Modified Cellulose Nanocrystals Research Articles

Carboxymethyl chitosan and dialdehyde cellulose nanocrystal based injectable self-healing emulsion gel

The study aims to demonstrate a general method for producing emulsion gels with self-healing properties. Specifically, the self-healing emulsion gels were fabricated by crosslinking carboxymethyl chitosan (CMC) stabilized emulsion with dialdehyde cellulose nanocrystal (DACNC). The reversible imine bonds between primary amino groups from CMC and aldehyde groups from DACNC endow the emulsion gel with self-healing properties. The compressive strength of the emulsion gels was greatly increased from 37.43 kPa 83.7 kPa by encapsulating emulsion droplets (φ = 0 %–40 %.) in the gel matrix. Moreover, the emulsion gels exhibited much better self-healing and injectability ability compared to hydrogel because the emulsion droplets interacted with the 3D gel matrix, which were observed by cryo-SEM and CLSM. The emulsion droplets distributed in the gel matrix improved the mobility and interfacial contact area of CMC and DACNC. Water contact measurement confirmed that the CMC/DACNC self-healing emulsion gels showed a hydrophilic surface. The CMC/DACNC emulsion gels could maintain a good structural stability as the oil loss was <1 % after centrifugation. This research provides a method to keep the structural stability of emulsion gels by inducing self-healing ability and modified cellulose nanocrystals, which could extend the shelf life and application area of emulsion gels.

Dielectric, transparent, thermally stable and mechanically robust bionanocomposite films based on chitosan and modified cellulose nanocrystals

AbstractThe growing demand for electronics necessitates the development of novel environmentally responsible materials. A potential approach involves incorporating renewable and sustainable materials with mechanical and electrical properties while ensuring environmentally friendly disposal. Herein, this study reports the dielectric properties of chitosan (CS) reinforced with cellulose nanocrystals (CN) extracted from post‐harvest tomato plant residue. The resulting bionanocomposite material demonstrated remarkable characteristics, including dielectricity, transparency, thermal stability, and mechanical robustness. Additionally, the effect of high‐loading fillers (5 and 10 wt %) on the final properties of the material is investigated, as well as the effect of surface functionality of the CNs. The results showed that both the high‐loading fillers and the surface functionality of the CNs had a significant impact on the properties of the nanocomposite material. The bionanocomposite materials produced in this study hold great potential as an eco‐friendly substitute for conventional electronic materials and beyond. Its dielectric, transparent, thermally stable, and mechanically robust properties render it well‐suited for diverse applications.Highlights The phosphorylated groups insured high Crl (%) and high interface between the filler and matrix. High interface and crystallinity enhanced the mechanical characteristics. Low crystallinity increases the dielectric constant, case of 5% CNS. Filler’ type can tailor and optimize the energy dissipation up to tan δ = 0.5 for 5% CNP. Detection of Warburg impedance proves the interface polarization presence.

Self-assembly of modified cellulose nanocrystals on flexible fabric via hydrophobic force induction for versatile applications

Over the years, there has been a proliferation of superhydrophobic fabrics constructed by self-assembly techniques. However, most of these suffer from poor mechanical durability and chemical stability, while the complexity of the process severely limits their practical application in textiles with special functionalities. In this study, We have built a self-assembly coating with many advantages such as large specific surface area, ultra-fast, high particle utilization, and dense and homogeneous alignment of particles. We modified cellulose nanocrystals (m-CNCs) using a variety of hydrophobic monomers, and the modified cellulose nanocrystals were suspended in a solution of isopropanol-containing end-hydroxy polysiloxane (MSDS) and hydrogen-containing polysiloxane (PHMS). The silicone system was used to treat a cotton fabric to obtain a superhydrophobic fabric by hydrophobically inducing modified cellulose nanocrystals to self-assemble on the fibre surface. Unlike many previous studies, owing to the m-CNC particles being chemically bonded between the multilayer nanostructure and the fabric, the coating had excellent mechanical durability and remained superhydrophobic after abrasion by sandpaper or peeling with tape. In addition, the nanostructure of the coating surface trapped air in the surface pores, preventing the penetration of H+, Na+, Cl−, and OH− in liquids; thus, the fabric remained hydrophobic both under extreme solution conditions and after soaping cycle tests, showing excellent stability and cycling ability. At the same time, the breaking strength of the fabric is improved after finishing, and the wearability is almost unchanged. Coated fabrics have good potential in the fields of self-cleaning, anti-staining, oil absorption, and oil–water separation.

