Cellulose最新文献

The increasing demand for sustainable and fire-safe textiles has motivated the development of eco-friendly flame-retardant systems. Herein, a fully bio-based flame-retardant was used to improve the flame retardancy of natural cellulosic flax fabric. For this purpose, two coating aqueous solutions including phytic acid (PA) and a clove plant-derived diamine (DA) with 5 and 10% (v/v) concentrates were used for the coating the surface of flax fabrics by a two and four-layer via hand dip-coating process. The results of the scanning electron microscopy (SEM) confirmed the uniform deposition of flame-retardant materials at each coating stage. The thermogravimetric analysis (TGA) revealed a significant enhancement in char residue upon coating. The coated flax fabrics demonstrated a remarkable enhancement in char residue, with PDPD10 (fabric with four layers of PA and DA in 10% concentration) reaching 48% at 800 °C, compared to only 18% for the uncoated fabric. The vertical flame test showed that all coated samples resisted ignition, as PDPD10 exhibited the best flame retardancy, the lowest char length of 7 cm, and no ignition. Pyrolysis-combustion flow calorimetry (PCFC) showed that the peak of heat release rate (pHRR) and total heat release (THR) were reduced by 94 and 91%, respectively, for the PDPD5 (fabric with four layers of PA and DA in 5% concentration), as compared to the pure fabric. The abrasion resistance of the coated flax fabrics significantly improved, with PDPD10 showing over 10,000 rubbing cycles, outperforming the untreated fabric, which lasted only 3200 cycles. The PDPD10 showed a remarkable improvement in tensile strength (40.83%), outperforming the uncoated fabric.

The poor barrier properties of paper restrict its use in packaging, particularly for applications requiring resistance to moisture and vapor. Polyhydroxybutyrate (PHB) is a microbial bio-polyester with excellent biodegradability, biocompatibility and hydrophobicity, offering a renewable alternative to petrochemical-based polymers. However, PHB’s insolubility in most solvents, with chloroform being the most effective, is a barrier to application. In this study we assess Cyrene™, a biodegradable green solvent, as an alternative to chloroform for dissolving and solvent-casting PHB onto paper. PHB (3% w/v) dissolved in chloroform at 50 °C formed a visually viscous, homogenous solution but at higher concentrations, solubility was reduced and coating lacked uniformity. In Cyrene™, PHB solubility was temperature-dependent: at 90 °C, it formed a cloudy but homogeneous solution while at 140 °C it was fully dissolved producing a clear, viscous solution, even at 5% (w/v). PHB-Cyrene™ solutions were compared with PHB-chloroform for casting onto Whatman filter paper 1. Optical profilometry and SEM showed smoother, more uniform PHB-Cyrene™ coatings, while FTIR confirmed PHB presence through the characteristic C=O (1720 cm⁻¹) peak. PHB coating imparted some oil resistance to papers. The water contact angle was highest for 3% PHB-Cyrene coated papers at 118° indicating excellent hydrophobicity. The water vapour permeability (WVP) performance of the 5% PHB-Cyrene™ coated paper (7.30 × 10⁻¹¹ g/Pa.s.m) was significantly (p = 0.0086) better than 5% PHB-chloroform (2.81 × 10⁻¹⁰ g/Pa.s.m), most likely due to more uniform coating, which also contributed to enhanced tensile strength. Cyrene™ is an effective and sustainable solvent for dissolving PHB and casting onto paper surfaces for sustainable packaging applications.

