The Construction Of Complex Two-dimensional Structure

Surface patterning is a method that has a long history and can enrich the surface properties and functions of materials.With the advancement of new standards for high-speed,high-efficiency and energy-saving materials,the demand for micro/nano-scale patterning is increasing.Traditional micro/nano-scale patterning mostly depends on expensive substrate materials and rare large-scale processing equipment,with a higher cost and complicated process.Therefore,the development of a new,simple,universal patterning,which can achieve fine controllable and periodic continuous patterning on micro-nano scale two-dimensional surface,is of great significance to promote the widespread application of patterning technology.In the thesis,a new method to achieve patterning on the micro/nano scale two-dimensional surface is studied from two respects.First,a“bottom-up”method is employed to explore the preparation of patterned organic materials with crystalline polymers periodically and uniformly distributed in the two-dimensional plane from the perspective of chemical molecular structure design;second,based on the prepared patterned materials,the conditions for patterning on a two-dimensional surface were studied tentatively.?1?Construction of a two-dimensional surface patterned material:we have designed and synthesized a new type of trialdehyde indenyl monomer?compound 9?.It is a two-dimensional planar structure containing C₃ symmetrical aldehyde groups molecule axially grafted with a short chain with six alkynyl groups at its end.The six short chains can be symmetrically distributed on the upper and lower sides of the molecular plane as active sites.Through the efficient“Click”reaction,m PEG_1K-Tr-CHO,m PEG_2K-Tr-CHO,m PEG_4K-Tr-CHO patterned precursors have been abtained by,introducing crystalline polymer polyethylene glycol?PEG?of different molecular weights.Finally,solvothermal method?acetic acid as catlyst?was used to construct a two-dimensional surface patterned material,m PEG_1K-Tr-COF and m PEG_2K-Tr-COF.Acoording to the spectras of Fourier Transformed infrared spectroscopy a newly generated absorption peak appeared at 1631 cm^-1,which proves there exsited the imine bond and that we successfully prepared a patterned organic material with crystalline polymer uniformly distributed periodically in a two-dimensional plane.?2?Exploration of micro/nano-scale two-dimensional surface patterning conditions:According to the periodic distribution of crystalline polymers in the two-dimensional framework of imine bonds,and the special restricted environment in the two-dimensional plane,we studied impact of different solvents,different molecular weights of the polymers on the two-dimensional pattern of micro/nano scale.In a good solvent?dichloromethane?,m PEG_1K-Tr-COF and m PEG_2K-Tr-COF formed a large-scale square crystal and hexagonal structure crystal pattern stacked layer by layer.When the molecular weight of the grafted polymer PEG increased from 1000 g·mol^-1 to 2000 g·mol^-1,the size of the hexagonal crystal increased from 45 nm to 138 nm.However,the observed special crystal patterns were not monolayer.When trying to reduce the sample concentration,although the monodispersed crystals ware obtained as expected,there ware fewer samples that could be observed,and no crystals with a special structure ware formed.When AFM was used to characterize the patterned morphology,compared with direct drop sample,crystals in sample dispersed more uniform by employing the spin coating method,and the measured sample height is much higher than the theoretical monolayer thickness,which is consistent with the TEM results;however,because of the lack of good sample preparation conditions and characterization accuracy,it is difficult to observe crystals with regular structure.When using a selective solvent?pentyl acetate?to study the patterning in a“self-seeding”manner:m PEG_1K-Tr-COF would form large-sized crystals with certain angles.While m PEG_2K-Tr-COF is similar to the situation in good solvent,where some stacked large-size square crystals are formed,but most of them are still in the form of random aggregates,which is mainly due to the insufficient crystallization conditions.Characterization results of Fourier Transformed infrared spectroscopy,TEM and AFM prove that we have successfully patterned on the micro/nano scale two-dimensional surface with a“bottom-up”method.Moreover,a new type of axial we prepared contains modified the two-dimensional planar organic material?Compound 9?has certain versatility and can be modified with various functions,which lays a significant research foundation for the realization of more complex and versatile two-dimensional surface patterning at the micro/nano scale.