石墨烯基气凝胶的制备及油吸附性能研究进展

海上漏油的频繁发生以及采油废水、工业含油污水的大量排放造成水资源大片污染和生态系统平衡的严重破坏。目前，从水体中分离油品和有机污染物已受到越来越多的商业和学术的关注。石墨烯基气凝胶是由二维石墨烯片层组装成的三维宏观材料，因其孔隙率高、比表面积大、密度低、机械性能强等特点在油水分离领域具有广阔的应用前景，已成为当今的研究热点之一。本文结合最新研究进展系统地总结了石墨烯基气凝胶的结构设计、组装及干燥方法，归纳了近年来其在油水分离中的应用进展，并对石墨烯基气凝胶在油水分离领域的研究现状和未来研究方向做了简要评述，以期为该领域的深入探索提供新的视角。     

还原氧化石墨烯水溶胶与气溶胶的制备及其应用

以氧化石墨(GO)为原料、铜纳米粒子为还原剂,制备得到三维还原氧化石墨烯水溶胶H;通过冷冻干燥,得到相应的还原氧化石墨烯气溶胶A。以得到的H催化还原对硝基苯酚(4-NP),结果表明,H对4-NP还原有良好的催化性能。     

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。     

Fast Chemo‐Responsive Shape Memory of Stretchable Polymer Nanocomposite Aerogels Fabricated by One‐Step Method

A new type of stretchable poly(caprolactone)/graphene oxide (PCL/GO) aerogel with fast chemo‐responsive shape memory effect is fabricated by one‐step method of a sol‐gel procedure. The PCL/GO aerogels show uniformly circular and interconnected pores formed by twisted PCL nanolayers. GO platelets improve the crystallinity of PCL and increase the fracture stress and strain by 150% and 300% respectively, although the GO loading is only 0.5%. The dramatic increment of break strain is attributed to the uniform and circular pores that can afford large deformation and the interaction of GO and PCL. The aerogels can be programmed by external stress at ambient temperature without heating and recover upon ethyl acetate (EA) in 1 s. The fast chemo‐responsive shape recovery is ascribed to the fast wrinkle of the PCL nanolayers that decrease the diffusion time greatly and the interconnected micrometer pores that are in favor of penetrating for EA molecules.     

Double Dianhydride Backbone Polyimide Aerogels with Enhanced Thermal Insulation for High‐Temperature Applications

Aerogels owe their high thermal insulation and other unique properties to their nanostructure configuration. However, controlling the aerogels' morphology is always a scientific challenge. In this study, double dianhydride backbone (double backbone) polyimide aerogels with tailored nanostructure assembly are created for the first time. This is achieved by controlled polymerization reaction of oligomers with distinct dianhydride monomers. Combining the two oligomers through a controlled polymerization reaction is a successful strategy for tailoring the aerogels nanostructure assembly as well as other properties. The fabricated double backbone aerogel presents 40% reduced thermal conductivity of 19.7 mW mK^?1 over previously studied polyimide aerogels along with the compression modulus of 1.64 MPa at a relatively low density of 0.068 g cm^?3. Such low thermal conductivity is comparable with the inorganic counterparts. Light in weight and high thermally insulated polyimide aerogels with suitable mechanical properties and high service temperature are an appropriate replacement for current fireproof insulation materials.     

二氧化硅气凝胶的研究现状及应用前景

二氧化硅气凝胶由于其特殊的网络结构使其具有密度小、隔热性好、孔隙率高、比表面积大、传声速率低等优良性能。从1931年开始,经过广大研究者几十年的深入研究,二氧化硅气凝胶有了更广阔的发展。本文介绍了以不同原料制备二氧化硅气凝胶的方法,论述了二氧化硅气凝胶的干燥技术,概述了二氧化硅气凝胶的改性措施,分析了二氧化硅气凝胶的应用前景。     

House of Cards Nanostructuring of Graphene Oxide and Montmorillonite Clay for Oil–Water Separation

Noncovalent interactions are ubiquitous in our daily living. Nature employs hydrophobic effects, π–π interactions, hydrogen bonding, van der Waals forces, and electrostatic interactions in many biological processes such as protein folding. In the same manner, scientists exploit this plethora of inherently reversible noncovalent interactions as dials to design robust and smart materials. Electrostatic interaction is particularly interesting due to the simplicity of its concept, i.e., opposite charges attract. However, to our knowledge, the electrostatic interaction between two different 2D nanomaterials has not been investigated in literature. A myriad of natural and synthetic 2D nanomaterials should be explored for what may be an exciting cocktail of synergistic and tunable properties brought about by their charges and physical properties. This contribution highlights an interesting phenomena when organic, negatively charged graphene oxide and inorganic, positively charged montmorillonite (MMT) clay edges are brought into contact.     

