Fabrication And Applications Of Micropatterned Surfaces

Technologies of fabricating micro-or nanopatterns have been the center in thematerial science and technology, and exhibit great significance in theory research andpractical applications. As the development of science and technology, the researchcontents and applied range of the micro-or nanopatterns are broadening, includingmicroelectronics, information store devices, micro-/nano-electromechanical systems,sensors, micro-/nano-fluidics, biological or medical interfaces, optical or photonicmaterials etc. To date, many methods have been used to fabricate micro-or nanopatterns,such as photolithography, electron beam etching, nanoimprinting, scanning probelithography, microcontact printing, block copolymer lithography etc. Each of thesetechniques shows their own advantages and shortages in surface patterning according tothe precision, repetition, productivity, cost and output. Recently,2D,3D micro-ornanopatterns have been prepared by selective evaporation, deposition, etching andimpringting using colloidal crystals as masks, we call them colloidal lithography.Colloidal lithography is deemed to a technology of fabricating micro-or nanopatternswhich is versatile, low energy cost, high output. This technology not only pushes thefield of microfabrication progress, but also promotes physics, chemistry, biologicalscience and the integration of them. In this thesis, we fabricate the micro-ornanopatterns by colloidal lithography, and make them functionalization andintelligentialize by rational design, optimization of nanostructures, and chemicalmodification.In chapter2, multifunctional antireflective surfaces have been prepared bycolloidal lithography. At first, we have prepare high aspect ration silicon nanotip arrays(up to12) by combination of colloidal lithography and metal catalytic etching silicon, and such nanotip arrays can effectively suppress the reflection of light from ultravioletto mid-infrared region. After modified by fluorosilane, the silicon nanotip arrays exhibitexcellent superhydrophobic properties. Besides, silica nanocone arrays have beenprepared by colloidal lithography on the fused silica substrates and convex lens, andsuch nanocone arrays can used as antifogging, antireflective surfaces in visible lightregion and antireflective surfaces in the near-infrared region. Moreover, we havestudied influences of the nanocone morphologies on the performances of antireflection,and demonstrated the influences by theory simulation. At last, we have fabricated whitelight organic emitting devices using the antireflective surfaces of visible light region assubstrates, and the efficiency of the device is improved about1.4fold.In chapter3, optical sensors based on micropatterned surfaces have been prepared.Firstly, we have been prepared polystyrene (PS) microsphere/Au half-shell hybridnanopatterns. The nanopatterns possess properties of surface plasmon resonance, andexhibit full colors by changing the experimental conditions. The properties of surfaceplasmon resonance are very sensitive to the refractive index change of externalenvironment. Therefore, they can be used as label-free, in-situ sensors to detect bovineserum albumin. In addition, we have been fabricated silicon/poly (hydroxyethylmethacrylate)(PHEMA) composite nanopost arrays by combination of colloidallithography and surface-initiated atom-transfer radical polymerization. Such compositenanopost arrays exhibit photonic stop bands, and the photonic properties can be tunedby controlling the time of polymerization. We have been also fabricated patternedcomposite nanopost arrays by photolithography. Due to the water vapor sensitivity ofPHEMA brush, such composite nanopost arrays can be used as sensors to detect watervapor, and the sensors exhibit fast rate of detection and excellent repeatability.In chapter4, we have prepared polymer brush nanopatterns over large areas bycombination of colloidal lithography and surface-initiated atom-transfer radicalpolymerization, and the polymer brush nanopatterns have potentials in the fields of protein/DNA arrays, cell patterning and microreactors. The polymer nanopatterns havebeen prepared by two methods. One is that initiators are patterned by colloidallithography before preparation of polymer brush. The other is that the polymer brushpatterns are fabricated by colloidal lithography after preparation of polymer brush films.By using colloidal lithography, the polymer brush nanopatterns over large areas havebeen prepared, and the feature sizes of the patterns have been tuned from tens ofnanometers to several micrometers. Some complicated nanstructures, such as nanostriparrays and elliptical nanoring arrays have been fabricated by colloidal lithographyimprinting and colloidal lithography dewetting respectively. The chemistry of thepolymer brush nanopatterns have been tuned by changing the monomers ormodification after polymerization. In addition, hierarchical nanopatterns have beenfabricated by using photolithography. Nanopatterns of biomoleules have been preparedby covalently conjugating proteins or DNA on the PHEMA brush nanopatterns, andexhibit good biological activity. Hierarchical fibronectin nanopatterns can be used topatterning osteoblast and control the orientation of cells. Besides, polymer/Aunanoparticles hybrid nanopatterns have been prepared by host-guest interaction betweendimethylamino group of poly (2-(dimethyl amino) ethyl methacrylate)(PDMAEMA)brush and-cyclodextrin. Optical properties of the hybrid nanopatterns can be tuned bychanging etching conditions. At last, PDMAEMA brush nanopatterns have been used asa microreactor to prepare polymer/silica nanoparticle nanopatterns by biomineralization.