Self‐healing waterborne fluorinated polyurethane‐acrylate based on photoreversible reaction and hydrogen bonds

AbstractThe development of self‐healing materials is an effective strategy to improve the service life of polymer materials. In this study, self‐healing waterborne fluorinated polyurethane‐acrylate (WFPUA) containing UV‐responsive coumarin groups was prepared by Pickering emulsion polymerization using modified cellulose nanocrystal as a stabilizer. The effect of double bond‐terminated waterborne polyurethane content on emulsion polymerization and latex film properties was mainly studied. Due to the dynamic reversibility of the coumarin groups and the synergistic effect of hydrogen bonds, the optimized sample (WFPUA‐30) had excellent mechanical properties and self‐healing properties. The tensile strength was 5.24 MPa and the elongation at break was 267%. The self‐healing efficiency of tensile strength and elongation at break after 6 h of repair was 86.52% and 93.20%, respectively. In addition, due to the presence of fluorine‐containing groups, the water and oil contact angles of the latex film could reach 101.7° and 82.1°, respectively. This work broadens the way for the manufacture of self‐healing and multifunctional waterborne polyurethane‐acrylates. © 2024 Society of Industrial Chemistry.

Poly-(lactic acid) composite films comprising carvacrol and cellulose nanocrystal–zinc oxide with synergistic antibacterial effects

Herein, carvacrol (CRV) and modified cellulose nanocrystal–zinc oxide (CNC–ZnO) were incorporated into a poly (lactic acid) (PLA) matrix to prepare a PLA-based composite film using a simple solution casting method to achieve antimicrobial effects for application in antimicrobial food packaging. Compared with films obtained from neat PLA, the PLA@CRV20%@CNC–ZnO3% composite film shows better performance in terms of mechanical properties, ultraviolet (UV) blocking, and antimicrobial effects. The PLA composites containing CRV and 3 wt% CNC–ZnO blends exhibit improved tensile strength (21.8 MPa) and elongation at break (403.1 %) as well as excellent UV resistance. In particular, CRV and the CNC–ZnO hybrid endow the obtained PLA composite films with a synergistic antibacterial effect, resulting in good antibacterial properties for microbes, such as Escherichia coli, Staphylococcus aureus and Aspergillus niger. The diameters of the inhibition zone of the PLA@CRV20%@CNC–ZnO3% composite films against E. coli, S. aureus, and A. niger were 4.9, 5.0, and 3.4 cm, respectively. Appling the PLA@CRV20%@CNC–ZnO3% composite film as an antibacterial food packaging material, the storage period for strawberries was considerably extended. This study provides a theoretical basis for developing new organic/inorganic composite antimicrobial film materials from PLA.

Cellulose nanocrystals/fluorinated polyacrylate with mechanical tunability, water-oil resistance and self-healing capability via light actuated reversible associations

Traditional fluorinated polyacrylate has been extensively applied in various fields, which is favored by many researchers. However, the polymer usually can lose usefulness when it is damaged. Endowing the polymer with self-healing capability provides a potential solution to address the conflict. Herein, a series of photo actuated self-healing fluorinated polyacrylate based on coumarin groups was synthesized by reversible addition-fragmentation chain transfer (RAFT)-assisted Pickering emulsion polymerization using the modified cellulose nanocrystals as the stabilizer, n-butyl acrylate (BA) as the soft monomer, and methyl methacrylate (MMA) as the hard monomer. The influences of the dosage of 7-(4-vinylbenzyloxy)−4-methylcoumarin) (VBMC) and the mass ratio of BA to MMA on the emulsion polymerization and latex film properties were studied. The results showed that the latex particle size and its distribution decreased and then increased as the VBMC dosage and the mass ratio of BA to MMA increased. The latex film exhibited not only high ultimate tensile stress (6.36 MPa) and large stretchability (575.71%) but also a certain anti-fatigue characteristic. The water and oil contact angles of latex film could reach 118.5° and 101.7°, respectively. Besides, the latex film could achieve efficient self-healing capability due to the mobility of polymer chains associated with low glass transition temperature (Tg) and the reversible [2+2] cleavage/dimerization reaction of the coumarin groups upon ultraviolet (UV) irradiation of 254 nm and 365 nm. The work offers a substantial reference for developing different light actuated self-healing polymers with great prospects and promising futures.

