Surface modifications of cellulose nanocrystals: Processes, properties, and applications

Valorizing Biopolyester Suberin: Modification of Cellulose Nanocrystals and Performance Assessment in 3D-Printed Biobased Acrylates

Suberin, a common biomass processing waste, is a complex biopolymer and a promising source for the biorefinery of chemicals. Six different approaches for the extraction of birch outer bark suberin fatty acids (SFAs) were explored, and their application in grafting the surface of cellulose nanocrystals (CNCs) was investigated. Successful CNC functionalization was controlled with FTIR and NMR analyses. In-depth research allowed us to evaluate the interface of the nanocellulose and polymer matrix. Three structurally distinct SFA-grafted CNCs were integrated into a vegetable oil-based acrylate resin in an ultralow concentration of 0.1 wt %. Five biobased acrylic resin formulations were prepared: without reinforcement, with CNC, and with three distinct SFA-grafted CNCs. Vat photopolymerization (VP) 3D printing was utilized for sample preparation. The effects of grafted CNC components on 3D-printed samples' thermal stability, thermomechanical properties, and wettability were evaluated in detail. CNC functionalization enhanced the interface with the polymer matrix, yielding up to a 2-fold increase in elongation and up to a 2.5-fold increase in strength in tensile and flexural tests compared to the polymeric matrix. The CNC-SFA-modified filler demonstrated performance comparable to, or even better than, petroleum-based chemical modification routes found in the existing literature. This study highlights a promising approach for green functionalization of CNCs and verifies its use in interface enhancement using a biobased acrylate matrix.

Recent advances in nanocellulose pretreatment routes, developments, applications and future prospects: A state-of-the-art review

In a quest to find eco-friendly materials from renewable resources, researchers have focused on cellulose materials, which is the primary reinforcing component of plant cell walls. Nanocellulose is at the forefront of research due to its wide range of sources, biocompatibility, large surface area and tunable surface chemistry. It has gained considerable attention in various industries as a nano-reinforcement for polymer matrices due to its hierarchical structure (medical and healthcare, oil and gas, packaging, paper, board, composites, printed and flexible electronics, 3D printing, aerogels). In this paper, we have reviewed the recent advances in nanocellulose production, physical properties, structural characterization, surface modification strategies, pretreatment methods, applications, limitations and future directions. This review emphasizes the quantification of nanocellulose extraction and applications of the most prevalent areas of nanocellulose research. In view of its increasing and broader applications, the demand for nanocellulose is expected to increase in the future.

Sodium alginate-based indicator film with enhanced physicochemical properties induced by cellulose nanocrystals and monitor the freshness of chilled meat

Intelligent indicator films with colorimetric pH indicator properties were developed, incorporating black soybean seed coat anthocyanin (BA), cellulose nanocrystals (CNC), and sodium alginate (SA) to monitor meat freshness. The effect of different CNC additions on the microstructure, water barrier properties of the films, and BA release kinetics were comprehensively investigated. The results showed that with the increasement of CNC addition, the mechanical properties of SA/BA/CNC films were improved, the water contact angle significantly increased from 51.6° to 69°. Moreover, water solubility, vapor adsorption, and permeability significantly decreased, indicating enhanced water barrier properties. The release kinetic results showed that BA was released rapidly within 72 h and slowly thereafter, and its release process was described by Fick's model. Films with 7 % and 10 % CNC had lower BA diffusion coefficients. Their diffusions were formulated as linear regression equations (y = nx + a), where R2 was >0.80 and n was <0.50. Structural characterization showed that CNC immobilized BA mainly through hydrogen bonding, forming compact network microstructures with SA and BA. Meat freshness monitoring results showed that the film containing 7 % CNC showed visible color changes with increasing total volatile basic nitrogen and pH, along with low BA release, high water barrier and mechanical properties. Therefore, CNC has great potential for improving the physicochemical properties of indicator films, and the intelligent colorimetric indicator film could be applied to various food product.

Synthesis of bio-polyol-functionalized nanocrystalline celluloses as reactive/reinforcing components in bio-based polyurethane foams by homogeneous environment modification

Nanocrystalline Cellulose (NCC or CNC) is widely used as a filler in polymer composites due to its high specific strength, tensile modulus, aspect ratio, and sustainability. However, CNC hydrophilicity complicates its dispersion in hydrophobic polymeric matrices giving rise to aggregate structures and thus compromising its reinforcing action. CNC functionalization in a homogeneous environment, through silanization with trichloro(butyl)silane as a coupling agent and subsequent grafting with bio-based polyols, is herein investigated aiming to enhance CNC dispersibility improving the filler-matrix interaction between the hydrophobic PU and hydrophilic CNC. The modified CNCs (m_Ci) have been studied by XRD, SEM, and TGA analyses. The TGA results show that the amount of grafted polyol is strongly influenced by both its molar mass and OH number and the maximum amount of grafted polyol reaches up to 0.32 mmol per grams of functionalized CNC, within the explored conditions. The effect of different concentrations (1-3 wt%) of m_Ci on the physical, morphological, and mechanical properties of the resulting bio-based composite polyurethane foams is evaluated. Composite PU foams present compressive modulus up to 4.81 MPa and strength up to 255 kPa more than five times higher than those reinforced with unmodified CNC or with modified CNC in heterogeneous chemical environment. The improvement of mechanical properties of the examined PU foams, as a consequence of the incorporation of bio-polyols modified CNCs where polyol's OH groups interact with polyurethane precursors, could further broaden the use of these materials in building applications.

