纤维素气凝胶的制备及应用

纤维素气凝胶被称为"第三代气凝胶材料",具有可再生性、生物降解性、高孔隙率、高比表面积、低密度以及3D互连的多孔网络结构的特点,可应用于吸附与分离材料、隔热材料、生物医学材料以及许多其他领域。基于纤维素气凝胶优异的性能,可进一步拓宽其应用,将纤维素气凝胶作为改性剂或功能添加剂应用于塑料改性,使塑料制品具有弹性、低膨胀性和更好的力学性能。对纤维素气凝胶的分类进行介绍,论述了相关的制备方案,对比了超临界干燥、冷冻干燥和常压干燥等干燥特点,探究了纤维素气凝胶在吸附与分离、生物医学、保温隔热和塑性材料改性等方面的应用,并提出了未来可尝试的研究方向。     

生物质基碳气凝胶的研究进展

碳气凝胶是一种新型的纳米多孔碳材料,具有孔隙率高、比表面积大、导电性能优良、耐高温等优点,在催化剂载体、电容器及吸附材料等领域具有广阔的应用前景。与传统的碳气凝胶相比,生物质基碳气凝胶具有前驱体环保可再生的优势,可为生物质高值化、功能化利用提供新思路。本文在简单介绍生物质基碳气凝胶制备过程（包括溶胶-凝胶化、干燥、炭化）的基础上,重点介绍了3类来自不同生物质前驱体（植物纤维素、细菌纤维素和具有三维多孔结构的植物本身）碳气凝胶的制备方法,并对碳气凝胶及其复合材料在催化剂载体、吸附材料、超级电容器、锂离子电池方面的应用进行了综述,最后对生物质基碳气凝胶的研究方向和发展前景进行总结和展望。     

气凝胶的阻燃性能研究进展

气凝胶是一种纳米多孔材料,具有超轻、绝热和隔音等特性,在建筑节能保温领域具有广阔的应用前景,但气凝胶的阻燃性能是限制其应用的瓶颈之一.本文在探讨气凝胶燃烧机理的基础上,综述了无机气凝胶和有机气凝胶的阻燃性能研究进展,对几种常见的阻燃气凝胶进行了分析和对比,展望了气凝胶的未来产业应用前景.     

木质纤维素气凝胶的制备及性能表征的研究

纤维素是自然界中储量最为丰富的一种天然高分子,纤维素气凝胶作为无机气凝胶和合成聚合物气凝胶之后的第三代气凝胶,兼具绿色可再生的纤维素材料和多孔气凝胶材料的优点,成为纤维素材料研究与应用的一个热点。本文内容包括木质纤维素的提取、碱性溶剂(尿素/NaOH)的溶解、纤维素气凝胶的制备与表征,包括sol-gel的形成、冷冻干燥工艺的制定、SEM、FTIR、BET等性能的测试表征,对木质纤维素气凝胶用MTMS硅烷进行疏水改性,对纤维素气凝胶在物流、港口行业应用的展望。     

产品开发

正二氧化硅气凝胶隔热材料发展前途光明二氧化硅气凝胶是一种新型多孔功能材料,因其具有高孔隙率、低热导率、低介电常数、高比表面积、材质半透明等优良特性,从而成为新型超级隔热材料,在超级隔热材料、吸附材料、催化剂和载体等许多领域具有广阔的应用前景。但其缺点是柔韧性、整体性较差,常温干燥制备的产品开裂较严重,限制了其应用。近年来,通过原位溶胶-凝胶法和模压成型法制得的二氧化硅气凝胶复合材料,提高了其     

咪唑盐型离子液体[Cnmim][x]在SiO2气凝胶制备过程中的应用进展

SiO2气凝胶是一种低密度、高孔隙率、高热阻和低声阻的固体多孔材料,具有广泛的应用前景.文章从气凝胶制备方法,离子液体结构以及离子液体在气凝胶制备过程中对气凝胶性能和结构影响方面进行了综述,并对离子液体在气凝胶制备过程中的发展前景进行了展望.     

石墨烯气凝胶复合材料制备及吸附性能的研究进展

石墨烯气凝胶(GA)拥有以石墨烯为主体的多孔互联三维海绵状网络结构。作为一种新兴的纳米多孔材料,因其具有高疏水性、高比表面积、高孔隙率以及良好的化学稳定性,在吸附领域具有巨大的应用前景。结合相关研究,重点介绍了石墨烯、纤维素/石墨烯、碳纳米管/石墨烯、氮掺杂/石墨烯、金属氧化物/石墨烯等几种体系的气凝胶材料的制备方法,并对其吸附性能的研究进展进行了阐述。     

