【作者】 王琛；

【导师】 胡春艳；

【作者基本信息】 东华大学 ， 纺织科学与工程， 2025， 硕士

【摘要】 传统的多孔电磁屏蔽材料（如气凝胶）普遍存在力学性能差、填料浓度高等问题,而单一组分水凝胶材料在结构设计方面也存在不足,难以同时满足优异的力学性能和电磁屏蔽性能（EMI SE）需求。为解决上述问题,本研究结合多孔材料和水凝胶的优势,设计了一种基于MXene（Ti₃C₂T_x）增强的复合水凝胶屏蔽材料。通过单向冷冻技术构建了单向多孔壁结构,并结合复杂的多网络结构设计,显著提升了材料的机械性能。同时利用水分子的高介电和极化特性,实现在较低填料浓度下的优异电磁屏蔽性能。该材料封装为传感器后,表现出高灵敏度、快速响应及优异的稳定性,展现其在智能可穿戴设备及信息加密领域的广阔应用潜力。具体内容如下:（1）MXene/PVA/CS/Fe₃O₄复合水凝胶的制备:通过单向冷冻技术,构建仿生单向多孔壁结构的MXene/PVA/CS/Fe₃O₄复合水凝胶。其中,壳聚糖（CS）作为刚性网络,聚乙烯醇（PVA）作为柔性网络,协同单层MXene和Fe₃O₄纳米颗粒,形成丰富的界面和交联网络,显著提升水凝胶的拉伸强度（320 k Pa）和模量（650 k Pa）。（2）MXene/PVA/CS/Fe₃O₄复合水凝胶的电磁屏蔽性能:探究复合水凝胶在X波段（8.2-12.4 GHz）的电磁屏蔽性能及损耗机制。分析导电填料浓度、材料厚度及含水量等因素对于屏蔽性能的影响规律:当厚度从0.81 mm增加到5.04 mm时,EMI SE从20.6d B显著提升至63 d B;随着MXene浓度从0.4 wt%增加到1.5wt%,EMI SE由18.6 d B增加到49.3 d B;当水凝胶的含水量达到76 wt%,最佳EMI SE达到66.7d B。通过调节含水量,实现对屏蔽性能的可逆调控,并显著增强储存稳定性。（3）ANFs/MXene/PVA复合水凝胶的制备:为进一步优化水凝胶力学性能及稳定性等,引入芳纶纳米纤维（ANFs）作为刚性增强相,与MXene协同增强PVA水凝胶。通过冰模板法、溶液交换及盐析等策略,构建单向多孔细胞壁结构,并实现了ANFs的再质子化。通过调控ANFs与PVA的比例的方法优化孔隙结构,使水凝胶的压缩强度提升至6 MPa,可承受自身重量250倍的载荷。（4）ANFs/MXene/PVA复合水凝胶的电磁屏蔽及压力传感性能:探究该多孔材料在X波段的电磁屏蔽性能及压力传感特性。水凝胶表现出优异的EMI SE:随着厚度由0.78 mm增加到4.70 mm,EMI SE由16.4 d B增加到60.2 d B;当MXene含量由0.4 wt%增加到1.5 wt%,EMI SE由24.5 d B增加到52.0 d B;含水量由0wt%增加到95 wt%,EMI SE由7.9 d B增加到51.5 d B。此外,该材料表现出优于上述工作的储存稳定性及热稳定性等,同时具备优异的传感性能(灵敏度0.31k Pa^-1,响应时间210 ms)。其良好的生物相容性、可重复性及环境稳定性,使其成为智能可穿戴设备和信息加密材料的理想候选者,为多功能电磁屏蔽材料的开发提供了新思路。更多还原

【Abstract】 Traditional porous electromagnetic shielding materials（such as aerogels）generally suffer from poor mechanical properties and high filler concentrations,while single-component hydrogel materials also face limitations in structural design,making it difficult to simultaneously achieve excellent mechanical properties and electromagnetic interference shielding performance（EMI SE）.To address these issues,this study combines the advantages of porous materials and hydrogels to design a composite hydrogel shielding material enhanced with MXene（Ti₃C₂T_x）.By employing unidirectional freezing technology,a unidirectional porous wall structure was constructed,and a complex multi-network design was incorporated to significantly enhance the mechanical properties of the material.Additionally,leveraging the high dielectric and polarization properties of water molecules,excellent EMI shielding performance was achieved at low filler concentrations.When encapsulated as a sensor,the material demonstrated high sensitivity,fast response,and excellent stability,showcasing its broad application potential in smart wearable devices and information encryption.The specific details are as follows:（1）Preparation of MXene/PVA/CS/Fe₃O₄ composite hydrogels:The composite hydrogels with bionic unidirectional porous wall structure are constructed by unidirectional freezing technique.Among them,chitosan（CS）as a rigid network and polyvinyl alcohol（PVA）as a flexible network synergized with monolayers of MXene and Fe₃O₄ nanoparticles to form a rich interfacial and cross-linking network,which significantly enhances the tensile strength（320k Pa）and modulus（650 k Pa）of the hydrogel.（2）Electromagnetic Shielding Properties of MXene/PVA/CS/Fe₃O₄ Composite Hydrogels:This study investigates the electromagnetic interference（EMI）shielding performance and loss mechanisms of the composite hydrogels in the X-band（8.2–12.4 GHz）.The effects of conductive filler concentration,material thickness,and water content on shielding efficiency are systematically analyzed:when the thickness is increased from 0.81 mm to 5.04 mm,the EMI SE is significantly increased from 20.6 d B to 63 d B;with the increase of the MXene concentration from 0.4 wt%to 1.5 wt%,the EMI SE is increased from 18.6 d B to 49.3 d B;when the hydrogel’s water content reaches 76 wt%,the optimal EMI SE reaches 66.7 d B.By adjusting the water content,the reversible tuning of the shielding performance is realized and its storage stability is significantly enhanced.（3）Preparation of ANFs/MXene/PVA composite hydrogels:In order to further optimize the hydrogel mechanical properties and stability,etc,aramid nanofibers（ANFs）are introduced as a rigid reinforcing phase to synergistically enhance the PVA hydrogel with MXene.The unidirectional porous cell wall structure is constructed and the re-protonation of ANFs is achieved by strategies such as ice template method,solution exchange and salt precipitation.The pore structure is optimized by modulating the ratio of ANFs to PVA,which enhances the compressive strength of the hydrogel to 6 MPa and can withstand a load of 250 times its own weight.（4）Electromagnetic Shielding and Pressure-Sensing Properties of ANFs/MXene/PVA composite hydrogels:The study reveals the electromagnetic shielding performance in the X-band（8.2-12.4 GHz）and excellent pressure-sensing properties of ANFs/MXene/PVA composite hydrogels.The hydrogel exhibits remarkable electromagnetic interference shielding effectiveness（EMI SE）:with the increase of thickness from 0.78 mm to 4.70 mm,the EMI SE increases from 16.4 d B to 60.2 d B;with the increase of MXene content from 0.4 wt%to 1.5wt%,the EMI SE increases from 24.5 d B to 52.0 d B;with the increase of water content from0 wt%to 95 wt%,the EMI SE increases from 7.9 d B to 52.0 d B.In addition,the material exhibits storage stability and thermal stability superior to the above work,as well as excellent sensing performance(sensitivity 0.31 k Pa^-1,response time 210 ms).Its good biocompatibility,reproducibility and environmental stability make it an ideal candidate for smart wearable devices and information encryption materials,providing new ideas for the development of multifunctional electromagnetic shielding materials.更多还原