Cellulose Nanocrystals Content Research Articles

Improving the decorative performance of UV-curable coatings with iridescent cellulose nanocrystal film.

Cellulose nanocrystals (CNC) possess remarkable mechanical properties, a high aspect ratio, a large specific surface area, and a unique nanostructure, making them a popular choice in various fields. In this study, a CNC suspension was prepared through acid hydrolysis, and subsequently, a film exhibiting iridescence and chiral nematic structure was formed on the cured UV-WA surface via evaporation-induced self-assembly. The mean diameter and length of CNC were determined to be 25.1-33.3 nm and 281.3-404.2 nm, respectively, through transmission electron microscope analysis. The experimental results revealed that the color of the film significantly changes with variations in the CNC suspension concentration. Notably, the formation of the iridescent film is dependent on the concentration of CNC, with concentrations between 1.2% and 2.9% being optimal, and the aspect ratio of the CNC nanoparticles being around 11.3. X-ray diffraction analysis confirmed that the CNC nanoparticles possess the same crystal structure as microcrystalline cellulose (cellulose I). Fourier transform infrared spectroscopy revealed that the C[double bond, length as m-dash]C bond present in the liquid UV-curable coating disappeared upon UV irradiation. The performance of the CNC iridescent film, with varying thickness, was evaluated using UV-vis spectroscopy. The thermogravimetric analysis results indicate that the addition of CNC enhances the membrane's thermal stability and heat resistance. The results indicate that as the thickness of the CNC iridescent film increases, the corresponding UV-vis spectra display a redshift. The UV-WA/CNC shows potential in the field of decoration and establishing a straightforward, cost-effective, and efficient method for producing photonic materials with structural colors.

Leveraging peptide-cellulose interactions to tailor the hierarchy and mechanics of peptide-polymer hybrids.

Inspired by spider silk's hierarchical diversity, we leveraged peptide motifs with the capability to tune structural arrangement for controlling the mechanical properties of a conventional polymer framework. The addition of nanofiller with hydrogen bonding sites was used as another pathway towards hierarchical tuning via matrix-filler interactions. Specifically, peptide-polyurea hybrids (PPUs) were combined with cellulose nanocrystals (CNCs) to develop mechanically-tunable nanocomposites via tailored matrix-filler interactions (or peptide-cellulose interactions). In this material platform, we explored the effect of these matrix-filler interactions on the secondary structure, hierarchical ordering, and mechanical properties of the peptide hybrid nanocomposites. Interactions between the peptide matrix and CNCs occur in all of the PPU/CNC nanocomposites, preventing α-helical ordering, but promoting inter-molecular hydrogen bonded β-sheet formation. Depending on peptide and CNC content, the Young's modulus varies from 10 to 150 MPa. Unlike conventional cellulose-reinforced polymer nanocomposites, the mechanical properties of these composite materials are dictated by a balance of CNC reinforcement, peptidic ordering, and microphase-separated morphology. This research highlights that leveraging peptide-cellulose interactions is a strategy to create materials with targeted mechanical properties for a specific application using a limited selection of building blocks.

Mapping 3D Printability of Ionically Cross-Linked Cellulose Nanocrystal Inks: Architecting from Nano- to Macroscale Structures.

Engineering the rheological properties of colloidal inks is one of the main challenges in achieving high-fidelity 3D printing. Herein, we provide a comprehensive study on the rheological behavior of inks based on cellulose nanocrystals (CNCs) in the presence of given salts to enable high-quality 3D printing. The rheological properties of the CNC suspensions are tailored by considering the nature of the electrolyte (i.e., 10 types of salts featuring different ion sizes, charge numbers, and inter- and intra-molecular interactions) at various concentrations (25-100 mM). A high printing fidelity is achieved in a narrow CNC and salt concentration range, significantly depending on the salt type. The structure-property relationship is explored in a "3D-printing" space (2D map), introducing a guideline for researchers active in this field. To further unravel the effect of salt type on morphological properties, CNC aerogels are developed by freeze-drying the printed structures. The results illustrate that enhancing viscoelastic properties render a denser structure featuring smaller pores.