纤维素气凝胶及其疏水改性研究进展

纤维素气凝胶具有的低密度(≥8 kg/m~3)、低热导率(0.0201~0.0295 W/m·K)、高孔隙率(≤99.5%)、高比表面积(100~605 m~2/g)等使其在隔热、吸附、催化、储能等领域应用广泛,是多功能、轻质、纳米多孔材料。纤维素表面存在大量的羟基,氢键和亲水性使纤维素气凝胶在吸附油污等应用受限。利用三甲基氯硅烷(TMCS)、十八烷基三氯硅烷(OTS)等进行纤维素气凝胶的疏水改性,拓展其应用范围。     

纤维素复合气凝胶制备技术及其在生物医药领域的研究进展

新生代的纤维素气凝胶材料兼具传统气凝胶的优良特性及自身优良生物相容性和可降解性,在生物医药等领域应用前景广阔。本研究简述了纤维素气凝胶的制备过程,综述了直接添加/生成法、构建客体法和直接包覆法三种常见的纤维素复合气凝胶制备技术,列举了纤维素气凝胶在药物运载系统、组织工程等生物医药领域的应用,最后对纤维素气凝胶材料的发展前景和研究方向进行了展望。     

生物基阻燃剂在纤维素基材料中的应用研究进展

纤维素基高分子材料应用广泛,但其具有易燃的特性,提升其阻燃性能非常重要。介绍了生物基高分子作为炭源应用于膨胀型阻燃剂体系中,综述了生物基高分子在棉织物、纸张、纤维素气凝胶等纤维素基高分子材料中的应用和研究现状,展望了生物基阻燃剂在纤维素基材料中的应用前景。     

气凝胶复合材料的研究进展

气凝胶材料是一种质轻、低密的多孔材料,对其研究较多。它具有良好的发展前景和巨大的科研价值。通过介绍高分子气凝胶、碳气凝胶等复合材料的制备方法,阐述了结构与性能的关系,并对气凝胶材料未来的发展作了展望。     

碳气凝胶电极用于NaCl溶液电容性除盐的研究

碳气凝胶是一种新型多孔碳材料,具有比表面积大、电导率高的特点。本文通过常压干燥制备了碳气凝胶,研究测试了其结构特性,用N aCl溶液模拟海水,利用CD I原理,以碳气凝胶作电极进行了N aC l溶液的除盐实验。实验表明,决定碳气凝胶的除盐效果的主要因素为比表面积和电导率。在不同配比结构中,以R/C为1500、M值为30%的碳气凝胶电极的除盐效果最佳。利用双电层电容模型解释探讨了碳气凝胶电极的除盐机理。     

酚醛基炭气凝胶的研究进展

炭气凝胶是一种多孔纳米炭材料,具有低密度、高孔隙率、高比表面积、优异的导电性和良好的成型性能等优点,是炭材料研究的热点和重要方向。本文旨在通过阐明酚醛基炭气凝胶的制备原料和制备工艺的发展过程,从而突出未来酚醛基炭气凝胶的发展方向。基于此,本文首先重点介绍了酚醛基炭气凝胶的制备方法,主要包括溶胶-凝胶化、干燥以及炭化过程三个最主要的步骤;进而详述了以三种不同的前体,即间苯二酚、苯酚、生物质单宁/木质素分别制备酚醛基炭气凝胶的方法及其优缺点;接下来对酚醛基炭气凝胶作为吸附材料（气体吸附/液体吸附）的吸附量以及在电化学储能以及其他领域的应用进行了综述;最后对酚醛基炭气凝胶未来的研究方向和发展前景进行了总结和展望。文章指出,传统的以间苯二酚为原料辅以超临界干燥的方法制备的酚醛基炭气凝胶,原料成本较高,反应条件苛刻,实际生产应用受限;以苯酚取代间苯二酚,亦或是采用冷冻干燥等方法改进其制备工艺,可以大幅度降低原料和生产成本;但未来的发展方向和重点将是绿色、可再生的生物质原料（单宁、木质素、腰果酚等）及复合气凝胶材料的研发。因此,酚醛基炭气凝胶在未来的发展还需要进一步改进其制备工艺和方法,拓宽其原料来源,从而提高性能,扩大应用领域。     

Fabrication and application of porous materials made from coal gangue: A review

Coal gangue (CG), which is mainly generated during coal excavation, mining, and coal washing, is an industrial solid waste that is recognized as an environmental pollutant. The ever-increasing amount of CG produced is a serious threat to the ecological environment and property safety, especially in China, which is the largest coal producer and consumer in the world. Considerable studies have investigated means for utilizing CG worldwide. This review summarizes and discusses various porous inorganic materials made from CG, including cement-based porous materials, porous bricks, porous ceramics (cordierite and mullite) and glasses, porous geopolymers, zeolites, aerogels, and porous carbon materials. Different preparation processes and performances of each type of porous inorganic materials were reviewed. Porous CG-based materials can be used as promising adsorbents for the removal of various pollutants and have good potential for use in construction industry as well as catalyst material applications. Besides, porous materials obtained from CG have also been tested as slow-release fertilizers after the absorption of phosphate, as electrode materials, and as oil-in-water separation agents. The systematic summary of porous materials based on CG aims at promoting high-value-added applications for this waste. Future research directions for the use of CG as a raw material are also presented.     

