Functionalized Cellulose Nanocrystals Research Articles

Sustainable preparation of surface functionalized cellulose nanocrystals and their application for Pickering emulsions

Herein, a highly efficient and sustainable approach, namely HCl-catalyzed para-toluene sulfonic acid/Formic acid (p-TsOH/FA) hydrolysis was reported to produce surface functionalized cellulose nanocrystals (CNCs). The optimized CNCs showed a high yield (79.6 %), high crystallinity (70.6 %) and high thermal stability (maximal weight loss temperature around 350 °C). In addition, the as-prepared CNCs possess excellent ability to stabilize oil-water due to the introduction of functional formyl groups, which could be promising stabilizers for Pickering emulsions (PEs). At a fixed oil-water ratio (2:8, v:v), the CNCs with the concentration of 0.5 wt% to 2.0 wt% could stabilize peanut oil to make PEs, and the emulsion droplets were <5 μm in diameter. In addition, the stability of the PEs at different temperature, pH, ionic strength, and long storage time were studied. The results indicated that the obtained CNCs could be sustainable and superior stabilizers for PEs.

Synthesis of urea-containing sodium alginate-g-poly(acrylic acid-co-acrylamide) superabsorbent-fertilizer hydrogel reinforced with carboxylated cellulose nanocrystals for efficient water and nitrogen utilization

A novel slow-release nitrogen fertilizer hydrogel nanocomposite was fabricated by in-situ free radical copolymerization between sodium alginate (SA), acrylic acid (AA), and acrylamide (AM) in an aqueous media using N, N’methylene bis-acrylamide (MBA) as a crosslinker, citric acid-functionalized cellulose nanocrystals (C-CNC) as a nanofiller and urea as a source of nitrogen. Several variables influencing the water absorbency of the fabricated hydrogels were studied and optimized. The optimized Hyd/C-CNC and Hyd/C-CNC/urea were fully characterized to determine their structure, thermal stability, and morphology. Swelling behavior in saline solutions such as (NaCl, CaCl2, and FeCl3) and at various pHs (2−12) as well as the swelling kinetics were investigated. The incorporation of functionalized cellulose nanocrystals into the hydrogel was very beneficial since it boosts the water absorbency from 260 ± 8 g/g for hydrogel without C-CNC to 316 ± 10 g/g for the hydrogel with 1.5 wt% of C-CNC. The soil experiment showed an enhanced soil water-retention capacity after the addition of 1 wt% of the Hyd/C-CNC polymer. The addition of urea confers to the Hyd/C-CNC material an enhanced water retention property and a slow-release nitrogen property. Under optimized conditions, the Hyd/C-CNC/urea had a total nitrogen amount of 13.66%, a high swelling degree (412 ± 4 g/g), and prolonged nitrogen release duration (20 days for complete N-release). Thus, the good water adsorption capacity, as well as the good slow-release fertilizer property, make this material a suitable water-saving material for agriculture applications.

Highly efficient removal of arsenic (III/V) from groundwater using nZVI functionalized cellulose nanocrystals fabricated via a bioinspired strategy

Utilizing nanoscale zero valent iron (nZVI) to purify groundwater contaminated by arsenic species [As(III/V)] is an efficient technology, but the fast and severe aggregation of nZVI limits its practical applications. Herein, nZVI was anchored onto the mussel-inspired polydopamine-coated cellulose nanocrystals (CNCs-PDA-nZVI) as an efficient material for As groundwater remediation. In this set, the introduction of nZVI was expected to significantly enhance the arsenic removal property, while cellulose nanocrystals (CNCs) endowed nZVI with ultrahigh dispersibility. The batch results showed that the maximum As adsorption capacities of CNCs-PDA-nZVI (i.e., 333.3 mg g−1 and 250.0 mg g−1 for As(III) and As(V), respectively) were ten times higher compared with those of pristine CNCs. The kinetics results revealed that chemical adsorption was dominant for As adsorption. The isotherms indicated that a homogeneous adsorption for As(III) and heterogenous adsorption for As(V) on the surface of CNCs-PDA-nZVI. The removal mechanisms for As by CNCs-PDA-nZVI included adsorption-oxidation, coprecipitation and inner-sphere complexation. Overall, the excellent arsenic removal efficiency makes CNCs-PDA-nZVI a promising material for the remediation of As polluted groundwater, and this in-situ anchoring strategy can be extended to overcome the aggregation bottleneck of other nanoparticles for various applications.