Modified cellulose nanocrystals enhanced polycaprolactone multifunctional films with barrier, UV-blocking and antimicrobial properties for food packaging

The packaging industry demands improved eco-friendly materials with new and enhanced properties. In this context, bio-nanocomposite films with antimicrobial and UV-shielding properties based on modified cellulose nanocrystals/polycaprolactone (MCNC/PCL) were fabricated via solution casting method, and then food packaging simulation was carried out. CNCs were obtained by acid hydrolysis followed by successful functionalization with Quaternary ammonium surfactant, confirmed by FTIR, XPS, XRD, TEM, and DLS analyses. Furthermore, the morphological, physical, antibacterial, and food packaging properties of all prepared films were investigated. Results showed that the mechanical, UV blocking, barrier properties, and antibacterial activity of all composite films were remarkably improved. Particularly, the addition of 3 wt% MCNC increased the tensile strength and elongation at break by 27.5 % and 20.0 %, respectively. Moreover, the permeability of O2, CO2, and water vapor dramatically reduced by 97.6 %, 96.7 %, and 49.8% compared to the Neat PCL. Further, the UV-blocking properties of the composite films were significantly improved. The antimicrobial properties of MCNC/PCL films showed good antimicrobial properties against S. aureus. Finally, cherry packaged with 1 and 3 wt% MCNC films exhibited satisfactory freshness after 22 days of preservation. Overall, the fabricated PCL nanocomposite films can be utilized in the food packaging industry.

Low-concentration octadecylamine based nano cellulose prepared by acid hydrolysis method improving the toughness and thermal stability of epoxy resin

Modified cellulose nanocrystals were prepared by hydrolyzing softwood pulp board with acrylic acid and p-toluenesulfonic acid, and then the nano cellulose was modified by introducing Octadecylamine into the nano cellulose. Then the modified nano cellulose was dispersed in epoxy resin (EP) to obtain Octadecylamine (ODA) modified nano cellulose-based epoxy resin composites (ONCA/EP) with high strength and good toughness. Moreover, the problem of poor dispersion of nano cellulose in EP is improved. FTIR and X-ray diffraction (XRD) confirmed the modified nano cellulose.The application properties were determined through particle size analysis, thermogravimetric analysis (TGA-DSC), mechanical property analysis, TEM and SEM. ONCA/EP nano composites have excellent mechanical properties and thermal stability due to inadequate concentration of modified nano cellulose doping. The results show that by introducing 2 % ONCA only, the strength reached the highest 74.03 MPa, and the elongation at break reached 3.64 %; the residual mass at 800℃ increased by 3.68 % compared to pure EP. The research utilizes biodegradable nano cellulose for EP modification, opening up new avenues for the applying of nano cellulose in the field of materials science. It is of great significance in enhancing epoxy resin's performance, promoting sustainable materials' development, and expanding the application areas of nano cellulose.

Biological Potential and Bioaccessibility of Encapsulated Curcumin into Cetyltrimethylammonium Bromide Modified Cellulose Nanocrystals.