Interpenetrated Networks of Nanocellulose and Polyacrylamide with Excellent Mechanical and Absorptive Properties

Composites based on interpenetrating networks (IPNs) of cellulose nanofibril (CNF) aerogels and polyacrylamide are prepared and exhibit robust mechanical, water retaining, and re‐swelling capacities. Furthermore, their swelling behavior is not affected by an increased ionic strength of the aqueous phase. These unprecedented IPNs combine the water retaining capacity of the polyacrylamide with the mechanical strength provided by the CNF aerogel template. The CNF aerogel/polyacrylamide composites exhibit a compressive stress at break greater than 250% compared with a neat polyacrylamide hydrogel. Furthermore, the composites retain their wet compression properties after drying and re‐swelling, whereas the neat polyacrylamide hydrogels fail at a significantly lower stress and strain after drying and re‐swelling. These composite materials highlight the potential of CNF aerogels to strengthen the mechanical properties and reduce the number of fracture defects during the drying and re‐swelling of a hydrogel. These composites show the potential of being optimized for a plethora of applications, especially in the hygiene field and for biomedical devices.     

酚醛气凝胶/碳纤维复合材料的结构调控及性能研究

以酚醛树脂为前体、碳纤维针刺预制体为增强体,采用溶胶-凝胶、常压干燥方法制备得到纳米孔酚醛气凝胶/碳纤维复合材料。在不改变材料密度的条件下,通过调节固化剂的用量来调控酚醛气凝胶的纳米颗粒尺寸及孔隙结构,改变气凝胶颗粒在碳纤维针刺预制体中的填充状态,制备出不同微观结构的复合材料。研究表明：随着固化剂用量的减少,气凝胶的颗粒粒径逐渐变小,平均孔径在230 nm~5μm范围内可调;与碳纤维复合后,随着气凝胶颗粒的减小,复合材料的力学性能逐渐提升、热导率逐渐降低、烧蚀性能明显提高。优化后的PAC复合材料具有极低的密度（0.27 g·cm^-3）、高弯曲强度（8.9 MPa）、较低的热导率（0.065 W·m^-1·K^-1）;在2000℃、30 s的中等热流烧蚀条件下,质量烧蚀率为0.0081 g·s^-1、线烧蚀率为0.0204 mm·s^-1。通过调控材料的纳米结构,能够有效地提升材料的力学、隔热以及烧蚀性能,满足高性能热防护应用需求。     

Effects of Eu content on the luminescent properties of Y2O3:Eu3+ aerogels and Y(OH)3/Y2O3:Eu3+@SiO2 glassy aerogels

This article describes the morphological, structural, and luminescent properties of Y₂O₃:Eu³⁺ aerogels and Y(OH)₃/Y₂O₃:Eu³⁺@SiO₂ glassy aerogels synthesized by the sol-gel method with Eu concentrations from 2.5 mol% to 30 mol%. XRD measurements indicated that both the aerogels and glassy aerogels had a monoclinic phase, but the crystallinity in the glassy aerogels was lower due to the presence of SiO₂. SEM images reveal that a three-dimensional porous network was formed in the aerogels due to the interconnection of coalesced Y₂O₃:Eu³⁺ nanoparticles. The 3D porous network was also observed in the glassy aerogels, coated with a silica shell. In both the aerogels and glassy aerogels, the size of the agglomerates decreased as the europium concentration increased. This, in turn, increased the average size of the macropores that formed their 3D network. Furthermore, the luminescent properties of the aerogels and glassy aerogels were studied under UV excitation, and it was observed that their red emission intensity increased continuously as the Eu³⁺ concentration increased. The luminescence of the aerogels was on average 50% higher than that of the glassy aerogels. Hence, our results indicate that porous and luminescent aerogels with and without silica are adequate for applications in sensing and catalysis.