Efficient fabrication of cellulose polymer networks via alkaline swelling strategy for wood bonding

Existing issues with bio-based adhesives, such as complex preparation processes, high energy consumption, and production costs, still need to be addressed. In our study, APTES was grafted onto microcrystalline cellulose (MCC) to generate active aminated cellulose, and then reacted with the epoxide group in glycerol triglycidyl ether (GTE) through a swelling strategy under alkaline solvent, forming a network structure via covalent cross-linking. The adhesive exhibits superior bonding performance and water-resistant property in the bonding strength test of poplar plywood, with a dry shear strength of 2.40 MPa, a wet shear strength of 2.16 MPa after soaking in 63 °C hot water, and a wet shear strength of 1.79 MPa after soaking in boiling water. In terms of cost calculation, the theoretical production cost of AC-GTE adhesive is calculated to be 5303.7 RMB per ton, which is comparable to that of phenol-formaldehyde (PF) resin and other petrochemical-based adhesives, and significantly lower than that of isocyanate-based adhesives. These research results can provide a practical example for producing high-efficiency, aldehyde-free, and low-cost bio-based adhesives.

Lignin-containing cellulose nanocrystals from maple leaves: A natural Pickering emulsion stabilizer for food preservation

Cellulose nanocrystals have been obtained from maple leaves for stabilizing Pickering emulsions, but a chemical modification is required to improve hydrophobicity and the yield is relatively low due to the removal of non-cellulose components. Herein, lignin was retained while isolating cellulose from maple leaves, and the prepared lignin-containing cellulose nanocrystals (LCNCs) were applied as natural Pickering emulsion stabilizers. Rod-like shaped LCNCs with tunable lignin contents had suitable hydrophobicity and high aspect ratios, resulting in long-term stability of LCNC-stabilized Pickering emulsions. The obtained emulsions provided good encapsulation and protection of cinnamaldehyde, and the controlled release of cinnamaldehyde promoted sustained antibacterial efficacy. Both direct-contact and non-contact preservation modes were investigated for shrimp preservation, where headspace release of cinnamaldehyde from emulsions at non-contact mode was more effective in inhibiting bacterial proliferation compared to direct-contact (spray-coating) mode. This work demonstrates the feasibility of developing value-added LCNCs from maple leaves as sustainable Pickering emulsion stabilizers.

Stimuli-Responsive Chiral Cellulose Nanocrystals Based Self-Assemblies for Security Measures to Prevent Counterfeiting: A Review

The proliferation of misleading information and counterfeit products in conjunction with technical progress presents substantial worldwide issues. To address the issue of counterfeiting, many tactics, such as the use of luminous anticounterfeiting systems, have been investigated. Nevertheless, traditional fluorescent compounds have a restricted effectiveness. Cellulose nanocrystals (CNCs), known for their renewable nature and outstanding qualities, present an excellent opportunity to develop intelligent, optically active materials formed due to their self-assembly behavior and stimuli response. CNCs and their derivatives-based self-assemblies allow for the creation of adaptable luminous materials that may be used to prevent counterfeiting. These materials integrate the photophysical characteristics of optically active components due to their stimuli-responsive behavior, enabling their use in fibers, labels, films, hydrogels, and inks. Despite substantial attention, existing materials frequently fall short of practical criteria due to limited knowledge and poor performance comparisons. This review aims to provide information on the latest developments in anticounterfeit materials based on stimuli-responsive CNCs and derivatives. It also includes the scope of artificial intelligence (AI) in the near future. It will emphasize the potential uses of these materials and encourage future investigation in this rapidly growing area of study.

