the hydrophobicity,monodispersed single-scale and dual-scale patchy silica nanoparticles have been prepared,and further modified by TMCS.The superhydrophobic and transparent coatings on the various types of substrates are obtained by a simple drop-casting procedure.In this process,the effect of roughness on wettability was discussed.Then theoretical model of water droplet on the hydrophobic rough surface was discussed based on the experiment results,Wenzel and Cassie-Baxter models.Polydimethylsiloxane(PDMS)was used as binding agent to improve mechanical adhesiveness of the coatings by two kinds of experimental processes.In the first process,PDMS was used as low surface energy materials and curing materials,and hydrophobic SNSs constructed roughness and provided low surface energy.The hydrophobic coatings on the glass and filter paper surface were prepared by spin and dip coating process,respectively.The influence of SNSs dosage on the contact Angle and microstructure of the coating was discussed.In the second process,thin PDMS film was used as the substrate.The transferable and flexible superhydrophobic film was prepared by impressing method.Above researches lay the foundation for the subsequent application in the microchannel.