Curcumin is a natural phenolic compound with important biological functions. Despite its demonstrated efficacy in vitro, curcumin biological activities in vivo are dependent on its bioaccessibility and bioavailability, which have been highlighted as a crucial challenge. Cetyltrimethylammonium bromide-modified cellulose nanocrystals (CNC-CTAB) have been shown to be effective in curcumin encapsulation, as they have the potential to enhance biological outcomes. This study evaluated the biological effects of curcumin encapsulated within CNC-CTAB structures, namely its antioxidant, anti-inflammatory and antimicrobial properties, as well as the release profile under digestion conditions and intestinal permeability. Encapsulated curcumin demonstrated antioxidant and anti-inflammatory properties, effectively reducing reactive oxygen species and cytokine production by intestinal cells. The delivery system exhibited antimicrobial properties against Campylobacter jejuni bacteria, further suggesting its potential in mitigating intestinal inflammation. The system showed the ability to protect curcumin from degradation and facilitate its interaction with the intestinal epithelium, highlighting the potential of CNC-CTAB as carrier to enhance curcumin intestinal biological functions.

Low-temperature, ultra-fast, and recyclable self-healing nanocomposites reinforced with non-solvent silylated modified cellulose nanocrystals

Developing polymeric materials with remarkable mechanical properties and fast self-healing performance even at low temperatures is challenging. Herein, the polymeric nanocomposites containing silane-treated cellulose nanocrystals (SCNC) with ultrafast self-healing and exceptional mechanical characteristics were developed even at low temperatures. First, CNC is modified with a cyclic silane coupling agent using an eco-friendly chemical vapor deposition method. The nanocomposite was then fabricated by blending SCNC with matrix prepolymer, prepared from monomers that possess lower critical solution temperature, followed by the inclusion of dibutyltin dilaurate and hexamethylene diisocyanate. The self-healing capability of the novel SCNC/polymer nanocomposites was enhanced remarkably by increasing the content of SCNC (0–3 wt%) and reaching (≥99 %) at temperatures (5 & 25 °C) within <20 min. Moreover, SCNC-3 showed a toughness of (2498 MJ/m3) and SCNC-5 displayed a robust tensile strength of (22.94 ± 0.4 MPa) whereas SCNC-0 exhibited a lower tensile strength (7.4 ± 03 MPa) and toughness of (958 MJ/m3). Additionally, the nanocomposites retain their original mechanical properties after healing at temperatures (5 & 25 °C) owing to the formation of hydrogen bonds via incorporation of the SCNC. These novel SCNC-based self-healable nanocomposites with tunable mechanical properties offer novel insight into preparing damage and temperature-responsive flexible and wearable devices.

Effect of Modified Cellulose Nanocrystals on the Structure of Calcium Silicate Hydrate Studied by Molecular Dynamics Simulation and Experiment

Effect of Modified Cellulose Nanocrystals on the Structure of Calcium Silicate Hydrate Studied by Molecular Dynamics Simulation and Experiment

A Review of Modified Cellulose Nanocrystals and their Applications

Abstract: Cellulose is one of the most abundant natural polymers developed in the ecosystem and has been used in many applications for industrial products since ancient times. Although the main sources of cellulose are wood plant, fibers and, additional sources can also be discovered, such as algae, fungi, bacteria, and even some marine organisms (such as tunicates). Mechanical or chemical processes are used to transform cellulosic materials into cellulose nanocrystals due to their efficacy, high aspect ratio, low density, renewability, and non-toxicity. They have drawn a lot of attention in a variety of industries. Here, we discuss various applications and properties in particular mechanical, rheological, liquid crystalline nature, and adhesives to introduce cellulose nanocrystals hydrophilic, colloidal stable, and rigid rod-shaped bio-based nanomaterial with high strength and high surface area. Under various circumstances, it improves the characteristics of various compounds. The grafting of polymers on the surface of cellulose nanocrystals has attracted significant interest in both academia and industry due to the rapidly expanding number of potential applications of surface-modified cellulose nanocrystals, which range from building blocks in nanocomposites and responsive nanomaterials to antimicrobial agents. Furthermore, we explore the most popular polymerization methods, such as surface-initiated ring-opening polymerization, surface-initiated free radical polymerization, surface-initiated atom transferred radical polymerization and surface-initiated controlled radical polymerization that are employed to graft polymers from the surface and reducing end groups of cellulose nanocrystals. In this review, we examine the available literature and provide a summary of recent applications of cellulose nanocrystals, including biomedical application, drug delivery, biosensor, tissue engineering, antibacterial activity, wound healings, etc.