Obtention and Characterization of Microcrystalline Cellulose from Industrial Melon Residues Following a Biorefinery Approach

Residual melon by-products were explored for the first time as a bioresource of microcrystalline cellulose (MCC) obtention. Two alkaline extraction methods were employed, the traditional (4.5% NaOH, 2 h, 80 °C) and a thermo-alkaline in the autoclave (2% NaOH, 1 h, 100 °C), obtaining a yield of MCC ranging from 4.76 to 9.15% and 2.32 to 3.29%, respectively. The final MCCs were characterized for their chemical groups by Fourier-transform infrared spectroscopy (FTIR), crystallinity with X-ray diffraction, and morphology analyzed by scanning electron microscope (SEM). FTIR spectra showed that the traditional protocol allows for a more effective hemicellulose and lignin removal from the melon residues than the thermo-alkaline process. The degree of crystallinity of MCC ranged from 51.51 to 61.94% and 54.80 to 55.07% for the thermo-alkaline and traditional processes, respectively. The peaks detected in X-ray diffraction patterns indicated the presence of Type I cellulose. SEM analysis revealed microcrystals with rough surfaces and great porosity, which could remark their high-water absorption capacity and drug-carrier capacities. Thus, these findings could respond to the need to valorize industrial melon by-products as raw materials for MCC obtention with potential applications as biodegradable materials.

Development of nanocellulose hydrogels for application in the food and biomedical industries: A review

As the most abundant and renewable natural resource, cellulose has attracted significant attention and research interest for the production of hydrogels (HGs). To address environmental issues and emerging demands, the benefits of naturally produced HGs include excellent mechanical properties and superior biocompatibility. HGs are three-dimensional networks created by chemical or physical cross-linking of linear or branched hydrophilic polymers and have high capacity for absorption of water and biological fluids. Although widely used in the food and biomedical fields, most HGs are not biodegradable. Nanocellulose hydrogels (NC-HGs) have been extensively applied in the food industry for detection of freshness, chemical additives, and substitutes, as well as the biomedical field for use as bioengineering scaffolds and drug delivery systems owing to structural interchangeability and stimuli-responsive properties. In this review article, the sources, structures, and preparation methods of NC-HGs are described, applications in the food and biomedical industries are summarized, and current limitations and future trends are discussed.

Biosafety consideration of nanocellulose in biomedical applications: A review

Nanocellulose-based biomaterials have gained significant attention in various fields, especially in medical and pharmaceutical areas, due to their unique properties, including non-toxicity, high specific surface area, biodegradability, biocompatibility, and abundant feasible and sophisticated strategies for functional modification. The biosafety of nanocellulose itself is a prerequisite to ensure the safe and effective application of biomaterials as they interact with living cells, tissues, and organs at the nanoscale. Potential residual endogenous impurities and exogenous contaminants could lead to the failure of the intended functionalities or even serious health complications if they are not adequately removed and assessed before use. This review summarizes the sources of impurities in nanocellulose that may pose potential hazards to their biosafety, including endogenous impurities that co-exist in the cellulosic raw materials themselves and exogenous contaminants caused by external exposure. Strategies to reduce or completely remove these impurities are outlined and classified as chemical, physical, biological, and combined methods. Additionally, key points that require careful consideration in the interpretation of the biosafety evaluation outcomes were discussed to ensure the safety and effectiveness of the nanocellulose-based biomaterials in medical applications.

Silver nanoparticles coated cellulose-based flexible membrane with excellent UV resistance, high infrared reflection and water resistance for personal thermal management

Designing of a green and multifunctionally integrated cellulose-based flexible wearable material with personal thermoregulation, water and ultraviolet (UV) resistance is essential for the development of personal thermal management and smart textiles. Herein, a hydrophobic silver nanoparticles cellulose-based membrane (H-AgNPs/CEPCM) was prepared through simple solution blending, spin-coating process and chemical vapor modification. The prepared membrane exhibited excellent UV resistance due to the synergistic effect of carbon quantum dots (CQDs) as well as UV-absorbing functional groups. The spin-coated AgNPs layer with high infrared reflectivity has great radiant insulation, and temperature was reduced by 3.4 °C compared with H-CEPCM in indoor environment. Furthermore, the mechanical properties of H-AgNPs/CEPCM were significantly improved by the introduction of amide and ether bonds, as well as a large number of hydrogen bonds. This led to a tensile strength of 23.21 MPa and an elongation at break of 16.57 %, while also providing water resistance. Additionally, the H-AgNPs/CEPCM exhibited outstanding thermal stability and hydrophobicity. This work may provide a feasible and promising strategy for the construction of multifunctional integrated cellulose membrane materials for radiant insulation, outdoor textiles and novel UV protection applications.

Recent Advances in Flexible CNC-Based Chiral Nematic Film Materials

Cellulose nanocrystal (CNC) is a renewable resource derived from lignocellulosic materials, known for its optical permeability, biocompatibility, and unique self-assembly properties. Recent years have seen great progresses in cellulose nanocrystal-based chiral photonic materials. However, due to its inherent brittleness, cellulose nanocrystal shows limitations in the fields of flexible materials, optical sensors and food freshness testing. In order to solve the above limitations, attempts have been made to improve the flexibility of cellulose nanocrystal materials without destroying their structural color. Despite these progresses, a systematic review on them is lacking. This review aims to fill this gap by providing an overview of the main strategies and the latest research findings on the flexibilization of cellulose nanocrystal-based chiral nematic film materials (FCNM). Specifically, typical substances and methods used for their preparation are summarized. Moreover, different kinds of cellulose nanocrystal-based composites are compared in terms of flexibility. Finally, potential applications and future challenges of flexible cellulose nanocrystal-based chiral nematic materials are discussed, inspiring further research in this field.