Preparation and properties of cellulose nanocrystals-reinforced Poly (lactic acid) composite filaments for 3D printing applications

In this work, the composite filaments containing different cellulose nanocrystals (CNCs) were successfully fabricated by using a single screw extruder and used to 3D print. The influence of CNCs contents (0, 0.75, 1, and 2 wt%) on the properties of the filaments and 3D printed samples were evaluated. The properties of the filaments and 3D printed samples were characterized by using SEM, FT-IR, XRD, DSC, TGA, and tensile tests. Results revealed that no chemical changes occurred in the presence of CNCs but improved crystallinity was found. The presence of 2 wt% CNCs slightly improved the thermal stability of the neat PLA filament and 3D printed sample. The tensile strength of the neat PLA filament was enhanced by 18.2% by adding up to 1 wt% CNCs but reduced at 2 wt% CNCs content. For the 3D printed samples, the tensile strength of the neat PLA was improved by 11% with the introduction of 0.75 wt% CNCs and decreased for further CNC addition. In addition, compared with the 3D printed samples, the filaments exhibited a higher tensile strength for all CNCs contents. Furthermore, the water absorption of the composite filaments was increased with increasing the CNCs contents. On the other hand, the 3D printed samples containing CNCs showed a lower water absorption than the neat PLA.

CNC Synthesis from Cellulose Macromolecule and Fabrication of PVA/TiO2/CNC Bio-Nanocomposite Thin Film for Biomedical Applications

PolyVinyl Alcohol (PVA) based films with varying concentrations of Cellulose Nano Crystals (CNC) and Titanium dioxide (TiO2) have been prepared and characterised in this study to determine their applications in the biomedical field. Biophysical, microscopic and mechanical property characterization of the films - PVA/CNC/T0.5, PVA/CNC/T1.0 and PVA/CNC/T1.5 were performed. The CNC were extracted from pea peel waste fibres (PPWF) which are rich in cellulose macromolecule (Mol Wt > 5000 da) by adopting acid hydrolysis method. Through Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis, uniform distribution and successful incorporation of CNC and TiO2 in the films have been confirmed. From the X-ray diffraction pattern of the films, it could be noted that the crystallinity increased in the films with the addition of CNC and rutile TiO2 in the PVA. The tensile strength of the films also greatly improved with the CNC reinforcement and increase in TiO2 content in the films. Overall, the results of this study suggest that the PVA/CNC/ TiO2 films have the potential to find their application in biomedical devices, especially to be used as a footprint of an ultrasound transducer.

Green-in-green biohybrids as transient biotriboelectric nanogenerators

Green self-powered devices based on biodegradable materials have attracted widespread attention. Here, we propose the construction of the transient biotriboelectric nanogenerator (TENG) using green-in-green bionanocompoites. The green-in-green nanocomposites, cellulose nanocrystal (CNC)/polyhydroxybutyrate (PHB), are prepared with a high-pressure molding method. The CNC promotes the degradation and enhances the dielectric constant of CNC/PHB. It further allows for the significant improvement of the triboelectric output of CNC/PHB-based TENG. The voltage output and current output of CNC/PHB-based TENG are 5.7 and 12.5 times higher than those of pristine PHB-based TENG, respectively. Also, the bio-TENG exhibits admirable signal stability in over 20000 cycles. Despite the high hardness of CNC/PHB, a soft but simple-structured arch sensor is successfully assembled using CNC/PHB-based TENG. It can attain the precise real-time monitoring of various human motions. This study may provide new insights into the design/fabrication of green functional materials, and initiate the next wave of innovations in eco-friendly self-powered devices.

Enhanced mechanical, barrier and antioxidant properties of rice protein/sodium alginate-based films by incorporating cellulose nanocrystals and rosemary extract

This study aimed to develop rice protein (RP)/sodium alginate (SA)-based biodegradable films with excellent properties by incorporating cellulose nanocrystals (CNCs) and rosemary extract. Effects of the RP/SA weight ratio and CNCs content on the physical properties of the films were investigated, and the improved performance was illustrated by Fourier Transform Infrared spectroscopy and molecular dynamics (MD) simulation. As the RP/SA weight ratio varied from 5:0–1:1, the tensile strength (TS) of the films was increased by 143%, water vapor permeability (WVP) and oil permeability were significantly reduced by 22% and 99.2%, respectively. As the CNCs content increased to 0.3%, the TS was enhanced by 51% and the WVP was reduced by 14%. The improved mechanical and barrier properties of the films were possibly attributed to the formation of a more homogeneous and compact structure observed by scanning electron microscopy. In addition, MD simulation results revealed that there were high number of hydrogen bonds and strong electrostatic interactions in the RP/SA/CNCs/RE system, which may also lead to the improvement of mechanical and barrier properties of films. Finally, the films effectively attenuated oil oxidation. The developed films with enhanced properties are potential food packaging materials.