Antibacterial polylactic acid fabricated via Pickering emulsion approach with polyethyleneimine and polydopamine modified cellulose nanocrystals as emulsion stabilizers

Antibacterial biodegradable plastics are highly demanded for food package and disposable medical plastic consumables. Incorporating antibacterial nanoagents into polymer matrices is an effective method to endow polymers with antibacterial activity. However, synthesis of sustainable antibacterial nanoagents with high antibacterial activity via facile approach and well dispersion of them in polymer matrices are still challenging. In this study, polyethyleneimine (PEI) was grafted on surface of cellulose nanocrystals (CNCs) via the oxidation self-polymerization of dopamine (DA) and the Michael addition/Schiff base reaction between DA and PEI. The resulted PEI and polydopamine modified CNCs (PPCs) showed substantially enhanced antibacterial activity and reduced cytotoxicity for NIH3T3 than PEI due to increased local concentration and anchoring of PEI. The minimum concentration of PPCs to achieve antibacterial rate of 99.99 % against S. aureus and E. coli were about 50 and 20 μg/mL, respectively. PPCs displayed outstanding emulsifying ability, and PPC coated polylactic acid (PLA) microspheres were obtained by drying PPC stabilized PLA Pickering emulsion, leading to a well dispersion of PPCs in PLA. PPC/PLA film prepared by hot-pressing displayed great antibacterial performance and enhanced mechanical properties. Therefore, this study proposed a facile approach to fabricate biocompatible antibacterial nanoagents and plastics.

Efficient removal of fluoride ion by the composite forward osmosis membrane with modified cellulose nanocrystal interlayer

In this paper, the performance of three-layer film composite (TFC) forward osmosis (FO) membrane for the retention of fluoride ions was investigated. A cellulose nanocrystal (CNC) interlayer was introduced on the porous substrate by coating method to enhance the hydrophilicity and retention capacity of the FO membrane. In order to improve the dispersibility of CNC, boric acid (BA) and (3-aminopropyl)triethoxysilane (APTES) were used for chemical modification, respectively. The characterization results demonstrated the successful introduction of CNC, BA/CNC and APTES/CNC–CNC interlayers. The introduction of the interlayer enhanced the hydrophilicity of the membrane and increased the negative surface charge, which facilitated the transport of water molecules and the retention of fluoride ions. The FO tests indicated that the water flux of TFC/CNC membrane was increased by 46.4% compared to the original TFC membrane, and the water flux of TFC/APTES-CNC and TFC/BA-CNC membranes were higher than that of TFC/CNC membranes by 5.9% and 13.0%, respectively. 97.0% and 97.6% of the fluoride ions of TFC/BA-CNC and TFC/APTES-CNC could be retained. Based on the molecular simulation of adsorption, it was demonstrated that BA-CNC interlayer was more favorable for the adsorption of water molecules than CNC and APTES-CNC interlayer. This study contributes to the development of high-performance TFC-FO membrane for the treatment of wastewater containing fluoride.

Poly(glycidyl methacrylate) modified cellulose nanocrystals and their PBAT-based nanocomposites

Melt processing of cellulose nanocrystals (CNCs) reinforced nanocomposites is still a serious challenge due to the hydrophilic nature of CNCs and their severe agglomeration tendency within the polymer melt. In this study, chemical modification of CNC through grafting poly(glycidyl methacrylate) (PGMA) with various degrees was implemented. Wettability of the modified CNCs (mCNCs) were controlled and their structure was characterized through Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), optical microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The nanocomposites of polybutylene adipate terephthalate (PBAT) with 3 wt% CNC and mCNC were prepared using an internal melt mixer. To differentiate the effects of CNC and PGMA molecules on the final properties of nanocomposites, PBAT/PGMA compounds were separately prepared. To confirm the chain characterization and molecular weight of the synthesized PGMAs, 1H NMR and gel permeation chromatography (GPC) analysis were conducted. Melt rheological analysis, dynamic mechanical analysis (DMA), DSC, and atomic force microscopy (AFM) were used to monitor the mCNC dispersion quality and the effect of PGMA modification in PBAT compounds. The results revealed that grafting CNC with longer PGMA considerably improved the CNCs' dispersion quality within PBAT. Such dispersion enhancement of long-chain mCNCs and interfacial interaction of PGMA and PBAT resulted in a noticeable increase in storage modulus and complex viscosity of the final nanocomposites.