Experiment and molecular dynamics simulation of functionalized cellulose nanocrystals as reinforcement in cement composites

This study evaluated the potential effect of cellulose nanocrystal and coated polyethylene fiber on the mechanical properties of mortar. Two kinds of cellulose nanocrystals (CNC) directly as Nano-materials, and indirectly as film coated onto the polypropylene fibers were employed as cement-based reinforcement materials. The fluidity, flexural and compressive strength, and the microstructure of each specimen were measured. In the direct method, mortar mixed with the CNC containing carboxyl groups (CNC-C) showed superior properties compared to the CNC containing sulfo groups (CNC-S). The addition of CNC impacted the process of hydration and compactness of hydration products. The results of X-Ray polycrystalline diffractometer (XRD) and heat of hydration showed that CNC accelerated hydration process. Energy spectrum analysis (EDS) measured ratio of calcium to silicon (C/S) of calcium silicate hydrate (C-S-H) and proved that CNC-C increased the tightness of C-S-H while CNC-S decreased. The results of scanning electron microscopy (SEM) indicated that cellulose nanocrystals were interspersed in C-S-H, forming Nano-bridge and arresting Nano-crack. In the indirect method, the maximum increase in flexural strength of sample between all groups was the specimen that adding 0.3% (volume ratio of fiber to mortar) of CNC-C coated polypropylene fibers. The flexural and compressive strength of the mortar were increased by 22.81% and 10.65% compared to the control, respectively. The results of SEM indicated that coating enhanced bond of the fibers/matrix. Molecular dynamics simulation (MD) analyzed the binding energy, microstructure, dynamic characteristics and adsorption conformation between two CNCs and C-S-H at the molecular scale. MD presented clearly that the adsorption energy between CNC-S and C-S-H was much smaller than CNC-C and C-S-H. This was identical with CNC-C enhancing the mechanical properties of the mortar and CNC-S reducing the mechanical properties.

Size exclusion and affinity-based removal of nanoparticles with electrospun cellulose acetate membranes infused with functionalized cellulose nanocrystals

Membrane filtration and affinity-based adsorption are the two most used strategies in separation technologies. Here, µm-thick multifunctional and sustainable composite membranes of electrospun cellulose acetate (CA) infused with functionalized, anionic, and cationic cellulose nanocrystals (CNCs) with enhanced wettability, tensile strength, and excellent retention capacities were designed. CNCs could uniformly impregnate into the three-dimensional CA network to effectively improve its properties. The impregnation of cationic CNCs at 0.5 wt% concentration drastically increased the tensile strength (1669%) while maintaining high permeation flux of 9400 Lm-2h−1 which is remarkable with cellulose modified electrospun membranes. The membranes infused with anionic CNCs exhibited a particle retention efficiency of 96% for 500 nm and 77% for 100 nm latex beads whilst the cationic CNC membranes exhibited a combined particle retention strategy using selectivity and size exclusion with a retention of >81% with 100 nm latex beads and 80% with ∼50 nm silver nanoparticles. We envision that the developed multifunctional membranes can be utilized for affinity-based and size-exclusion filtration to selectively trap bacteria or substances of biological significance.

The Preparation and Properties of Composite Hydrogels Based on Gelatin and (3-Aminopropyl) Trimethoxysilane Grafted Cellulose Nanocrystals Covalently Linked with Microbial Transglutaminase.