Modified Biomass-Reinforced Polylactic Acid Composites

Polylactic acid (PLA), as a renewable and biodegradable green polymer material, is hailed as one of the most promising biopolymers capable of replacing petroleum-derived polymers for industrial applications. Nevertheless, its limited toughness, thermal stability, and barrier properties have restricted its extensive application. To address these drawbacks in PLA, research efforts have primarily focused on enhancing its properties through copolymerization, blending, and plasticization. Notably, the blending of modified biomass with PLA is expected not only to effectively improve its deficiencies but also to maintain its biodegradability, creating a fully green composite with substantial developmental prospects. This review provides a comprehensive overview of modified biomass-reinforced PLA, with an emphasis on the improvements in PLA's mechanical properties, thermal stability, and barrier properties achieved through modified cellulose, lignin, and starch. At the end of the article, a brief exploration of plasma modification of biomass is presented and provides a promising outlook for the application of reinforced PLA composite materials in the future. This review provides valuable insights regarding the path towards enhancing PLA.

Unveiling the interactions between biomaterials and heterocyclic dyes: A sustainable approach for wastewater treatment

The present Review investigates the interactions between biomaterials and heterocyclic dyes, focusing on their potential application in sustainable wastewater treatment. Heterocyclic dyes are widely used in various industries, resulting in their widespread presence in wastewater, posing environmental challenges. This review explores the utilization of biomaterials as adsorbents for the removal of heterocyclic dyes from contaminated water sources. The interactions between biomaterials, such as cellulose, microfibrilated cellulose and lignin and different heterocyclic dyes are examined through reported experimental analysis and characterization techniques. The study evaluates the adsorption capacity, kinetics, and thermodynamics of the biomaterial-dye systems to elucidate the underlying mechanisms and optimize the treatment process. The review highlight the promising potential of biomaterial-based approaches for sustainable wastewater treatment, providing insights for the development of efficient and environmentally friendly dye removal technologies.

Biopolymer-Based Nanosystems: Potential Novel Carriers for Kidney Drug Delivery

Kidney disease has become a serious public health problem throughout the world, and its treatment and management constitute a huge global economic burden. Currently, the main clinical treatments are not sufficient to cure kidney diseases. During its development, nanotechnology has shown unprecedented potential for application to kidney diseases. However, nanotechnology has disadvantages such as high cost and poor bioavailability. In contrast, biopolymers are not only widely available but also highly bioavailable. Therefore, biopolymer-based nanosystems offer new promising solutions for the treatment of kidney diseases. This paper reviews the biopolymer-based nanosystems that have been used for renal diseases and describes strategies for the specific, targeted delivery of drugs to the kidney as well as the physicochemical properties of the nanoparticles that affect the targeting success.

Microbial Synthesis of Lactic Acid from Cotton Stalk for Polylactic Acid Production

Cotton stalk, a waste product in agriculture, serves as a beneficial, low-cost material as a medium for microbial synthesis of lactic acid as desired for polylactic acid synthesis. Cotton stalk was used as a substrate for microbial lactic acid synthesis, and a novel strain of Lactococcus cremoris was reported to synthesize 51.4 g/L lactic acid using cellulose recovered from the cotton stalk. In total, 18 Lactobacillus isolates were isolated from kitchen waste, soil, sugarcane waste, and raw milk samples screened for maximum lactic acid production. It was found that one of the Lactococcus cremoris isolates was found to synthesize maximum lactic acid at a concentration of 51.4 g/L lactic acid in the hydrolysate prepared from cotton stalk. The upstream process parameters included 10% inoculum size, hydrolysate containing reducing sugars 74.23 g/L, temperature 37 °C, agitation 220 rpm, production age 24 h. Only the racemic (50:50) mixture of D-LA and L-LA (i.e., D/L-LA) is produced during the chemical synthesis of lactic acid, which is undesirable for the food, beverage, pharmaceutical, and biomedical industries because only the L-form is digestible and is not suitable for biopolymer, i.e., PLA-based industry where high optically purified lactic acid is required. Furthermore, polylactic acid was synthesized through direct polycondensation methods using various catalysts such as chitosan, YSZ, and Sb2O3. PLA is biocompatible and biodegradable in nature (its blends and biocomposites), supporting a low-carbon and circular bioeconomy.

