Fabrication Of Micro/nanostructure Arrays By Colloidal Lithography And Their Applications

Micro/nanostructure array is the combination of nanostructure,microstructure and ordered array structure,which is an important basis for the research of next generation devices.The properties of micro/nanostructure arrays include large specific surface area and high activity of nanostructure,good stability of microstructure and coupling and synergy effect among the elements of ordered array structure.The fabrication of large area micro/nanostructure arrays,the control of morphology and size,and the correlation between performance and structure parameters have become the research hotspots in the field of novel surface interface functional materials.Nowadays,both the "top-down" approach and the "bottom-up" approach have their own technical limitations in the fabrication of micro/nanostructure arrays.As a result,it is necessary to further research and develop the fabrication methods and mechanisms of micro/nanostructure arrays and then further study the influence of structure on surface properties and control mechanism in order to promote the research and development of new surface interface functional materials.In this dissertation,a series of research work has been carried out including the fabrication methods of micro/nanostructure arrays and the mechanism of tunable surface properties.The main contents and results are as follows:1.A hexagonally packed micro/nanostructure array was fabricated on polymer substrate by a combination of colloidal spheres arrays templates and oxygen plasma etching technology.This method is called colloidal lithography.The array structure has typical micro/nano grading characteristics,and the surface of the conical column array is covered with nanogrooves.The wettability properties of the micro/nanostructure array were studied.The results show that after modification by perfluorosilane the surface of the micro/nanostructure array exhibits robust superhydrophobicity and self-cleaning.The maximum static contact angle of the surface is close to 160°.In addition,a device with excellent load capacity was fabricated by using PMMA sheets with both superhydrophobic sides.The load capacity test showed that the superhydrophobic surface can increase load capacity by 89%.2.The micro/nanostructure arrays with different aspect ratios and morphological characteristics can be prepared by changing the colloidal sphere masks(PS microspheres or SiO2 microspheres)and etching conditions.The relationship between the surface wettability and the structure characteristics(such as length-diameter ratio,top morphology,etc.)was studied.The results show that the surface is superhydrophobic with different adhesives to water droplets,which shows the regulation of structure on the adhesion.Based on this characteristic,we realized the non polluting and lossless transportation of trace water droplets.3.The compatibility of various techniques in the fabrication of micro/nanostructure arrays was studied,and the multilevel structure arrays were obtained.Based on MEMS technology,a soft lithography was established.The microcolumn arrays with different top morphologies were prepared through adjusting curing conditions.The multilevel micro/nanostructure array was fabricated through combining soft lithography,colloidal lithography and etching process.The surface wettability of the multiscale micro/nanostructure array shows that the superhydrophobic surfaces with different adhesion can be obtained by adjusting the structure and morphology of the arrays,which provides a technical way to control the adhesion of the superhydrophobic surfaces.4.A flexible SERS substrate with Ag micro/nanostructure array was fabricated on the surface of ion exchange membrane(Nafion)by colloidal lithography combined with reactive ion etching and in situ chemical reduction.The flexible SERS substrate can be bent and tailored easily with strong toughness.It also shows excellent SERS sensitivity and repeatability.The detection limit of R6G and malachite green molecule is as low as 1×10-11 M and 1×10-10 M respectively.This research extends the application of micro/nanostructure arrays in the field of SERS detection.