Mechanically enhanced gelatin-based composite hydrogels were developed in the presence of functionalized cellulose nanocrystals (CNCs) employing microbial transglutaminase (mTG) as a binding agent. In this work, the surfaces of CNCs were grafted with (3-Aminopropyl) trimethoxysilane with a NH2 functional group, and the success of CNCs’ modification was verified by FTIR spectroscopy and XPS. The higher degree of modification in CNCs resulted in more covalent cross-linking and dispersibility within the gelatin matrix; thus, the as-prepared hydrogels showed significantly improved mechanical properties and thermo-stability, as revealed by dynamic rheological analysis, uniaxial compression tests and SEM. The biocompatibility of the obtained hydrogels was evaluated by the MTT method, and it was found that the grafted CNCs had no obvious inhibitory effect on cell proliferation. Hence, the mechanically enhanced gelatin-based hydrogels might have great potential in biomedical applications.

Fabrication of modified nanofiltration membranes by functionalized cellulose nanocrystals with high anti-fouling capability in removing dye from water and wastewater

Fabrication of modified nanofiltration membranes by functionalized cellulose nanocrystals with high anti-fouling capability in removing dye from water and wastewater

Size Exclusion and Affinity-Based Removal of Nanoparticles with Electrospun Cellulose Acetate Membranes Infused with Functionalized Cellulose Nanocrystals

Size Exclusion and Affinity-Based Removal of Nanoparticles with Electrospun Cellulose Acetate Membranes Infused with Functionalized Cellulose Nanocrystals

Nanocomposite Hydrogels Flexible Sensors with Functional Cellulose Nanocrystals for Monitoring Human Motion and Lactate in Sweat

Nanocomposite Hydrogels Flexible Sensors with Functional Cellulose Nanocrystals for Monitoring Human Motion and Lactate in Sweat

Temperature-Invariant Superelastic Multifunctional MXene Aerogels for High-Performance Photoresponsive Supercapacitors and Wearable Strain Sensors.

Assembling MXene two-dimensional (2D) nanosheets solely into structurally robust three-dimensional (3D) multifunctional macroarchitectures with temperature-invariant elasticity is significant for widening their potential applications but has remained exceedingly challenging. To this end, a facile freeze-induced co-assembly was developed to allow the disparate integration of MXene 2D nanosheets into the directive heterogeneities to easily customize the controllable 3D architectures for geometry accessibility, structure integrity, and function adaptability. With functionalized cellulose nanocrystal serving as a structural modifier and cross-linking by polyurethane as well as manipulating the directionally ice templating process, multilevel nanostructured configurations with interconnected porous channels could be obtained for biomimetic aerogel electrodes across multiple length scales. Benefiting from the high ion pathway from the low-tortuosity topology, MXene aerogels showed outstanding electrochemical property (225 F/g), high-rate capacity, and temperature-invariant superelasticity (from 0 to 150 °C), which surpassed some of the best reported values. MXene quasi-solid-state supercapacitors presented superior electrochemistry (energy density: 38.5 μWh/cm2) and outstanding cycle ability (86.7% after 4000 cycles). Exhibiting excellent photoresponse capacity, they could be used as an integrated photodetector. More importantly, specially designed bio-mimicking structures with mechanically self-adaptive resilience could promote MXene 3D aerogels to apply in wearable electronic devices, monitoring various human motions. This work will shed light on MXene aerogels for smart and self-powered lightweight electronics.

