Preparation And Application Of Photopolymerizable Magnetic Cationic Monomers-based Multifunctional Organic Absorbing Gel

The severity of electromagnetic radiation pollution and the complexity of the application environment make the integration of multiple functions into a single material a very urgent goal.Multifunctional absorbing materials are extremely attractive for new generations of radio technology as well as for small electronic devices.Traditional wave-absorbing materials are limited in their application due to complex preparation processes and poor transparency caused by fillers.In this study,in order to realize a highly transparent multifunctional and efficient microwave absorbing material,from the electromagnetic wave loss mechanism and absorption theory,we consider:1)the flexible gel has a good performance in optical transparency,tensile performance and electrical conductivity（good conduction loss）;2)the simplicity and efficiency of the photopolymerization;3)The addition of rare earth elements introduces a moderate amount of magnetic loss to the gel without affecting the overall optical properties of the gel;4)The introduction of strong polar organic solvents can provide the gel with good resistance to freezing and to microwave dielectric loss.A photopolymerizable magnetic cationic monomer was first synthesized by using photopolymerizable cationic monomers as precursors and ion exchange and coordination reactions to introduce rare earth elements.The monomer was then dissolved in organic solvents and the appropriate amount of cross-linker and photoinitiator was added to produce a highly transparent organogel with good microwave absorption in a rapid and convenient manner by light curing.By characterizing the electromagnetic parameters of the gels and applying the theoretical knowledge of electromagnetic wave loss and absorption,we have mainly investigated the effect of the ratio of photopolymerizable magnetic cationic monomer to solvent and the content of the crosslinker on the electromagnetic parameters and ultimately on the microwave absorption of the organogels.In addition,we have also investigated the multifunctional properties of the gels,such as anti-freezing properties,transparency,electrical conductivity and mechanical properties.In this study,the photopolymerizable magnetic cationic monomer[DAC]₅[Dy（NCS）₈]was dissolved in dimethyl sulfoxide（DMSO）to form a solution and highly transparent ionic organogels were prepared by light curing.Both components of organogel,which are the photopolymerizable magnetic cationic monomer and polar solvent DMSO,have an important effect on the magnetic losses and dielectric losses properties of the organogel respectively.By tuning the mass ratio of DMSO to[DAC]₅[Dy（NCS）₈]and the content of the cross-linker,the complex permittivity of the gel could be effectively adjusted to improve the impedance matching,and finally a gel with excellent wave absorption properties and good tensile properties was obtained.The optimum organogel was fabricated with a minimum reflection loss of-45.9d B and a broadest effective absorption bandwidth（EAB）of up to 5.2 GHz,and effective absorption in the millimeter band（26.5-40GHz）which is within the fifth generation（5G）mobile networks.The multifunctional organogel has the advantages of simple preparation,arbitrary shape,good frost resistance,good adhesion to a wide range of substrates and complex surfaces,which allows it to be used in complex scenarios where both optical transparency and electromagnetic wave absorption are required,and also shows potential for wider applications in the booming 5G era.Its good electrical conductivity and the special wavelengths of light（near infrared）absorption conferred by its internal rare earth ions,make it a flexible sensor with a multi-dimensional stimulus-electric response.