| Colloidal photonic crystals(CPS),inspired by the natural photonic crystal structure,are prepared by the self-assembly of monodispersed latex particles.Due to the appearance of bright color and high color saturation,CPS can be used as of chemical and biological sensors to detect specific analytes.However,there are lots of disadvantages for traditional photonic crystal membranes based on styrene(St)as matrix material,such as single functionality,high brittleness,hard to peel off the membrane from mould,slow response rate,etc..Two types of mono-dispersed functional microspheres of Poly(Styrene-co-Allylamine)(Poly(St-co-AA))and Poly(Styrene-co-N-Hydroxymethyl acrylamide)(Poly(St-co-NMA))have been successfully fabricated by soap-free emulsion polymerization(SFEP)in this article.Then,the 2D photonic crystal nanocomposite hydrogel sensor and crack-free self-crosslinked 3D photonic crystals were built with the adoption of needle tip flow technique and the vertical deposition self-assembly method respectively.Moreover,their chemical composition,particle size and distribution,the response properties and optical properties are studied.The main work was carried out by the following two parts:(1)Learning from the idea of nanocomposite,with inorganic nano-clay hectorite(LMSH)as physical crosslinking agent,the 2D photonic crystal nanocomposite hydrogel membrane with thermo-sensitivity and quick swelling rate was fabricated by the combination of Poly(N-isopropyl acrylamide)(Poly(NIPAm/LMSH))nanocomposite hydrogel and 2D Poly(St-co-AA)photonic crystal.The chemical composition of the product was confirmed,the effect of initiator's concentration and AA/St volume ratio on the hydrodynamic diameter(DH),polydispersity index(PDI)of Poly(St-co-AA)microspheres was systematical studied.Also,the morphology and particle spacing of photonic crystal in the nanocomposite hydrogel membrane under different temperature and swelling time were explored.Results show that with increasing the AA/St volume percentage from 4%to 8%,the DH of Poly(St-co-AA)microspheres decreased to 471.8 nm from 655.7 nm,the PDI value ranged from 0.034 to 0.134.When the temperature was adjusted to 37?,the photonic crystal nanocomposite hydrogel membrane can peel off automatically from the glass slide.When the swelling time increased from 0 to 8 min,the particle spacing of microspheres in hydrogel membrane increased from 654 nm to 1128 nm,showing potential application value in the fileds of temperature/humidity detection.The Poly(St-co-NMA)microspheres which possess core-shell structure and the surface containing active-OH groups have been prepared by soap-free emulsion polymerization.the successfully copolymerization of was confirmed by FTIR,XPS,and EA confirmed that St and NMA have been successfully copolymerized.The effect of different NMA/St mass percentages on the particle size and monodispersity of microspheres was explored.It was found that with increasing NMA/St mass percentage from 5.5%to 28%,the DH of microspheres decreased from 347.6 nm to 192.8 nm,and the PDI value of the microspheres were all below 0.05.Then taking advantage of the condensation of hydroxyl,the crack-free self-crosslinked 3D photonic crystals membrane was fabricated by vertical deposition method.The 3D photonic crystals membrane shows high transparency,strong resistance to water,characteristics of structural color in the water,and a single and sharp diffraction peak at 432 nm was found.In addition,the 3D photonic crystals membrane have been produced both by the horizontal deposition and freeze-drying method,the difference of arrangement of the microspheres and optical performance have been contrastively researched.It's confirmed that it is a practical way to prepare 3D photonic crystals by the freeze-drying method,and it provides a new choice for the preparation of 3D photonic crystals. |
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