Cellulose nanocrystals from agricultural resources: Extraction and functionalisation

During the early nineteens, enhanced concern towards “biodegradable materials” and “green chemistry,” along with the significant advancements in nanotechnology, coerce scientists and scholars to ferret out an alternative biomaterial. Prolonged rummage to the alternate biomaterial leads to the discovery of nanoparticles from cellulose as cellulose nanocrystal composites. Various cellulosic sources yield nano cellulosic derivatives after various pretreatment and extraction procedures, including acid hydrolysis, micro grinding, cryocrushing, electron spinning, and centrifugal spinning. Agricultural resources like cotton, wheat, garlic, ramie, switchgrass, and curaua for cellulose nanocrystal composites extraction of varying properties; hence are applicable for distinct functions. Extraction from agricultural resources adds more profit and advancement in the agricultural sector. Pure cellulose nanocrystal composite possesses a mechanical strength of 7000 MPa, a young modulus of 100–140 GPa, and 250–500 m 2 /g surface area. The vulnerability of cellulose nanocrystal composites towards moisture due to alcoholic group nullifies by the modification and grafting processes which yield functionalized cellulose nanocrystal composites. Functionalized cellulose nanocrystal composites find applications in various fields, including biomedicine, catalysis, electronics, and laboratories. The review summarises the extraction procedure of cellulose nanocrystal composites from agricultural resources and functionalization methodologies, facilitating cellulose nanocrystal composite's prospective implementation.

Chitosan functionalized cellulose nanocrystals for stabilizing Pickering emulsion: Fabrication, characterization and stability evaluation

In this study, cellulose nanocrystals (CNC)/chitosan (CS)/glutaraldehyde (Glu) ternary composites were synthesized using cross-linking method with different CNC/CS ratios (1:1, 2:1, 3:1, 4:1, w/w). The composites were firstly characterized using various techniques, such as SEM, FT-IR, isothermal nitrogen adsorption/desorption and TGA. They were further used as solid stabilizers for the preparation of O/W Pickering emulsions. The appearance of emulsions, size and zeta potential and rheological properties of the droplets were investigated. The results showed that the cross-linked biopolymer composites had high surface area, variable morphology and special three-dimensional networks, and showed good emulsifying capacity. Furthermore, the droplet size and zeta potential of emulsions as functions of pH (2–12), temperature (4–60 °C) and ion strength (0–1000 mM) were studied, and the results confirmed that the emulsions prepared with CNC/CS composites had good physical stability at different varying conditions. This study suggested that CNC/CS composites could significantly improve the emulsifying capacity and therefore had great potential for application in the pharmaceutical and food sciences.

Fabrication of high transparent, mechanical strong, and flame retardant waterborne polyurethane composites by incorporating phosphorus‐silicon functionalized cellulose nanocrystals

AbstractTo manufacture transparent waterborne polyurethane composite coatings that possess desirable mechanical and flame retardancy properties is still a challenge. Herein, we first synthesized phosphorus‐silicon functionalized cellulose nanocrystals (FCNC) filler, and further introduced it into waterborne polyurethane (WPU) matrix to prepare composite. The phosphorus‐silicon‐containing components were grafted covalently on the surface of FCNC, and the FCNC showed good dispersion level in water and WPU matrix. Moreover, the inserted FCNC could not only maintain the high transparency of WPU‐FCNCs composites, but also remarkably enhancing the mechanical and flame retardancy performances. Noticeably, the WPU‐FCNC3 composite containing 3 wt% of FCNC showed balanced mechanical (σb = 16.7 MPa, εb = 557.5%), limiting oxygen index (22.9%), and a UL‐94 rating of V‐2 among prepared films. Additionally, WPU‐FCNC3 composite exhibited significantly reductions in heat release during combustion, and also showed a high transmittance of 92.2%. The present research supplies promising way for developing transparent, toughness, and flame retardant composite coatings.

Chemically Functionalized Cellulose Nanocrystals as Reactive Filler in Bio-Based Polyurethane Foams.