Water-in-water emulsion stabilized by cellulose nanocrystals and their high enrichment effect on probiotic bacteria

HypothesisThe effect of the molecular weight and polymer concentration on the partition behavior of aqueous two-phase systems (ATPs) is significant for constructing water-in-water (W/W) emulsions. Hence, a long-term stable W/W emulsion system might be obtained through selecting the appropriate stabilizer and component phases, which could be a possible carrier for probiotics. ExperimentsCompared with the reported molecular weight difference between polyethylene oxide (PEO) and dextran (DEX) systems, PEO and dextran with lower molecular weight had been used for constructing the water in water (W/W) emulsion system. The W/W emulsions were stabilized using cellulose nanocrystals (CNCs), and the potential application of the W/W emulsion for the encapsulation of Lactobacillus was explored. FindingsEmulsion stability exhibited a “dose-effect” relationship with the CNCs concentration and was decreased with the increase of the DEX concentration. The emulsion phase separation rate was increased with increasing ionic strength and temperature. Both Lactobacillus Plantarum and Lactobacillus helveticus were highly inclined to the DEX phase, and the emulsion droplets were deformed and aggregated when the encapsulation amount was increased. This long-term stability would provide a promising approach for designing high-density culture and fermentation of probiotics.

Enhancing the Mechanical Properties of 3D-Printed Waterborne Polyurethane-Urea and Cellulose Nanocrystal Scaffolds through Crosslinking.

In this work, shape-customized scaffolds based on waterborne polyurethane-urea (WBPUU) were prepared via the combination of direct ink writing 3D-printing and freeze-drying techniques. To improve the printing performance of the ink and guarantee a good shape fidelity of the scaffold, cellulose nanocrystals (CNC) were added during the synthesis of the WBPUU and some of the printed constructs were immersed in CaCl2 prior to the freeze-drying process to promote ionic crosslinking between calcium ions and the polyurethane. The results showed that apart from allowing the ink to be successfully printed, obtaining scaffolds with good shape fidelity, the addition of the CNC resulted in a greater homogeneity of the porous structure as well as an increase of the swelling capacity of the scaffolds. Additionally, the CNC has a reinforcement effect in the printed systems, presenting a higher compression modulus as the CNC content increases. In the case of samples crosslinked by calcium ions, a rigid shell was observed by scanning electron microscopy, which resulted in stiffer scaffolds that presented a lower water absorption capacity as well as an enhancement of the thermal stability. These results showed the potential of this type of post-printing process to tune the mechanical properties of the scaffold, thus widening the potential of this type of material.

Internal freezing and heat loss of apple (Malus domestica Borkh.) and sweet cherry (Prunus avium L.) reproductive buds are decreased with cellulose nanocrystal dispersions.

Cold damage has caused more economic losses to fruit crop growers in the U.S. than any other weather hazard, making it a perennial concern for producers. Cellulose nanocrystals (CNCs) represent a new generation of renewable bio-nanomaterials, with many unique physical and chemical properties, including their low thermal conductivity. Our team has developed a process for creating CNC dispersions that can be sprayed onto woody perennial crops, forming a thin insulating film around buds which has been shown to increase cold tolerance. Using digital scanning calorimetry (DSC) on dormant apple (Malus domestica Borkh.) reproductive buds, we investigated the thermodynamic properties of plant materials treated with CNC dispersion at lower temperatures. Scanning electron microscopy (SEM) was used to evaluate the thickness of the CNC films and their deposition on the sweet cherry bud surface. Apple buds treated with 3% CNC exhibited lethal freezing at temperatures 3.2°C and 5.5°C lower than the untreated control when sampled 1 and 3 days after application, respectively. Additionally, the latent heat capacity (J/g) of the 3% CNC-treated buds was 46% higher compared with untreated buds 1 day after application, and this difference increased 3 days after application to 168% higher. The emissivity of cherry buds treated with 3% CNC was reduced by an average of 16% compared with the untreated buds. SEM was able to detect the dried films on the surface of the buds 3 days after application. Film thickness measured with SEM increased with material concentration. The emissivity, HTE, and LTE results show that CNC-treated reproductive buds released thermal energy at a slower rate than the untreated buds and, consequently, exhibited internal ice nucleation events at temperatures as much as 5.5°C lower. The increased enthalpy during the LTE in the CNC-treated apple buds shows more energy released at lethal internal freezing, indicating that CNC coatings are increasing the amount of supercooled water. The effects of CNC shown during the DSC tests were increased by CNC concentration and time post-application. These results suggest that CNC dispersions dry into nanofilms on the bud surface, which affects their thermodynamic processes at low temperatures.