Cellulose-based hydrogels have attracted more and more attention in recent years. This study aimed to develop a biodegradable, dual-responsive cellulose-based hydrogel with sustained drug release properties. To achieve this goal, hydrogels with an interpenetrating-network structure based on cellulose derivatives with varying mass ratios were designed, and their controlled release properties for tetracycline hydrochloride (TH) were also investigated. First, carboxymethyl cellulose (CMC) was grafted onto hydroxypropyl cellulose (HPC) via a mediated reaction between N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodimide hydrochloride. Subsequently, an interpenetrating strategy was employed by introducing N-isopropylacrylamide (NIPAM) monomer as the second network through free radical polymerization into the preformed cellulose-based gel (HPC-co-CMC), thereby constructing a smart dual-network hydrogel (HPC-co-CMC/PNIPAM). The rheology tests, fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermal analysis, mechanical strength assessment, and drug loading capacity evaluations confirmed the stable formation of chemical cross-linking. The ratio of HPC to CMC had a significant effect on swelling capacity, TH release behavior, and antibacterial properties. In vitro studies, HPC-co-CMC/PNIPAM gels performed outstanding biocompatibility and antioxidant properties. The cumulative release behavior of TH indicated that an optimal HPC/CMC ratio could effectively prolong drug release time, and the dual-network HPC-co-CMC/PNIPAM hydrogels successfully prevented burst release. Furthermore, the pH/temperature-responsive behaviors were also evaluated through swelling ratio measurements. At a temperature of 37 °C and pH 5.0, the TH release rate reached its maximum cumulative release over 65 h. Therefore, HPC-co-CMC/PNIPAM gels have the great potential for advanced drug delivery applications.

Cellulose fibres are a sustainable alternative for development of new materials and with chemical modifications the material properties can be tailored for its intended application. To understand the impact of a modification characterisation techniques that reveal where the chemical alterations occur across the fibre are needed. Here we showcase how X-ray spectro-microscopy around the carbon K-edge can provide spatially resolved images of the chemical content of cellulose fibres and investigate the effect of different sample preparation strategies on the resulting data quality. We show that that one can spatially separate different lignin compositions over a single thermomechanical pulp fibre. The sample preparation is key for a successful experiment and requires sectioning of thin slices (~ 100 nm) of the sample which can be achieved by microtome sectioning. The effect of different embedding materials, including epoxies, cryo-embeddings with water and sucrose and elemental sulphur, is evaluated. The results show that epoxy embeddings are beneficial for homogenous sectioning, which is an advantage for imaging, while embedding strategies without carbon species, such as elemental sulphur or cryo-embedding with water, is better for evaluation of the chemical content in the fibre due to less overlap in the spectral signal from the embedding material. We also present measurement strategies for efficient data collection that minimise the inflicted radiation dose to provide guidelines for performing synchrotron-based spectro-microscopy around the carbon K-edge to characterise cellulose fibres.

This study presents a novel, eco-friendly approach for the synthesis of silicified microcrystalline cellulose (SMCC) from agricultural waste materials. Microcrystalline cellulose (MCC) was isolated from Screw Pine (SP) leaves, while sodium silicate was extracted from Mission Grass (MG) via alkali treatment. Silica sol was synthesised in situ through the hydrolysis of sodium silicate within the lacunae of the MCC, resulting in internally blended material. Two variants of SMCC, viz SMCC10 and SMCC20 were synthesized. Poly Vinyl Alcohol (PVA) films were produced by solution casting method using a customized hot and cold water soluble PVA blend. MCC, pure silica, SMCC10 and SMCC20 were used as fillers to assess and compare their influence on performance of composite film. SMCC20 based composite films with varying filler concentrations were also formulated and compared. The fillers and composites were characterized by XRD, FT-IR, TG, FE-SEM and UTM analysis. TGA revealed that SMCC exhibited 5.84% higher thermal stability than MCC, similarly for PVA/SMCC20 it was 5.32% higher than PVA. FE-SEM images showed that SMCC enabled more uniform filler dispersion compared to MCC and nano silica. Notably, PVA/SMCC film exhibited significant improvement in mechanical properties, with tensile strength increased by 37.2% and 38% upon the addition of SMCC10 and SMCC20 respectively. The results confirm that in situ silicification method enhances filler- matrix interaction and presents a greener substitute for conventional filler, underscoring SMCC’s potential in advanced biopolymer applications.

Graphical Abstract

Bacterial cellulose (BC) has emerged as a benchmark biopolymer for diverse industrial applications, particularly in biomedical, functional food, packaging, and cosmetic sectors. Its exceptional properties, including superior mechanical strength, thermal stability, chemical tunability, biocompatibility, biodegradability, and a highly porous nanofibrillar architecture, have further enabled its utilization in agriculture, environmental remediation, electronics, textiles, and paper industries. Despite its immense potential, widespread industrial adoption of BC faces a critical economic barrier: prohibitively high production costs. Key challenges include expensive culture media, low-efficiency microbial strains, suboptimal productivity rates, incomplete substrate utilization, and metabolic byproduct accumulation. Although contemporary strategies such as media optimization, genetic engineering, fermentation technology, and bioreactor design have improved yields, productivity, and profitability, achieving cost-competitive large-scale BC production remains an open challenge. A sustainable bioeconomic framework is presented here by developing a Block Flow Diagram (BFD) to valorize agro-industrial residues as low-cost substrates. Through the BFD analysis in a cohort with a comprehensive literature review of BC production optimization, standardized characterization, and innovative applications, this study evaluates progress toward techno-economic sustainability and identifies key areas for future improvements. The key insights from this research provide a roadmap for sustainable BC commercialization, emphasizing waste-derived feedstocks and process efficiency enhancements.