Surface Functionalization of Sugarcane-Bagasse-Derived Cellulose Nanocrystal for Pickering Emulsion Gel: Microstructural Properties and Stability Efficiency.

An environmentally friendly Pickering stabilizer was developed by upcycling sugarcane bagasse (SCB) into a cellulose nanocrystal (CNC), which was subjected to surface modification by using quaternary ammonium compound to enhance its amphiphilic characteristics. The changes in microstructural properties of modified cellulose nanocrystal (m-CNC), such as surface functional group, thermal stability, surface morphology, elemental composition, and particle size distribution were investigated. Results indicated the success of quaternary ammonium compound grafting with the presence of a trimethyl-alkyl chain on the cellulose structure, while the m-CNC preserves the needle-like nanoparticles in length of ~534 nm and width of ~20 nm. The colloidal profile of m-CNC-stabilized oil-water emulsion gels with different concentrations of m-CNC (1-5 wt%), and oil:water (O:W) ratios (3:7, 5:5, 7:3) were examined. The emulsion gel stability study indicated that the optimal concentration of m-CNC (3 wt%) was able to stabilize all the emulsion gels at different O:W ratios with an emulsion index of >80% for 3 months. It is the minimum concentration of m-CNC to form a robust colloidal network around the small oil droplets, leading to the formation of stable emulsion gels. The emulsion gel with O:W ratio (3:7) with 3 wt% of m-CNC rendered the best m-CNC-oil-droplets dispersion. The m-CNC effectively retained the size of oil droplets (<10 μm for 3 months storage) against coalescence and creaming by creating a steric barrier between the two immiscible phases. Furthermore, the emulsion gel exhibited the highest viscosity and storage modulus which was able to prevent creaming or sedimentation of the emulsion gels.

Polydopamine modified cellulose nanocrystals (CNC) for efficient cellulase immobilization towards advanced bamboo fiber flexibility and tissue softness

Herein, a green facile approach to improve the flexibility of unbleached bamboo kraft pulp (UBKP) via an immobilized enzyme technology is proposed. Polydopamine (PDA) acts as versatile modification and coating materials of cellulose nanocrystals (CNC) for assembling versatile bio-carriers (PDA@CNC). Cellulase biomacromolecules are efficiently immobilized on PDA@CNC to form cellulase@PDA@CNC nanocomposites. The relative enzyme activity, temperature/pH tolerance, and storage stability of cellulase were significantly improved after immobilization. The degree of polymerization treated UBKP decreased by 5.42 % (25 U/g pulp) compared to the control sample. The flexibility of treated fibers was 6.61 × 1014/(N·m2), which was 96.93 % higher (25 U/g) compared to the control and 3.88 times higher than that of the blank fibers. Cellulase@PDA@CNC performs excellent accessibility to fiber structure and induces high degree of fibrillation and hydrolysis of UBKP fibers, which contributes high softness of obtained tissue handsheets. The bio-carrier PDA@CNC within paper framework may further enhance tissue tensile strength. This study proposes a practical and environmentally friendly immobilization approach of cellulase@PDA@CNC for improving the hydrolysis efficiency and flexibility of UBKP fibers, which provides the possibility to maintain the strength of tissue paper while improving its softness, thus broadening the high-value application of immobilized enzyme technology in tissue production.

Preparation and characterization of hexadecyl trimethyl ammonium bromide (HDTMA-Br)-modified cellulose nanocrystals (CNCs) derived from South African waste agricultural residue (Corncobs)