Hydrophobic,Pore‐Tunable Polyimide/Polyvinylidene Fluoride Composite Aerogels for Effective Airborne Particle Filtration

Polyimide (PI) aerogels have great potential as filter materials, owing to their unique porous structure and excellent thermodynamic properties. In this work, polyvinylidene fluoride (PVDF) is introduced into the 3D network structure of crosslinked PI by phase separation to prepare PI/PVDF hybrid aerogels. By adding different amounts of PVDF, effective control of the aerogel porous structure is achieved, as a result, the air permeability of the hybrid aerogel is significantly improved while still achieving a filtration efficiency of airborne particulates of more than 99.8%. PVDF is aggregated and dispersed on the surface or inside of the aerogel in the form of nanoparticles, which effectively increases the hydrophobicity of the material. The contact angle of the prepared PI hybrid aerogel is ≈150°, and the water absorption is as low as 2.2%, which enables the aerogel to maintain structural stability in humid environments. In addition, the aerogel exhibits good adsorption effects on organic solvents.     

Load Transfer Behavior of 3D Aerogels Fabricated with Halloysite Nanotubes

Nanofibrous network aerogels as an important class of porous material have received enormous attention in materials research. However, the fabrication of nanofibrous network aerogels with short fiber as building blocks is extremely challenging, since it is difficult for them to build 3D network structures spontaneously from the topological point of view. Here the synthesis and load transfer behavior of 3D aerogels composed of halloysite nanotube (HNT) short fibers are described. The resulting aerogels take inorganic materials as the skeleton, elastic organic materials as the connection point, and exhibit inorganic/organic phase interfaces. Confocal Raman microscopy system is utilized to investigate the structural‐dynamic profile of halloysite clay aerogels (HCAs) under applied load. The results indicate that the deformation mainly occurs in the polysiloxane (PSO) molecular chain connected with the HNT skeleton. HCAs have a certain load transfer capability, and the PSO chains between tubes are strong enough to support the HCA skeleton.     

Organic and carbon aerogels derived from poly(vinyl chloride)

Organic aerogels were derived from dimethylformamide solution of poly(vinyl chloride) (PVC) via dehydrochlorination using a strong base, 1,8-diazabicyclo[5,4,0]undec-7-ene, and supercritical drying using carbon dioxide. From these organic aerogels, carbon aerogels were yielded via stabilization and carbonization. Changes in the porous structure of the aerogels during the preparation process and influences of the preparation conditions on the porous structure were investigated. The framework of the aerogels composed the walls of the meso- and macropores. The volume and the size of these pores were reduced during stabilization and carbonization due to the shrinkage of the framework caused by the release of decomposition gases and densification of the material. Simultaneously, the release of decomposition gases produced additional micropores. The extent of dehydrochlorination, the concentration of PVC in the starting solution and the molecular weight of PVC were the factors with which the porous structure of the aerogels could be controlled over a wide range. In addition, the stabilization conditions notably influenced the carbonization behavior of the organic aerogels and the porous structure of the carbon aerogels. The optimum stabilization conditions that minimized the loss of mass and maximized the pore volume of the carbon aerogels were determined.     

炭气凝胶的制备、性能及应用

炭气凝胶是一种新型、轻质、纳米、多孔、非晶态炭材料,具有可在纳米尺度控制和剪裁的连续的三维网络结构,具有许多优异的性能和广阔的应用前景。通过结合所从事研究工作,综述了气凝胶的制备、性能及应用,分析了目前存在的问题和发展前景。     

Enhancing the thermal insulation properties of polymer-derived SiCN(O) ceramic aerogels with a polysilazane-precursor design

In this study, we investigated the tunable porous structure of SiCN(O)-derived ceramic aerogels by changing the molecular structure of the polysilazanes from linear to branched. We also studied the effect of molecular structure on the thermal insulation properties of ceramic aerogels. As the percentage of branched molecular structure in the polysilazane precursor increased, the internal microscopic pore structure of the aerogels changed from macroporous to mesoporous. The specific surface areas and pore volumes of the ceramic aerogels prepared with different precursors increased after pyrolysis at 1000 °C, ranging from 3.7 to 255.9 m²/g and 0.01–0.36 cm³/g, respectively. The corresponding thermal conductivities increased slightly as the aerogels contracted after pyrolysis. The low thermal conductivity (0.046 W/(m·K) at minimum) can be attributed to the decrease in pore size caused by adjusting the precursor structure, which limits the thermal conduction of gas in the porous aerogel materials.