Extraction and Surface Functionalization of Cellulose Nanocrystals from Sugarcane Bagasse

The present study aimed to optimize the process for extracting cellulose nanocrystals (CNCs) from sugarcane bagasse through ultrasonic-assisted sulfuric acid hydrolysis and its subsequent modification with L-malic acid and silane coupling agent KH-550. The effects of the different modification methods and the order of modification on the structures and properties of bagasse CNCs were explored. The results indicated that the optimal process conditions were achieved at an acid-digestion temperature of 50 °C, a reaction time of 70 min, an ultrasonic power of 250 W, and a volume fraction of 55%. The modified CNCs were analyzed using infrared spectral, X-ray diffraction, and thermogravimetric techniques, which revealed that L-malic acid was attached to the hydroxyl group on the CNCs via ester bond formations, and the silane coupling agent KH-550 was adsorbed effectively on the CNCs' surfaces. Moreover, it was observed that the modification of the CNCs by L-malic acid and the KH-550 silane coupling agent occurred only on the surface, and the esterification-crosslinking modification method provided the best thermal stability. The performance of self-made CNC was found to be superior to that of purchased CNC based on the transmission electron microscopy analysis. Furthermore, the modified esterified-crosslinked CNCs exhibited the best structure and performance, thereby offering a potential avenue for the high-value utilization of sugarcane bagasse, a byproduct of sugarcane sugar production, and the expansion of the comprehensive utilization of sugarcane bagasse.

Effects of carboxymethyl cellulose on the emulsifying, gel and digestive properties of myofibrillar protein-soybean oil emulsion

Improving the qualities of vegetable oil replaced animal fat meat products is particularly fascinating for the development of healthy meat products. This work was designed to investigate the effects of different carboxymethyl cellulose (CMC) concentrations (0.01 %, 0.05 %, 0.1 %, 0.2 %, and 0.5 %) on the emulsifying, gelation, and digestive properties of myofibrillar protein (MP)-soybean oil emulsions. The changes in MP emulsion characteristics, gelation properties, protein digestibility, and oil release rate were determined. Results demonstrated that CMC addition decreased the average droplet size and increased the apparent viscosity, storage modulus, and loss modulus of MP emulsions, and a 0.5 % CMC addition significantly increased the storage stability during 6 weeks. Lower CMC addition (0.01 % to 0.1 %) increased the hardness, chewiness, and gumminess of emulsion gel especially for the 0.1 % CMC addition, while higher CMC (0.5 %) content decreased the texture properties and water holding capacity of emulsion gels. The addition of CMC decreased protein digestibility during the gastric stage, and 0.01 % and 0.05 % CMC addition significantly decreased the free fatty acid release rate. In summary, the addition of CMC could improve the stability of MP emulsion and the texture properties of the emulsion gels, and decrease protein digestibility during the gastric stage.

Production of a nascent cellulosic material from vegetable waste: Synthesis, characterization, functional properties, and its potency for a cationic dye removal

The present work reports the production of cellulose nanocrystals, CNC₃₀ and CNC₆₀, developed using vegetable waste, i.e., bottle gourd peel through sulfuric acid hydrolysis with a 30 and 60 min hydrolysis process coupled with ultrasonication. The FTIR confirmed the absence of hemicellulose and lignin, and XRD confirmed the crystallinity of the cellulose nanocrystals. DLS studies indicated the hydrodynamic diameter of CNC₃₀ and CNC₆₀ to be 195.5 nm and 192.2 nm, respectively. The TEM image and SAED pattern established the shape of CNC₆₀ to be spherical, with an average particle size of 38.32 nm. CNC₆₀ possessed lesser negative potential and higher thermal stability than CNC₃₀, possibly due to the demolition of the crystalline regions containing sulfate groups. The functional properties, such as swelling power, water, and oil holding capacities of CNC₆₀, were superior to that of CNC₃₀. The adsorption batch parameters yielded 95.68 % methylene dye removal by CNC₆₀ against the predicted value of 96.16 % by the RSM-PSO hybrid approach. The analyses of adsorption isotherms, kinetics, and thermodynamic parameters revealed the nature of the adsorbed layer and adsorption mechanism. Overall observations recommend that CNC₆₀ could be a good and potent functional agent in paper technology, food technology, water treatment, and biomedical applications.

Gamma irradiation induced surface modification of (PVC/HDPE)/ZnO nanocomposite for enhancing the oil removal and conductivity using COMSOL multiphysics