Cellulose Nanocrystals, CNC, opportunely functionalized are proposed as reactive fillers in bio-based flexible polyurethane foams to improve, mainly, their mechanical properties. To overcome the cellulose hydrophilicity, CNC was functionalized on its surface by linking covalently a suitable bio-based polyol to obtain a grafted-CNC. The polyols grafted with CNC will react with the isocyanate in the preparation of the polyurethane foams. An attractive way to introduce functionalities on cellulose surfaces in aqueous media is silane chemistry by using functional trialkoxy silanes, X-Si (OR)3. Here, we report the synthesis of CNC-grafted-biopolyol to be used as a successful reactive filler in bio-based polyurethane foams, PUFs. The alkyl silanes were used as efficient coupling agents for the grafting of CNC and bio-polyols. Four strategies to obtain CNC-grafted-polyol were fine-tuned to use CNC as an active filler in PUFs. The effective grafting of the bio polyol on CNC was evaluated by FTIR analysis, and the amount of grafted polyol by thermogravimetric analysis. Finally, the morphological, thermal and mechanical properties and hydrophobicity of filled PUFs were thoughtfully assessed as well as the structure of the foams and, in particular, of the edges and walls of the cell foams by means of the Gibson–Ashby model. Improved thermal stability and mechanical properties of PU foams containing CNC-functionalized-polyol are observed. The morphology of the PU foams is also influenced by the functionalization of the CNC.

One-pot green extraction of high charge density cellulose nanocrystals with high yield for bionanocomposites

The use of lignocellulosic materials for extracting functionalized cellulose nanocrystals (FCNs) in a green and sustainable method under mild conditions is limited owing to the strong hydrogen bonding in cellulose. A facile, green, and high-efficient avenue was developed to produce FCNs with high yield through the mechanochemistry synergetic effect of recyclable p-toluenesulfonic acid (PTSA)-catalyzed deep eutectic solvent (PDES) and microwave- solvothermal (MWS). FCNs with a high charge density of 1.59 e nm−2, a crystallinity of 81%, a better thermostability and dispersibility were obtained at a high yield of 87.6% by the one-step processing. The PDES could be easily recycled, and thus was beneficial to cost reduction and waste liquor treatment. Generated FCNs could be used to develop functional bionanocomposites due to their enhanced effect. When a loading of 1 wt% FCNs was added into gelatin matrix, the tensile strength and Young’s modulus of the bionanocomposites increased 188 and 131%, respectively, suggesting their remarkable stress transfer potential. Thus, the study demonstrates a green and cost-effective approach for the mass production of FCNs, contributing to strong potential in building high-performance bionanocomposites.

Selective adsorption and separation of organic dyes using functionalized cellulose nanocrystals

• Functionalized cellulose nanocrystals (CNCs) for dye absorption. • Selective binding of methylene blue by polydopamine-CNC. • ITC analysis confirmed the types of binding interactions. In this study, cellulose nanocrystals (CNCs) were evaluated as potential adsorbents for the selective adsorption and separation of organic dyes mixtures (methylene blue (MB), with either methyl orange (MO) or rhodamine b (RB) or crystal violet (CV)). The role of surface functional groups on the dye-CNC interaction was examined using pristine and surface-functionalized CNCs, such polydopamine (PD) and melamine–formaldehyde (MF) coated CNCs (PD-CNCs and MF-CNCs respectively). Batch adsorption studies on MB/MO dye mixture showed that pristine CNCs bearing anionic sulfate ester groups exhibited preferential adsorption for MB, with a 85.78% adsorption efficiency. This preferential adsorption was further enhanced in the case of PD-CNCs, which showed 100% adsorption efficiency for MB. Additional studies on MB/RB and MB/CV dye mixtures confirmed that the improved selectivity of PD-CNCs towards MB is associated with the synergistic binding interactions, such as electrostatic attraction, π-π stacking, and hydrogen bonding. MF-CNCs with cationic amine groups displayed selective binding towards MO, an anionic dye. Also, PD-CNCs and MF-CNCs were found to completely separate MB and MO from a diluted MB/MO dye mixture. Isothermal titration calorimetry and dye flocculation experiments confirmed that the selective binding is associated with the surface-functionality of CNCs.