Thermally Induced Gelation of Cellulose Nanocrystals in Deep Eutectic Solvents for 3D Printable and Self-Healable Ionogels

Soft ionotronics with self-healing capability and tough mechanical properties are highly desirable for wearable sensors that monitor physiological signals. Rapid prototyping by 3D printing further expands design spaces to enhance the performance of wearable sensors. However, it remains a challenge to achieve printability, mechanical toughness, and self-healing capability simultaneously. Here, we demonstrated a simple route to 3D printable ionogels by thermally induced gelation of cellulose nanocrystals (CNCs) in a deep eutectic solvent (DES). Although DES has been used as a nonvolatile and ionic conductive medium for ionogels, a large quantity of CNCs has to be dispersed in DES to achieve the ideal rheological behavior required for the direct ink writing process. Our strategy significantly reduced the concentration of CNCs needed to prepare printable inks with strong physical networks in DES by triggering the desulfation of CNCs at high temperatures. Further, photopolymerization of acrylic acid and acrylamide with Al3+ ions in the composite inks led to ionogels that contained multiple types of dynamic bonding. Compared with common hydrogels, our DES ionogels exhibited high mechanical toughness and self-healing capability to extend the lifetime of ionotronics. The ionogels were then printed as triangular lattice structures to increase the sensitivity of wearable sensors. In short, we demonstrated a strategy to fully utilize renewable nanomaterials, CNCs, for robust wearable ionotronics.

Fully bio-based CO2-responsive pickering gel emulsions stabilized by cellulose nanocrystals combined with a rosin-based surfactant

A CO2-responsive bio-based surfactant, N-decyl-maleimidepimaric acid N, N-dimethylenediamide bicarbonate (C10MPAN+), was synthesized from rosin. C10MPAN+ showed excellent CO2-responsive properties. Novel CO2-responsive soybean oil-in-water Pickering gel emulsions were further prepared using C10MPAN+ combined with cellulose nanocrystals (CNCs). Due to the strong hydrogen bonds and electrostatic interactions, C10MPAN+ could firmly absorb on the surface of CNCs. The C10MPAN+&CNCs could form a rigid shell on the water/oil interface, resulting in the stable Pickering emulsions. Demulsification could be easily achieved upon bubbling N2 into the emulsions. The microstructure, size distribution, viscoelasticity, and stability of the Pickering emulsions were investigated using a laser particle size analyzer, an optical microscope, and rheology. Emulsions prepared by C10MPAN+&CNCs showed no obvious coalescence or phase separation over 3 months. Importantly, Pickering gel emulsions were formed at C10MPAN+concentration higher than 1 mM. The viscoelasticities of the emulsions were enhanced with the increase of C10MPAN+ concentration and CNCs content. In addition, after five cycles of emulsification/demulsification by alternative bubbling CO2/N2, the Pickering gel emulsions exhibited less difference on the droplets size and viscoelasticity. This work provides a fully bio-based responsive Pickering gel emulsion, and promotes the exploitation and utilization of biomass resources.

Fabrication of Poly(Vinyl) Alcohol-Cellulose Nanocrystal Hybrid Aerogel

In this paper, a series of polyvinyl alcohol (PVA) aerogels hybrid with cellulose nanocrystal (CNC) was successfully prepared using freeze-drying process. The influence of different fractions of CNC and crosslinking agent; glutaraldehyde (GA) on the mechanical of PVA/CNC hybrid aerogels property was evaluated by means of compressive strength. Results show that the mechanical property of hybrid aerogels has been improved with the addition of CNC and GA. Variation in the CNC and GA content also led to differences in the porous structure morphologies. Nevertheless, higher content of GA caused adverse effect to the strength of hybrid aerogel which associated to the excessive crosslinking and smaller number of pores formation as evident from scanning electron microscopy (SEM) analysis.

