Preparation And Properties Of Photonic Crystal Paper Based On Phase Change Matrix

Among various types of responsive photonic crystals,magnetic response photonic crystals have broader application prospects due to their fast magnetic responsiveness and color resolution.Compared with other nano-Fe3O4 preparation methods,solvothermal method has unique advantages,however,the research work on the nucleation mechanism of nano-Fe3O4 crystal in solvothermal method is rare.Photonic crystal paper,especially multi-responsive photonic crystal paper,as an important research field of photonic crystal,has been a hot issue in current research.In this paper,a modified solvothermal method is used to prepare a high crystallinity magnetic response photonic crystal by adjusting the ratio of ferrous iron to ferric ion.The nucleation mechanism of Fe3O4 nanocrystals is explored,and then the temperature sensitivity of high critical solution temperature is used.The phase change material is a matrix to prepare a temperature sensitive photonic crystal paper which have a temperature window.It's found that when the current precursor does not contain Fe²⁺,the product has a large amount of nano-?-Fe₂O₃ impurities,which is poor in monodispersity and superparamagnetism.In this paper,the nucleation mechanism of nano-Fe3O4 was explored from the perspective of coordination chemistry.The concept of Fe²⁺-Fe³⁺dinuclear mixed-valence bridge-bond complex seed crystal was proposed.The results show that nano-Fe3O4 with uniform particle size,good monodispersity and superparamagnetism was prepared by adding Fe²⁺to the precursor.It is found that the increase of Fe²⁺content will reduce the size of primary and secondary particles and increase the crystallinity.The Fe²⁺content has a close correlation with the size of primary and secondary Fe₃O₄,indicating that Fe²⁺-Fe³⁺dinuclear mixed-valence bridge-bond complex has the function of nucleating seeds.Based on the above research work,an improved method for reductant to control nano-Fe3O4 was proposed,where it was studied that relationship between the amount of ascorbic acid and oxalic acid added and the primary crystal grains and secondary particles of the synthesized product.The results showed that the particle size and the size of the primary crystal grains decrease as the amount of the reducing agent added increases,and the crystallinity increases as the amount of the reducing agent increases.The photonic crystal paper based on PEG/PMMA/IPA three-phase composite phase change matrix was prepared by using modified St?ber to prepare Fe₃O₄@SiO₂colloidal particles and combining magnetic induction with self-assembly and MMA radical polymerization.The microstructure,composition,phase transition temperature and optical properties of photonic crystal paper were studyed.Optical performances of the typical photonic crystal paper suggest that photonic crystal paper has unique temperature window property.The paper has a special temperature discoloration characteristic in 29³8°C.The influencing factors,including the content of IPA,the mass ratio of PEG and PMMA,and the molecular weight of PEG on its optical properties were discussed.With the increase of IPA,the temperature window of photonic crystal paper becomes wider,the upper critical temperature value increases gradually,the lower critical window value does not change significantly,and the red shift range gradually increases.When the molecular weight of PEG is 1000 and the mass ratio of PEG to PMMA is 4:1 or 1:4,the photonic crystal paper does not have a temperature window,but the former has thermochromic properties.When the molecular weight of PEG is 2000,except for the the mass ratio of PMMA to PEG-2000 is 2:1,photonic crystal papers whose the mass ratio is 6:2,4:1,5:1 all have temperature range.When the molecular weight of PEG is large,the degree of expansion and contraction and the rate of expansion and contraction of the photonic crystal paper can be increased.