Surface tailoring of cellulose aerogel-like structures with ultrathin coatings using molecular layer-by-layer assembly

Renewable biomass-based aerogels: from structural design to functional regulation

Global population growth and industrialization have exacerbated the nonrenewable energy crises and environmental issues, thereby stimulating an enormous demand for producing environmentally friendly materials. Typically, biomass-based aerogels (BAs), which are mainly composed of biomass materials, show great application prospects in various fields because of their exceptional properties such as biocompatibility, degradability, and renewability. To improve the performance of BAs to meet the usage requirements of different scenarios, a large number of innovative works in the past few decades have emphasized the importance of micro-structural design in regulating macroscopic functions. Inspired by the ubiquitous random or regularly arranged structures of materials in nature ranging from micro to meso and macro scales, constructing different microstructures often corresponds to completely different functions even with similar biomolecular compositions. This review focuses on the preparation process, design concepts, regulation methods, and the synergistic combination of chemical compositions and microstructures of BAs with different porous structures from the perspective of gel skeleton and pore structure. It not only comprehensively introduces the effect of various microstructures on the physical properties of BAs, but also analyzes their potential applications in the corresponding fields of thermal management, water treatment, atmospheric water harvesting, CO2 absorption, energy storage and conversion, electromagnetic interference (EMI) shielding, biological applications, etc. Finally, we provide our perspectives regarding the challenges and future opportunities of BAs. Overall, our goal is to provide researchers with a thorough understanding of the relationship between the microstructures and properties of BAs, supported by a comprehensive analysis of the available data.

Mechanical Properties of Cellulose Aerogel Composites with and without Crude Oil Filling

Aerogels are an excellent alternative to traditional oil absorbents and are designed to remove oil or organic solvents from water. Cellulose-based aerogels can be distinguished as polymers that are non-toxic, environmentally friendly, and biodegradable. The compression measurement properties of aerogels are often evaluated using dry samples. Here, oil-soaked, hydrophobized cellulose aerogel samples were examined in comparison to dry samples with and without additional hemp fibers and various levels of starch for crosslinking. The samples were characterized by compression measurement properties and filmed to evaluate the regeneration of the sorbent with repeated use. Overall, the measurements of the mechanical properties for the dry samples showed good reproducibility. The Young's modulus of samples with additional hemp fibers is significantly increased and also shows higher strength than samples without hemp fibers. However, samples without hemp fibers showed slightly better relaxation after compression. Oil acts as a weak plasticizer for all aerogel samples. However, it is important to note that the oil does not cause the samples to decompose in the way unmodified cellulose aerogels do in water. Therefore, using hydrophobized cellulose aerogels as sorbents for oil in a sea or harbor with swell means that they can be collected in their entirety even after use.

Advanced Functionalized Materials Based on Layer-by-Layer Assembled Natural Cellulose Nanofiber for Electrodes: A Review

The depletion of fossil fuel resources and its impact on the environment provide a compelling motivation for the development of sustainable energy sources to meet the increasing demand for energy. Accordingly, research and development of energy storage devices have emerged as a critical area of focus. The electrode materials are critical in the electrochemical performance of energy storage devices, such as energy storage capacity and cycle life. Cellulose nanofiber (CNF) represents an important substrate with potentials in the applications of green electrode materials due to their environmental sustainability and excellent compatibility. By utilizing the layer-by layer (LbL) process, well-defined nanoscale multilayer structure is prepared on a variety of substrates. In recent years, increasing attention has focused on electrode materials produced from LbL process on CNFs to yield electrodes with exceptional properties, such as high specific surface area, outstanding electrical conductivity, superior electrochemical activity, and exceptional mechanical stability. This review provides a comprehensive overview on the development of functional CNF via the LbL approach as electrode materials.

Incorporation of Cellulose-Based Aerogels into Textile Structures

Given their exceptional attributes, aerogels are viewed as a material with immense potential. Being a natural polymer, cellulose offers the advantage of being both replenishable and capable of breaking down naturally. Cellulose-derived aerogels encompass the replenish ability, biocompatible nature, and ability to degrade naturally inherent in cellulose, along with additional benefits like minimal weight, extensive porosity, and expansive specific surface area. Even with increasing appreciation and acceptance, the undiscovered possibilities of aerogels within the textiles sphere continue to be predominantly uninvestigated. In this context, we outline the latest advancements in the study of cellulose aerogels' formulation and their diverse impacts on textile formations. Drawing from the latest studies, we reviewed the materials used for the creation of various kinds of cellulose-focused aerogels and their properties, analytical techniques, and multiple functionalities in relation to textiles. This comprehensive analysis extensively covers the diverse strategies employed to enhance the multifunctionality of cellulose-based aerogels in the textiles industry. Additionally, we focused on the global market size of bio-derivative aerogels, companies in the industry producing goods, and prospects moving forward.