Comparison of Techniques for Drying Cellulose Nanocrystal Pickering Emulsions into Oil Powders

A recent push for surfactant-free products driven by environmental awareness has propelled the use of bio-based materials in place of petroleum-derived components. However, both the formulation and processing need to be considered for scale-up feasibility and environmental sustainability. This work investigated the drying of corn oil-in-water emulsions stabilized by cellulose nanocrystals (CNCs), methyl cellulose (MC), and tannic acid via freeze drying, spray freeze drying, and spray drying. All three techniques produced oil powders with low moisture content and high encapsulated oil content (>90%). The oil powders could be redispersed in water by hand shaking to reform the original emulsion and could be stored dry for weeks without oil leakage (in the fridge). The release of oil from the powders on hydrophobic substrates (at room temperature) was controlled by changing the CNC and MC stabilizer content; the spray freeze dried samples were the most tunable. The three drying techniques imparted different surface morphologies that were linked to powder redispersibility and oil release properties. The lack of freezing (and associated ice crystal growth) in spray drying minimized oil droplet agglomeration, and it was the fastest, most scalable, and least energy-intensive drying technique of the three, but it was also the most sensitive to emulsion concentration and susceptible to instabilities associated with high temperature and shear stress. It was demonstrated that essential oils with a range of interfacial tensions and volatilities (e.g., jojoba, lavender, tea tree oil) could also be encapsulated in spray dried oil powders. This general encapsulation strategy can be tailored based on the drying technique selected, uses plant-based industrially-produced feedstocks, works with commercially relevant oils, and will hopefully contribute to the development of sustainable emulsions and oil powders for food, pharmaceutical, agricultural, and cosmetic applications.

Production of cellulose nanocrystals extracted from Pennisetum purpureum fibers and its application as a lubricating additive in engine oil

In the present work, cellulose nanocrystals (CNCs) were successfully produced from the Pennisetum purpureum (PP) fibers through ammonium persulfate (APS) oxidation. The effect of oxidation temperatures (60, 70, and 80 °C) on the properties of CNCs was characterized. In addition, the influence of CNCs addition (0, 0.05, 0.1, and 0.2 wt%) on the lubrication properties of the base oil SAE 40 lubricant was also investigated. The characteristics of the CNCs were determined by using FT-IR, XRD, TEM, and TGA. The lubrication properties were evaluated using kinematic viscosity and viscosity index measurements. The optimal oxidation temperature was found at 60 °C which resulted in the needle-shaped CNCs particles with high crystallinity (66.56%), an average diameter (15 nm), and an average length (79 nm). The resulting CNCs exhibited higher thermal stability than the PP fibers. Both kinematic viscosity and viscosity index did not significantly change by increasing the CNCs contents. However, a slightly higher viscosity index was exhibited for 0.2 wt% CNCs compared to that of neat base oil SAE 40. The CNCs obtained had high potential as a reinforcing agent of nanocomposites and also as a bio-lubricating additive in engine oil.

Bio-Nanocomposite Films Based on Cellulose Nanocrystals Filled Polyvinyl Alcohol/Alginate Polymer Blend

In this work, the Juncus plant was used as an abundant and sustainable raw material for the production of cellulose nanocrystals (CNC). Herein, cellulose nanocrystals were prepared via sulfuric acid hydrolysis exhibiting a needle-like shape morphology, with an average diameter of 6.8 ± 1.8 nm and length of 457 ± 76 nm, arising to an aspect ratio of 59. Moreover, X-ray diffraction and TGA show that the CNCs exhibit high crystallinity and good thermal property respectively compared to other sources. Further investigation was conducted by preparing novel bio-nanocomposites through the incorporation of CNCs into the polyvinyl alcohol- alginate (PVA-ALG) blend matrix. Thus, giving enhanced properties compared to the pure matrix, particularly the mechanical properties due to the good interfacial adhesion, confirmed by FTIR analysis, while maintaining good transparency at low CNCs concentration, which is required for packaging application.

