Development And Properties Of Hierarchically Porous Ti₃C₂T_X/Polymer Composite Foam For Wave-Absorption

As a new type of highly conductive two-dimensional material,Ti₃C₂T_x,one of the transition metal carbides has attracted much attention in the field of electromagnetic absorption materials because of its abundant surface functional groups,special structural characteristics,and mature preparation technology.However,there are some issues for Ti₃C₂T_x nanomaterials such as a dense stacking phenomenon,and the excellent electrical conductivity can cause impedance mismatch problems,which restricts its microwave absorption performance in practical applications.In order to solve the above problems,this paper used the chemical exfoliation method to obtain few-layered two-dimensional Ti₃C₂T_x nanosheets with a large aspect ratio.Based on the few-layered Ti₃C₂T_xnanosheets,a three-dimensional hierarchically porous polyaniline(PANI)/Ti₃C₂T_x composite is successfully constructed via in-situ polymerization coupling with self-assembly method to solve the existing stacking phenomenon and impedance mismatch problems.And on this basis,different polymer-based composite foam for wave-absorption were prepared by different methods such as immersion method and thermally induced phase separation method.The morphology and structural characteristics of the materials were analyzed by multi-scale characterization methods.Herein,the microwave absorption properties and its regulation were emphatically discussed,and the multi-functional application potential of the foams was explored.The specific research content is as follows:First,the PANI/Ti₃C₂T_x composites with three-dimensional hierarchically porous structure were prepared by the in-situ polymerization coupling with self-assembly methods,which using the aniline as the monomer,dodecylbenzene sulfonic acid(DBSA)as the doping acid and the few-layer two-dimensional Ti₃C₂T_x nanosheets as the carrier.The microscopic morphology and structure of the composites were characterized,and the formation mechanism of three-dimensional hierarchically porous structure was discussed and analyzed further.The results showed that DBSA is an important driving force for the three-dimensional hierarchically porous structure of PANI/Ti₃C₂T_x composites.The electromagnetic parameters of the PANI/Ti₃C₂T_x composites are investigated by the vector network analyzer,and the absorbing performance is calculated according to the electromagnetic transmission line theory.The results show that when the mass ratio of the Ti₃C₂T_x nanosheets to the aniline monomer is 1:1,the lowest reflection loss can reach to-53.79 d B at 12.67 GHz with 10 wt%loading,and the thickness is only 1.33 mm.The excellent absorbing performance of PANI/Ti₃C₂T_x composite absorber is mainly due to the PANI modified Ti₃C₂T_x nanosheets that optimize the impedance matching characteristics,synergistically enhance the dielectric loss performance of the material,and its special three-dimensional hierarchically porous structure expand the multiple reflection loss capability of the PANI/Ti₃C₂T_x composites.On the basis of the above research,the PANI/Ti₃C₂T_x-PVDF composite foam is prepared by a simple immersion adsorption method that the PANI/Ti₃C₂T_x composite is used as the functional wave absorption agent,and the high dielectric properties polyvinylidene fluoride(PVDF)foam prepared by the sodium chloride template method is used as the matrix.The morphology and structure of the composite foam were analyzed by multi-dimensional characterization and analysis methods.The vector network analyzer was used to test the electromagnetic parameters of the composite foam.The focus is the effects of a series of PANI/Ti₃C₂T_x composite microwave absorption agents(with different mass ratios of PANI and Ti₃C₂T_x)on the electromagnetic parameters and performance for the different foam systems.The results show that the loading of the microwave absorption agent with fixed component ratio in the PANI/Ti₃C₂T_x-PVDF composite foam increases,the permittivity of the composite foam increases accordingly.When the Ti₃C₂T_xcomponent in the PANI/Ti₃C₂T_x composite increases,the amount of wave-absorption agents required for the corresponding PANI/Ti₃C₂T_x-PVDF foam to achieve the optimal microwave absorption performance shows a downward trend.A number of PANI/Ti₃C₂T_x-PVDF composite foam samples showed excellent microwave absorption properties in the X band.At the same time,the research also conducted organic solvent adsorption performance and thermal insulation performance tests on PANI/Ti₃C₂T_x-PVDF composite foam,and both showed good functional properties.Preliminary exploration confirmed the application potential of the material with multi-functional characteristics.Finally,in order to expand the application of microwave absorption materials in complex electromagnetic environments,we will further explore the preparation of novel compressible composite microwave absorption foams with adjustable electromagnetic parameters(microwave absorption properties).The research prepared the compressible PANI/Ti₃C₂T_x/EVA composite through the thermally induced phase separation method that using PANI/Ti₃C₂T_x composite as the functional wave absorber and selecting the highly elastic ethylene-vinyl acetate(EVA)resin as the foam matrix.The morphology and structure of the composite foam were characterized and analyzed by multiple characterization methods.The electromagnetic parameters and microwave absorption properties of the composite foam under different compression ratios were tested and analyzed by the vector network analyzer.The results show that as the compression rate of the PANI/Ti₃C₂T_x/EVA composite foam increases,the real part of dielectric constant increases.The samples with different compression rates can achieve the best electromagnetic absorption performance in different frequency bands.The electromagnetic parameters of the PANI/Ti₃C₂T_x/EVA can be dynamically adjusted by controlling the compressibility and its microwave absorption property can achieve full-frequency absorption in the X-band.It provides a new idea for exploring and developing novel microwave absorption materials for complex electromagnetic environments.