Study On Organic Inorganic Composite One-dimensional Photonic Crystals Via Dip-coating Layer-by-layer Assembly

In recent years,organic inorganic composite one-dimensional photonic crystals(1D PCs)have received attention in the fields of colorimetric sensing,anti-counterfeiting,and energy utilization.Dip-coating layer-by-layer(Lb L)assembly has the advantages of environmental friendliness,simple operation,film thickness control,and suitable for multi-morph substrates to prepare 1D PCs.However,few material categories were introduced into the preparation of1D PCs with this method dip-coating,especially polymers with good film-forming properties,so it is limited to functional applications.The polymer nanoparticles were designed and prepared in this work,which have good water dispersibility and small average particle size.And with the help of polyelectrolyte solution,composite 1D PCs were constructed with the advantage of electrostatic interaction Lb L assembly between inorganic nano-oxides and the polymer.Meanwhile,film growth and optical properties of 1D PCs were also studied in order to provide a foundation for its application in the future.Polymethyl methacrylate(PMMA)nanoparticles were prepared by an improved microemulsion polymerization method,and studied the relation between the Zeta potential and particle size of PMMA surface under different p H values.The optimal PMMA with average nanoparticle size was 28.55 nm and the Zeta potential is-32.0 m V,which is stably dispersed in water.The average nano-particle size of Ti O₂ is 36.46 nm,and the Zeta potential is 41.6 m V.With the assistance of poly(styrene sulfonate)(PSS)and poly(diallyldimethyl ammonium chloride)(PDAC),(Ti O₂-PSS)_n and(PDAC-PMMA)_n were obtained to alternately assemble with the above-mentioned nanoparticles.And this work also studied the assembly rules of(Ti O₂-PSS)_n and(PDAC-PMMA)_n on the film thickness,refractive index and roughness of different cycle times n,and adjusted the film thickness in the range of26?138 nm and 30?310 nm respectively.Furthermore,the dissipative quartz crystal microbalance(QCM-D)was used to monitor the mass growth and viscoelastic changes of(Ti O₂-PSS)_n and(PDAC-PMMA)_n.In the thesis,a facile aqueous-based Lb L dip-coating method was successfully utilized to fabricate[(Ti O₂-PSS)_n/(PDAC-PMMA)_n]_m 1D PCs with brilliant structural colors on the flat glass substrates,and investigated the effect of assembly temperature on uniformity of the structural color.By changing the thickness of the film,the incident angle and the number of stacks,the position of the photonic band gap is adjusted to realize the PC with multi-color output,such as purple,blue,green,yellow-green,and red.And colored 1D PCs also were prepared on the surface of curved glasses.Based on the pores structure of the photonic crystal and the swelling properties of PMMA,the photonic band gap is red-shifted to expose the film of 1D PCs to organic solvent vapor with good reproducibility.At the same time,1D PCs with different patterns can be obtain by using a mask.The structure of 1D PCs has application prospects in gas sensing and decoration in this work.Sodium alginate further was chosen to prepare 1D PCs with the same progress on the glass substrate in order to broaden the applicability of material selection.