Blend nanocomposite film was prepared by loadings of irradiated ZnO in ratios of (5 wt%) inside the PVC/HDPE matrix using a hot-melt extruder technique. The physical and chemical properties of the irradiated and unirradiated ZnO samples are compared. The Vis-UV spectrum of ZnO shows an absorption peak at a wavelength of 373 nm that was slightly red-shifted to 375 nm for an irradiated sample of ZnO at a dose of 25 kGy due to the defect of crystal structure by the oxygen vacancy during gamma irradiations. This growth of the defect site leads to a decrease in energy gaps from 3.8 to 2.08 eV. AC conductivity of ZnO sample increased after the gamma irradiation process (25 kGy). The (PVC/HDPE)/ZnO nanocomposites were re-irradiated with γ rays at 25 kGy in the presence of four different media (silicon oil, sodium silicate, paraffin wax and water). FTIR and XRD were performed to monitor the changes in chemical composition. The new peak at 1723 cm^-1 attributed to C=O groups was observed in irradiated (PVC/HDPE)ZnO samples at only sodium silicate and water media. This process induced new function groups on the surface of the (PVC/HDPE)/ZnO blend sample. This work aims to develop (PVC/HDPE)ZnO for oil/water separation. The highest oil adsorption capability was observed in samples functionalized by C=O groups based on the different tested oils. The results suggest that the surface characterization of the (PVC/HDPE)/ZnO can be modified to enhance the oil adsorption potential. Further, the gamma irradiation dose significantly enhanced the AC conductivity compared to the unirradiated sample. According to COMSOL Multiphysics, the irradiated sample (PVC/HDPE)ZnO in water shows perfect uniform electric field distribution in medium voltage cables (22.000 V).

Chitosan particles modulate the properties of cellulose nanocrystals through interparticle interactions: Effect of concentration

The physical and chemical properties of cellulose nanocrystals (CNC) were regulated by physical crosslinking with chitosan particles (CSp). At a fixed concentration (0.5 wt%) of CNC, varying CSp concentration (0.02-0.5 wt%) influenced the morphologies and chemical properties of the obtained complex particles (CNC-CSp). The results of Fourier transform infrared spectroscopy (FTIR) and zeta potential confirmed the electrostatic and hydrogen bonding interactions between CSp and CNC. At a low CSp concentration (0.02-0.05 wt%), the charge shielding effect induced the formation of particle aggregation networks, thus showing increased viscosity, turbidity and size (153.4-2605.7 nm). At a higher CSp concentration (0.1-0.5 wt%), the hydrogen bonding interaction promoted CSp adsorption onto the surface of CNC, thus facilitating the dispersion of CNC-CSp due to electrostatic repulsion caused by surface-adsorbed CSp. In addition, CSp improved the thermal stability, hydrophobicity (41.87-60.02°) and rheological properties of CNC. Compared with CNC, CNC-CSp displayed a better emulsifying ability and emulsion stability, in which CSp could play a dual role (i.e., charge regulator and stabilizer). This study suggests that introducing CSp can improve the properties and application potentials of CNC as food colloids.

Challenges associated with cellulose composite material: Facet engineering and prospective

Cellulose is the most abundant polysaccharide on earth. It has a large number of desirable properties. Its low toxicity makes it more useful for a variety of applications. Nowadays, its composites are used in most engineering fields. Composite consists of a polymer matrix and use as a reinforcing material. By reducing the cost of traditional fibers, it has an increasing demand for environment-friendly purposes. The use of these types of composites is inherent in moisture absorption with hindered natural fibers. This determines the reduction of polymer composite material. By appropriate chemical surface treatment of cellulose composite materials, the effect could be diminished. The most modern and advanced techniques and methods for the preparation of cellulose and polymer composites are discussed here. Cellulosic composites show a reinforcing effect on the polymer matrix as pointed out by mechanical characterization. Researchers tried their hard work to study different ways of converting various agricultural by-products into useful eco-friendly polymer composites for sustainable production. Cellulose plays building blocks, that are critical for polymer products and their engineering applications. The most common method used to prepare composites is in-situ polymerization. This help to increase the yields of cellulosic composites with a significant enhancement in thermal stability and mechanical properties. Recently, cellulose composites used as enhancing the incorporation of inorganic materials in multi-functional properties. Furthermore, we have summarized in this review the potential applications of cellulose composites in different fields like packaging, aerogels, hydrogels, and fibers.

Surface engineering on cholesteric cellulose nanocrystals films inducing emulsification, organic pollutants detection and separation

Nowadays, organic pollutants have been major concerns in many fields. Production of functional materials based on renewable and sustainable resources for organic pollutants detection and removal was of much interest. Herein, multi-functional nanocomposite films based on cellulose nanocrystals (CNCs) with high optical haze, organic pollutant detection and emulsion separation capabilities, have been successfully fabricated based on hydrophobically-modified CNCs suspensions by 2-dodecen-1-succinic anhydride (DDSA) followed by radical polymerization with tridecafluorooctyl (TFMA). The suspensions displayed satisfying oil-in-water emulsion stabilization capabilities and the vacuum-dried films showed birefringence, high transparency, and optical haze (~85 %), due to the ordered arrangements of cellulose nanocrystals. The organic pollutant can be detected through the iridescent colors disappearing by Polarizing Optical Microscope observation. In addition of improved mechanical strength for application (27 MPa) and high contact angle of 131.6°, the hydrophobic films performed as high separation efficiency as >90 % of emulsion, due to the successfully grafting of hydrophobic molecules on the surface of CNCs. Thus, the surface modification for CNCs provide a facile approach of emulsification, pollutants detection and separation properties, which would widen the application potentials of renewable cellulosic resources in fields of environmental protection, engineering control and petroleum industry.