To address the challenges associated with waste management in South Africa, agro-waste products such as corncobs can be valorized into value-added materials like cellulose nanocrystals (CNCs), thus paving the way for the circular economy. This study investigated the extraction of CNCs from South African waste corncobs through mixed acid hydrolysis using a mixture of sulfuric acid and oxalic acid dihydrate in a mass ratio of 1:5. For the first time, CNCs obtained from South African waste corncobs were functionalized using hexadecyl trimethyl ammonium bromide (HDTMA-Br) to enhance their usability in a variety of applications. Characterization techniques such as: Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infra-red (FTIR) spectroscopy, X-ray Diffraction (XRD), and Thermogravimetric analysis (TGA), were used to examine the surface morphology, surface functional groups, crystallinity, and thermal degradation of the isolated and the functionalized CNCs, respectively. SEM images revealed that the waste corncobs were successfully pre-treated due to the fibrous structure and individual particles observed. The TEM image of the prepared CNCs showed needle-shaped nanoparticles with an average diameter of 40 ± 1.11 nm, 178.5 ± 2.3 nm long, and 20.8 ± 1.7 nm wide. According to the XRD pattern, a strong peak showed at2Θ = 22.4(degree) was considered for the determination of the crystallinity of raw cellulose and that of the CNCs. About 64.5% and 78.9% crystallinity were obtained from the raw cellulose and the extracted CNCs, respectively, with approximately 55.25% yield. FTIR spectra of the functionalized CNCs showed the attachment of new functional groups, methyl, and methylene groups, onto the fCNCs’ surface. Furthermore, TGA analysis indicated that functionalized CNCs were more thermally stable compared to non-functionalized CNCs. These findings showed successful isolation and modification of CNCs from South African waste corncobs for their prospective use in wide-ranging applications.

Protein modified cellulose nanocrystals on reinforcement and self-driven biodegradation of aliphatic polyester

Due to the highly environment-dependent biodegradation and uncontrolled degradation period, the long-run feasibility and effectiveness of biodegradable polymers are extensively questioned to solve plastics waste accumulation and pollution problems. This work physically incorporated lipase PS from Burkholderia cepacian on cellulose nanocrystals (CNC) and embedded it in polycaprolactone (PCL) to construct stable and controllable interfacial microenvironment between CNC and PCL for the reinforcement and controllable self-driven biodegradation. The physical adsorption of lipase PS on CNC was studied by monitoring the surface charge and particle size. FT-IR spectra confirmed the successful incorporation of lipase PS and CNC. Compared with CNC, protein-modified CNC had a higher maximum thermal decomposition temperature of 345 °C and lower interfacial tension of 11 mN/m with PCL which provided PCL composites with higher nucleation efficiency and tensile elongation of 1086 % at break. In addition, only 0.67 % embedded lipase PS completely hydrolyzed PCL membranes in <140 h. The post-compression molding at 80–100 °C had negligible influence on the lipase activity, which indicated that CNC could protect the lipase from inactivation in polymer extrusion and compression. This work also highlighted protein-modified CNC as a new technology for polymer reinforcement.

Self-assembly of cellulose nanocrystals on flexible fabric via a metal coordination strategy for versatile applications

Cotton fabric is widely found in nature, and its outstanding breathability, flexibility, and rich surface groups have encouraged material scientists to investigate it. Self-assembly on the surface of cotton fabrics is an ingenious strategy for developing value-added textiles with special functionalities. This study reports a facile, low-cost technique for directing modified cellulose nanocrystal (CNC) self-assembly by copper ions on the surface of cotton fabrics. Uniform dense sea urchin-like modified CNC agglomerates were formed on the fibres surface, which greatly increased itsspecific surface area. Due to the involvement of Cu2+ in the chelation process and the high specific surface area of the micro-nano structure, the antibacterial effect of this coated fabric was up to 99.9 %. Meanwhile, its water stability was greatly improved by secondary treatment with perfluorooctylethyltrimethoxysilane, extending the potential applications of the self-assembled coating. The results showed that the water contact angle of the coated fabric reached 160° ± 0.5°, and the construction of the micro-nano surface structure enabled it to absorb 3 and 5 times of its own weight of n-heptane and carbon tetrachloride. In addition, the coated fabric also has excellent mechanical stability and chemical durability, shows self-cleaning, oil-water separation and many other properties. At the same time, the breaking strength and wearability of the fabric have been improved after the nano-organic coating finishing. Combining the advantages of flexible fabrics and organic nanofillers, coated fabric is expected to bring traditional textiles to the fore in areas such as stain protection, safety, and health care.