Pillar[6]arene-modified gold nanoparticles grafted on cellulose nanocrystals for the electrochemical detection of bisphenol A

The as-prepared CNCs@CP6-AuNP nanohybrid and its application in sensing BPA.

Functionalized Cellulose Nanocrystals for Cellular Labeling and Bioimaging.

Cellulose nanocrystals (CNCs) are unique and promising natural nanomaterials that can be extracted from native cellulose fibers by acid hydrolysis. In this study, we developed chemically modified CNC derivatives by covalent tethering of PEGylated biotin and perylenediimide (PDI)-based near-infrared organic dye and evaluated their suitability for labeling and imaging of different cell lines including J774A.1 macrophages, NIH-3T3 fibroblasts, HeLa adenocarcinoma cells, and primary murine dendritic cells. PDI-labeled CNCs showed a superior photostability compared to similar commercially available dyes under long periods of constant and high-intensity illumination. All CNC derivatives displayed excellent cytocompatibility toward all cell types and efficiently labeled cells in a dose-dependent manner. Moreover, CNCs were effectively internalized and localized in the cytoplasm around perinuclear areas. Thus, our findings demonstrate the suitability of these new CNC derivatives for labeling, imaging, and long-time tracking of a variety of cell lines and primary cells.

“Soft-rigid” synergistic reinforcement of PHBV composites with functionalized cellulose nanocrystals and amorphous recycled polycarbonate

Herein, both rigid cellulose nanocrystal with photoactive groups (CNC-Cc) and amorphous polycarbonate (extracted from discarded CD) were functionalized as reinforcing agents to obtain poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/polycarbonate/CNC-Cc (PHBV/PC/CNC-Cc) composite films via a Pickering emulsion approach. With the addition of PC and CNC-Cc, an obvious “soft-rigid” synergistic effect on the performances of PHBV matrix was found. Compared to neat PHBV, the best mechanical strength/toughness of PHBV/PC/CNC-Cc-7 increased by 273.8%/821.9%. Meanwhile the PHBV/PC/CNC-Cc-7 nanocomposite showed excellent UV shielding, antioxidant, and antibacterial abilities, due to dynamic competition effect of amorphous PC and rigid CNC-Cc on the PHBV microstructure and interaction. Therefore, this work could solve the current problems of poor mechanical flexibility of biopolymers for potential applications in easy-oxidized food packaging.

Wood-inspired superelastic MXene aerogels with superior photothermal conversion and durable superhydrophobicity for clean-up of super-viscous crude oil

It remains a great challenge to develop functional aerogels with superior mechanical robustness, durable superhydrophobicity, and excellent photothermal conversion ability for the promising next generation of oil/water separation materials and energy regulation systems. Herein, inspired by wood structures, we proposed a facile strategy to develop MXene aerogels with super-elasticity, self-cleaning, excellent joule heating and superior photothermal conversion ability. Functionalized cellulose nanocrystal was synthesized via green mechanochemistry, which served as a wetting modifier and dispersant. MXene was applied to construct functional networks in waterborne polyurethane. With fine-tuning of nucleation-driving, the desirable microstructures could be controllably diversified for structure-adaptable functionality. The wood-inspired MXene aerogel showed durable superhydrophobicity (CA ≈ 152°), mechanical superelasticity (76.2% strain remaining after 100 compress-release cycles), highly efficient absorption capacity of light oil (63 g/g) and superior photothermal conversion ability. Also, the as-prepared MXene aerogel demonstrated ultrahigh viscosity crude oil (c.a.130000 mPa.s) absorption capacity of 24.5 g/g under 1 sun irradiation and recyclability of 76% after 5 cycles, much higher than those of the reported. This study provides a promising strategy for constructing integrated multifunctional aerogels with superior mechanical robustness to meet the increasing demands in many fields such as energy regulation devices and crude oil absorbents.