Thermoresponsive nanofibers loaded with antimicrobial α-aminophosphonate-o/w emulsion supported by cellulose nanocrystals for smart wound care patches

Long-term topical application of antibiotics on wounds has led to the emergence of drug-resistant bacterial infections. Antibiotic incorporation into the wound dressing requires enormous advancement of the field to ensure that the needed dose is released when the infection arises. This study synthesized a series of antimicrobial α-aminophosphonate derivatives, and the most effective compound was incorporated into thermoresponsive wound dressing patches. Wound dressing mats were fabricated by needleless electrospinning, and the resultant nanofiber mats were coated with a thermoresponsive eicosane/cellulose nanocrystals o/w system loaded with active α-aminophosphonate derivatives. Chemical, physical, thermal, and antimicrobial properties of the wound dressings were characterized wound dressings. Using SEM analysis, Nanofibers spun with 20 % w/v solutions were selected for drug-emulsion loading since they showed lower diameters with higher surface area. Furthermore, the drug-emulsion coating on the electrospun dressings improved the hydrophilicity of the wound dressings, and the thermoresponsive behavior of the mats was proved using differential scanning calorimetry data. Finally, the drug-loaded electrospun meshes were found active against tested microorganisms, and clear inhibition zones were observed. In conclusion, this novel approach of synthesizing a new family of antimicrobial molecules and their incorporation into nanofibers from renewable sources exhibits great potential for smart and innovative dressings.

Preparation of Cellulose Nanocrystals by Synergistic Action of Ionic Liquid and Recyclable Solid Acid under Mild Conditions

Cellulose nanocrystals (CNCs) are nanoscale particles made from cellulose. They have many unique properties such as being lightweight, stiff, and renewable, making them promising for a variety of applications in a wide range of industries, including materials science, energy storage, and biomedicine. In this paper, a two-stage (swelling-SA-catalyzed) method including IL pretreatment and solid acid hydrolysis process was developed to extract CNCs with high purity and good thermal stability from microcrystalline cellulose (MCC). In the first stage, the swelling of MCC in ionic liquid was studied with the assistance of ultrasonication, and it was found that the amorphous regions became more disordered while the crystalline areas were selectively retained under the conditions of 30 min of reaction time, 45 °C of temperature, 2% of ionic liquid water content and 1:4 mass ratio of cellulose to ionic liquid. CNCs were extracted using solid acid hydrolysis, with a 45 wt% solid acid to cellulose ratio and a 5.0 h hydrolysis process at 45 °C. The morphology, crystallinity, surface characteristics and thermo stability of the sample were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. Results demonstrated the highly thermostable CNCs were successful extracted with rodlike shape of 300 ± 100 nm in length and 20 ± 10 nm in width. Solid acid recovery and reuse were also studied, revealing a promising candidate that can reduce the environmental impact associated with chemical products.

Rice thermoplastic starch nanocomposite films reinforced with nanocellulose

Rice starch is a raw material with proven potential in obtaining biodegradable polymers. Plasticization improves the flexibility characteristics of starch-based films, although they still tend to have low tensile strength and high hydrophilicity. The addition of nanocellulosic materials is an alternative to improve these characteristics. In this chapter, the effects of adding different sources and concentrations of nanocellulose (NC) on the properties of thermoplastic rice starch films (TRSF) are addressed. One can highlight as main effects the increase of tensile strength and transparency of the films, the reduction of water vapor permeability and water solubility. The type of NC used, the way it is obtained, as well as its interaction with starch molecules are factors that influence the effects. Further studies involving the interaction of TRSF and NC should be conducted in order to overcome the lack of information.

Effect of the Addition of Corn Husk Cellulose Nanocrystals in the Development of a Novel Edible Film

The cellulose from agroindustrial waste can be treated and converted into nanocrystals or nanofibers. It could be used to produce biodegradable and edible films, contributing to the circular economy and being environmentally friendly. This research aimed to develop an edible film elaborated with activated cellulose nanocrystals, native potato starch, and glycerin. The activated cellulose nanocrystals were obtained by basic/acid digestion and esterification with citric acid from corn husks. The starch was extracted from the native potato cultivated at 3500 m of altitude. Four film formulations were elaborated with potato starch (2.6 to 4.4%), cellulose nanocrystals (0.0 to 0.12%), and glycerin (3.0 to 4.2%), by thermoforming at 60 °C. It was observed that the cellulose nanocrystals reported an average size of 676.0 nm. The films mainly present hydroxyl, carbonyl, and carboxyl groups that stabilize the polymeric matrix. It was observed that the addition of cellulose nanocrystals in the films significantly increased (p-value < 0.05) water activity (0.409 to 0.447), whiteness index (96.92 to 97.27), and organic carbon content. In opposition to gelatinization temperature (156.7 to 150.1 °C), transparency (6.69 to 6.17), resistance to traction (22.29 to 14.33 N/mm), and solubility in acidic, basic, ethanol, and water media decreased. However, no significant differences were observed in the thermal decomposition of the films evaluated through TGA analysis. The addition of cellulose nanocrystals in the films gives it good mechanical and thermal resistance qualities, with low solubility, making it a potential food-coating material.