Ozone serves as a green oxidizing agent, and commonly employed in biomass refining processes. This study demonstrates a sustainable approach using ozone to regenerate periodate during natural fiber oxidation, simultaneously producing dialdehyde cellulose nanofibrils (CNFs) as value-added nanomaterials. The results showed that ozone molecules generated reactive oxygen species under alkaline conditions including hydroxyl radicals (∙OH), superoxide anions (∙O₂⁻), and hydroperoxyl radicals (∙HO₂⁻), which effectively oxidized iodate (IO₃⁻) to periodate (IO₄⁻). The optimal periodate regeneration yield (> 80% after 4 cycles) was achieved at pH 13 with 2.0 wt% ozone concentration for 30 min under ambient temperature conditions. In general, a synergistic strategy using ozone (2.0 wt%, 30 min) to simultaneously regenerate periodate and produce carboxylated CNFs was also elucidated with fiber oxidative degradation limited to < 16%. The obtained value-added carboxylated CNFs, with a carboxyl group content of approximately 1.2 mmol/g, exhibited excellent processability for fabricating functional biomaterial. The length of carboxylated CNFs generally exceeded 600 nm, and the average diameter was further reduced to 18.77 nm. The study indicated that the ozonation process can be effectively applied in oxidative refining of natural fibers, while significantly enhancing the added value of biomass resources.

In this study, nanocelluloses were successfully prepared from waste chestnut shells using three different methods: sulfuric acid hydrolysis (HCNC), enzymatic hydrolysis (ECNF), and TEMPO-mediated oxidation (TCNF). The yield, surface charge, chemical and crystalline structure, and thermal stability of the resulting nanocelluloses were comprehensively compared. HCNCs exhibited rod-like cellulose crystallite, whereas ECNFs and TCNFs displayed an entangled fibrous structure. HCNCs and TCNFs introduced anionic sulfate and carboxylic acid groups, respectively, while ECNFs preserved the natural surface properties of nanocellulose. The |zeta potential| of the nanocelluloses followed the order of TCNFs > HCNCs > ECNFs, while the crystallinity followed HCNCs > TCNFs > ECNFs, and thermal stability exhibited the reverse order of ECNFs > TCNFs > HCNCs. These differences can be attributed to variations in morphology and surface characteristics. This study presents a comparative analysis of various methods for converting chestnut shells into high value-added nanocellulose materials and explores the structural properties of these materials, thereby expanding the potential applications of nanocellulose across multiple fields.

In this work, dialdehyde cellulose microfibrils (DA-CMFs) were reacted with O-substituted hydroxylamines, demonstrating an effective and versatile method for lateral functionalization of DA-CMFs using mild, aqueous reaction conditions. Depending on the conditions used, partial or complete substitution of the aldehydes could be achieved. The reaction was performed in the presence and absence of the reducing agent α-picoline borane (PB). DA-CMFs were reacted with O-(carboxymethyl) hydroxylamine (HAAA), and the adhesive properties of native and HAAA-conjugated DA-CMFs to fibres were studied. The adhesive properties were shown to depend on charge; while native DA-CMFs aggregate heavily in contact with the fibre surface, HAAA-conjugated DA-CMFs showed significantly improved adhesion. For a degree of substitution of 50% or higher, a sealed layer, without aggregates, could be observed using electron microscopy. Finally, a versatile protocol for co-insertion of HAAA (carboxylate) and aminooxy-PEG₃-azide (hydroxylamine azide) was developed and demonstrated, with high yields of insertion. The modified DA-CMFs retained good adhesive properties to fibres, showing that the approach is general, and that the chemistry can be tuned depending on the target application.