Cellulose Silica Hybrid Nanofiber Aerogels: From Sol–Gel Electrospun Nanofibers to Multifunctional Aerogels

Abstract

Aerogels are considered ideal candidates for various applications, because of their low bulk density, highly porous nature, and functional performance. However, the time intensive nature of the complex fabrication process limits their potential application in various fields. Recently, incorporation of a fibrous network has resulted in production of aerogels with improved properties and functionalities. A facile approach is presented to fabricate hybrid sol-gel electrospun silica-cellulose diacetate (CDA)-based nanofibers to generate thermally and mechanically stable nanofiber aerogels. Thermal treatment results in gluing the silica-CDA network strongly together thereby enhancing aerogel mechanical stability and hydrophobicity without compromising their highly porous nature (>98%) and low bulk density (≈10 mg cm −3 ). X-ray photoelectron spectroscopy and in situ Fouriertransform infrared studies demonstrate the development of strong bonds between silica and the CDA network, which result in the fabrication of crosslinked structure responsible for their mechanical and thermal robustness and enhanced affinity for oils. Superhydrophobic nature and high oleophilicity of the hybrid aerogels enable them to be ideal candidates for oil spill cleaning, while their flame retardancy and low thermal conductivity can be explored in various applications requiring stability at high temperatures. and consists of a highly porous (at least 90%) solid network. [2] Their extremely low bulk density, highly porous nature, and large surface area make them ideal candidates for diverse applications ranging from thermal insulation, separation and biomedical to acoustics; [3][4][5][6] however, the time intensive nature of the fabrication process involving complicated steps and general lack of mechanical stability in the traditional aerogels present major challenges for their large scale applications in a cost-effective manner. Lack of flexibility and mechanical stability in an aerogel is primarily caused by the development of "necks" or "pearl-necklace like structure" during the drying process. [7] Introduction of polymeric phase in inorganic gels has helped to overcome this defect but the cost and duration of the process still hinder the large-scale application of these materials. Recent studies indicate that the presence of fibrous network in the aerogels strengthens it mechanically since it minimizes the existence of "necks" in the skeleton. [8][9][10][11][12] While exploring various options for functional fibrous networks, electrospun nanofibers can be considered as one of the leading options because of their fiber diameter in nanoscale, high aspect ratio and strength. [13,14] Electrospun nanofiber based materials demonstrate advanced properties; however, their layered deposition generates a 2D flat mat. [13,15] A 3D self-supportive structure would clearly further enhance the inherent properties of the nanofibers. Whereas techniques such as gas expansion, [16] cool drum, [17] and self-assembly [18,19] are explored to generate 3D nanofibr...

Plant celluloses, hemicelluloses, lignins, and volatile oils for the synthesis of nanoparticles and nanostructured materials

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A Remarkable Class of Nanocomposites: Aerogel Supported Bimetallic Nanoparticles

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A Review on Revolutionary Natural Biopolymer-Based Aerogels for Antibacterial Delivery

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