A fungal cellulose nanocrystals-based approach to improve the stability of triterpenes loaded Pickering emulsion

Depolysaccharide residues of edible fungus Pleurotus eryngii (dePSR-Pe), a mushroom industry waste, have abundant cellulose. In this study, the cellulose nanocrystals of P. eryngii (PeCNs) were extracted by hydrochloric acid. Results showed that the length of PeCNs is 469 ± 76.41 nm with a high aspect ratio of 40-100 and needle morphology. The structural characterization revealed that PeCNs had good thermal stability (approach 300 °C) and high crystallinity (84.2 %). An O/W Pickering emulsion stabilized with PeCNs was prepared to inhibit lipid oxidation and improve the loading capacity of triterpenes of P. coco. Unimodal size distribution of emulsion droplets was obtained under an optimized aqueous-phase condition to form a metastable emulsion, regardless of varying oil-water volume ratio <50/50. In vitro digestion study suggested that triterpenes-loaded Pickering emulsion had 1-3 times higher drug stability than bulk oil. These metastable Pickering emulsions call for fewer nanoparticles and provide a new strategy for the industry application of cellulose nanocrystals at less cost.

Source of Nanocellulose and Its Application in Nanocomposite Packaging Material: A Review

Food packaging nowadays is not only essential to preserve food from being contaminated and damaged, but also to comply with science develop and technology advances. New functional packaging materials with degradable features will become a hot spot in the future. By far, plastic is the most common packaging material, but plastic waste has caused immeasurable damage to the environment. Cellulose known as a kind of material with large output, wide range sources, and biodegradable features has gotten more and more attention. Cellulose-based materials possess better degradability compared with traditional packaging materials. With such advantages above, cellulose was gradually introduced into packaging field. It is vital to make packaging materials achieve protection, storage, transportation, market, and other functions in the circulation process. In addition, it satisfied the practical value such as convenient sale and environmental protection, reduced cost and maximized sales profit. This review introduces the cellulose resource and its application in composite packaging materials, antibacterial active packaging materials, and intelligent packaging materials. Subsequently, sustainable packaging and its improvement for packaging applications were introduced. Finally, the future challenges and possible solution were provided for future development of cellulose-based composite packaging materials.

Cellulose nanocrystals based delivery vehicles for anticancer agent curcumin

Cancer is a complex disease that starts with genetic alterations and mutations in healthy cells. The past decade has witnessed a huge demand for new biocompatibility and high-performance intelligent drug delivery systems. Curcumin (CUR) is a bioactive stimulant with numerous medical benefits. However, because of its hydrophobic nature, it has low bioavailability. The utilization of many biobased materials has been found to improve the loading of hydrophobic drugs. Cellulose nanocrystals (CNCs) with exceptional qualities and a wide range of applications, feature strong hydrophilicity and lipophilicity, great emulsification stability, high crystallinity and outstanding mechanical attributes. In this review, numerous CNCs-based composites have been evaluated for involvement in the controlled release of CUR. The first part of the review deals with recent advancements in the extraction of CNCs from lignocellulose biomass. The second elaborates some recent developments in the post-processing of CNCs in conjunction with other materials like natural polymers, synthetic polymers, β-CD, and surfactants for CUR loading/encapsulation and controlled release. Furthermore, numerous CUR drug delivery systems, challenges, and techniques for effective loading/encapsulation of CUR on CNCs-based composites have been presented. Finally, conclusions and future outlooks are also explored.

Natural Fiber-Reinforced Thermoplastic ENR/PVC Composites as Potential Membrane Technology in Industrial Wastewater Treatment: A Review

Membrane separation processes are prevalent in industrial wastewater treatment because they are more effective than conventional methods at addressing global water issues. Consequently, the ideal membranes with high mechanical strength, thermal characteristics, flux, permeability, porosity, and solute removal capacity must be prepared to aid in the separation process for wastewater treatment. Rubber-based membranes have shown the potential for high mechanical properties in water separation processes to date. In addition, the excellent sustainable practice of natural fibers has attracted great attention from industrial players and researchers for the exploitation of polymer composite membranes to improve the balance between the environment and social and economic concerns. The incorporation of natural fiber in thermoplastic elastomer (TPE) as filler and pore former agent enhances the mechanical properties, and high separation efficiency characteristics of membrane composites are discussed. Furthermore, recent advancements in the fabrication technique of porous membranes affected the membrane's structure, and the performance of wastewater treatment applications is reviewed.