Preparation of high elastic bacterial cellulose aerogel through thermochemical vapor deposition catalyzed by solid acid for oil-water separation

Oil pollution has caused more and more serious damages to the environment, especially to water. Oil and water separation technologies based on high-performance absorbing materials have attracted extensive attentions. Herein, elasticity-enhanced bacterial cellulose (BC) aerogel is synthesized for oil/water separation through thermochemical vapor deposition (CVD) catalyzed by 1, 2, 3, 4-butanetetracarboxylic acid (BTCA). BTCA has two functions, namely, esterification with BC and catalyzing CVD. The prepared aerogel could be recovered soon after being compressed and the elastic recovery was >90 % at set maximum deformation of 80 %. And, it also exhibits vigorous fatigue resistance with an elastic deformation of >80 % after 50 cycles. The high elastic and hydrophobic aerogel is very suitable for absorbing and desorbing oils by simple mechanical squeezing. The adsorption capacity for n-hexane and dichloroethane maintain 87 % and 81 % after 50 cycles, respectively, which implies robust reusability. Importantly, the CVD could also be catalyzed by other solid acids such as citric acid and vitamin C. This design and fabrication method offers a novel avenue for the preparation of hydrophobic bacterial cellulose aerogel with high elasticity.

Steric Effects in the Deposition Mode and Drug-Delivering Efficiency of Nanocapsule-Based Multilayer Films

Using surface-initiated atom transfer radical polymerization (ATRP), block polymers with a series of quaternization degrees were coated on the surface of silica nanocapsules (SNCs) by the "grafting-from" technique. Molnupiravir, an antiviral medicine urgently approved for the treatment of SARS-CoV-2, was encapsulated in polymer-coated SNCs and further incorporated into well-defined films with polystyrene sulfonate (PSS) homopolymers by layer-by-layer (LBL) self-assembly via electrostatic interactions. We investigated the impact of the quaternization degree of the polymers and steric hindrance of functional groups on the growth mode, swelling/deswelling transition, and drug-delivering efficiency of the obtained LBL films. The SNCs were derived from coronas of parent block polymers of matched molecular weights-poly(N-isopropylacrylamide)-block-poly(N,N-dimethylaminoethyl methacrylate) (PNIPAM-b-PDMAEMA)-by quaternization with methyl sulfate. As revealed by the data results, SNCs with coronas with higher quaternization degrees resulted in a larger layering distance of the film structure because of weaker ionic pairing (due to the presence of a bulky methyl spacer) between SNCs and PSS. Interestingly, when comparing the drug release profile of the encapsulated drugs from SNC-based films, the release rate was slower in the case of capsule coronas with higher quaternization degrees because of the larger diffusion distance of the encapsulated drugs and stronger hydrophobic-hydrophobic interactions between SNCs and drug molecules.

Nitric oxide-releasing supramolecular cellulose nanocrystals/silsesquioxane foams

Cellulose nanocrystals (CNC)-based foams are promising tissue engineering materials that may facilitate implant-tissue integration and allow localized and controlled drug delivery. Herein, hybrid CNC-based foams, which are ultralightweight (30 to 100 mg cm^-3 ), highly porous (> 95%), ominiphilic and superabsorbent (1500 to 3000 wt% of water and/or toluene uptake) are obtained by the in-situ condensation of poly(ethylene glycol) ditriethoxysilyl (TES-PEG-TES) into a three-dimensional network, where silsesquioxane nanoparticles (SS-NP) are the cross-linking nodes, and CNC are entangled and forming ionic interactions, resulting in a supramolecular structure. In a new approach, using 3-mercaptopropyltrimethoxysilane, sulfhydryl groups are inserted on the SS-NP periphery and S-nitrosated to enable the functionalization of SS-NP with S-nitrosothiol groups, which are capable of releasing nitric oxide (NO), in a process triggered by the hydration of the foams and modulated by the supramolecular structure of the foams. CNC-SS-PEG foams exhibit elevated thermal and structural stability, compressive strength compatible with various soft human tissues, and NO release rates (1 - 18 pmol mg^-1 min^-1 ) within the range of the beneficial NO actions. Thus, the CNC-SS-PEG foams herein described represent a new platform of supramolecular hybrid materials for localized delivery of NO, with potential uses in tissue engineering and other biomedical applications. This article is protected by copyright. All rights reserved.