The Study On The Bioinspired Pattened Surface Of The Photo-curing Coating And Their Application

Complex and self-organized surface patterns are everywhere in nature and biological system. Patterned surfaces are more attractive not only because they can bring people to the visual impact but also they can endow the living creatures some kinds of special talent, such as superhydrophobicity, self-cleaning effect, controlling adhesion and release, anti-reflection, light diffusion, to lower fluid resistance, absorption of infrarad and so on. Usually, there are two methods for fabricating patterned surfaces: top-down and bottom-up methods. The top-down strategies involving laser ablation, chemical etching, photolithography, lithopraphy, droplet method and imprinting method, have been developed quickly and widly used in commercial introductions. All these techniques demonstrate the ability to fabricate well-organized surface patterns and showing excellent functions. However, there are many disadvantages of these methods, such as multiple and complex fabricating steps, expensive equicpments used in the fabrication, be impossible to fabricate patterned surface with large area. Meanwhile, bottom-up strategy usually involved self-assembly and self-organization thechniques, and in biological systems, the samilar bottom-up strategies have been adopted for the hierarchical structuring of molecules to meter-scale biological organisms. The bottom-up method shows many advatanges in fabrication of surface patterns, such as facile fabrication steps even in one step, low cost and preparation of pattered surface in large area. However, there are many flaws of the patterned surface by these biological methods, more researches and improvements should be done to apply them in commercial productions. So, at presnt, to develop a facile method to fabricate patterned surface with large area is also a meaningfull challenge. In this thesis, we have developed a facile bottom-up approach for fabricating patterned surface on planar or non-planar substrates, based on UV-curable, reactive phase separation, surface self-assemblly and interface self-organization techniques. Large area patterned UV-curing coating with different morphologies were prepared, the wettability and light properties of the prepared patterned coating and their potential application in LEDs and solar cell encapsulation were studied. The details of research are as follows:(1) To present the “Surface self-assembly of fluorinated molecules/Interface self-organization of UV-curing resin coating” strategy to prepare patterned surface at the first time: The fluoride and thiol containing polyhedral oligomeric silsesquioxane(F2-POSS-SH6) were introduced into the muti functions acrylic monomers liquid coating, they can migrate onto the surface and self-assemble into top layer to decrease the interface energy between UV-curable liquid acrylate resin and air due to the low energy and phase separation properties of the fluorinated chains. Upon the exposure of UV light, thiol-ene click polymerization happens in the top layer, while conventional radical polymerization takes place in the bulk layer. The different shrinking rate of polymerization between top and bulk layer can cause compressive stress, resulting in the complex wrinkling patterns simultaneously. We have studied the self wrinkling mechanism of the bilayer acrylic coating in detailes. And different wrinkling coatings with different morphologies were prepared by changing the acrylic monomers. The hydrophobic properties of the self wrinkling patterned coating were also studied.(2) To extend the “Surface self-assembly of fluorinated molecules/Interface self-organization of UV-curing resin coating” strategy: A series of fluorinated copolymers were synthesized by copolymerization of olefin monomers and fluorinated acrylic monomers. We here investigated self-wrinkling surface of photo-curing systems which are comprised of the multi functions acrylic monomers and fluorinated copolymers. Fluorinated copolymers with low-surface energy can self-assemble at the air/acrylate interface to form the top layer of the photo-curing liquid resin. The mismatch of shrinkage caused by the photopolymerization between the top layer and bulk layer leads to formation of the wrinkling surface. Various factors including concentration of fluorinated polymer, photopolymerization kinetics and mechanical performance of the photo-curing systems to affect the morphology of the wrinkling surface were investigated systematically. We also studied the self-healing properties of the self wrinkling coating by water contact angle investegation.To prepare a series of self patterned UV-curing coating with different morphologies based on “Surface self-assembly of fluorinated molecules/Interface self-organization of UV-curing resin coating” strategy: We studied the effect of the patterns on the light properties of the curing coating, the results indicated that the patterned surfaces enhance the light transmittation and decrease the reflection of the curing coatings. The self patterned coating were used to encapsulate the commercial solar cells to investigated their effect on the external quantum efficiency, the result shows that the self patterned surface coating can enhace the external quantum efficiency of the solar cells.(3) We have developed a bottom-up approach for fabricating fluorinated copolymers micro lens arrays(MLAs) on planar or non-planar substrates, based on UV-curable, self-assembly of the fluorinated copolymers in the liquid arylic resin coating, reactive phase separation of the fluorinated copolymers in acrylic cross-linking systems and interface self-organization of the liquid fluorinated copolymers. The formation mechanism of the fluorinated copolymer micro lens arrays was stuied in details by controlling the the heat treated temperature, the C=C conversion, thickness of the UV-curing coating films, the structure of the fluorinated copolymers and the fluorescence labeling method. The size and the curvature of the self micro lens arrays were controlled by controlling the heat treated temperature and the thickness of the UV-curing coatings. We use this kind of self MLAs to encapsulate the integrated LEDs devices, and the effects of the self MLAs coating on the light extraction efficiency and light diffusion were studied.(4) To present a facile self-hemispherical encapsulation strategy for LED chip: We have synthesized silicone combining styrene-modified mercaptopropyl-polysilsesquioxane(St-POSS-SH) and poly silsesquioxane ladder of acrylic and phenethyl sulfide groups(LPSQ). The photo curing silicone resins(St-POSS-SH/LPSQ) were prepared by complex the St-POSS-SH and LPSQ at a fixed ratio. When the liquid St-POSS-SH/LPSQ droplet was adhered to the LED chip surface, lens was self formed by the surface tension, and the St-POSS-SH/LPSQ self lens encapsulation of the LED chip was obtained by exposing the liquid St-POSS-SH/LPSQ self lens to the UV light. We studied the effect of curvature of the self-organized lens on the light extraction effiency of the LED chip. And the self-hemispherical encapsulation can achieve about 33.5% enhancement in LEE of the LED chips.