A simple and rapid method for the diameter detection of cellulose nanocrystals via sedimentation method

The diameter of nanocellulose most often is detected using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and other related techniques. These detection methods are not only expensive, time-consuming, and complicated to operate, but also are not conducive to the detection of the diameter during the actual production of nanocellulose. In this study, the settling height of cellulose nanocrystals (CNCs) was related to CNC diameter by sedimentation method to find a convenient technique for the rapid detection of CNC diameter. The results showed that when the CNC concentration was at 0.2 wt%, the sodium chloride (NaCl) dosage at 40 g/L, and at the standing time of 48 h, the CNC sedimentation performance was the best. Furthermore, with the increase of CNC diameter, the settling height of CNCs gradually decreased. The relationship between CNC diameter and settling height was Y (Settling height) = -30.17 ln(X (CNC diameter)) + 123.64; and the coefficient of determination for the fit was 0.9965. This research provides a new method for the diameter detection of CNCs in the actual CNCs production in enterprises.

Understanding viscoelastic behavior of hybrid nanocellulose film based on rheological and electrostatic observation in blended suspension

The effects of TEMPO-mediated oxidized cellulose nanofibril (TOCN) on the viscoelastic behavior and phase of cellulose nanocrystal (CNC) in suspension and film were investigated using polarized optical microscopy, rotational rheometry, and dynamic mechanical analysis. The sodium cation from TOCN changed the electrostatic state of CNC by screening the CNC surface charge. The volume inflation of TOCN locally increased the CNC concentration in the suspension. In turn, the CNC–CNC interactions increased the viscosity and the yield stress. Based on the experimental observation, the changing mechanisms of electrostatic state and particular interaction in the TOCN/CNC suspensions were suggested. In the hybrid film, the time dependency of complex moduli was changed owing to the different networking between CNCs and TOCNs. The CNC–CNC contacts easily collapsed by strain, while the TOCN–TOCN entanglements were slowly altered. This study provides a fundamental understanding of CNC behavior for optimizing processes and composite properties.

Cellulose nanocrystal-based enhancement of ultrasound microbubbles for increased tolerance of mechanical index values

Enhancements in the echo intensity and mechanical index (MI) tolerance of ideal ultrasound contrast agents (UCAs) are urgently needed to realize precise clinical ultrasound (US). Solid cellulose nanocrystals (CNCs) have the advantages of imparting strong sound wave propagation and echo intensity when irradiated by US. This study aimed to fabricate improved UCAs via CNC-modified SonoVue ultrasound microbubbles (MBs), characterize the resulting SonoVue@CNC MBs, and evaluate the performance of the SonoVue@CNC MBs in US imaging in vitro and in vivo. SonoVue@CNC MBs were successfully prepared by incorporating CNCs into SonoVue MBs via self-assembly. The SonoVue@CNC MBs were spherical in shape with mean particle sizes of (5.50 ± 1.60) μm. The CNCs were mainly distributed on the polymeric shells of the SonoVue@CNC MBs. When the MI was 0.4, the echo intensity of the SonoVue@CNC MBs was 1.5-fold greater than that of the SonoVue MBs in vitro. The CNC concentration regulated the quality of SonoVue@CNC-promoted contrast-enhanced ultrasound (CEUS) images. Enhanced US images of both the livers and kidneys of Sprague–Dawley (SD) rats showed that the CNC-loaded UCA led to a higher echo intensity than SonoVue. In CCK-8 assays using MCF-10A cells, both SonoVue@CNC MBs and CNCs exhibited weak toxicities against MCF-10A cells. Ultimately, the spherical SonoVue@CNC MBs with a uniform particle size displayed an enhanced safety profile and improved the imaging quality of US in vivo and in vitro. Next, drugs and targeting moieties will be loaded onto the SonoVue@CNC MBs via the CNCs to develop UCA-based selective ultrasonic theranostic methods.Graphical abstractAs shown in the graphical abstract, the white bubble in the left-middle position symbolized SonoVue microbubble (MB), the green rod-like particle signified CNC nanorod. The big white bubble decorated with green rod-like nanorod next to the mouse was SonoVue@CNC MB which was successfully prepared by incorporating CNCs into SonoVue MB via self-assembly. The purple square frame on the upper left displayed CNC, SonoVue MB, SonoVue@CNC MB and their relative diagrammatic drawings. Picture (I) displayed the transmission electron microscopy results for CNCs (a) and SonoVue@CNC MBs (b, c and d) of morphological study. Picture (II) displayed the in vitro ultrasound (US) imaging of SonoVue (a) MB and SonoVue@CNC (b, c and d) MBs with different CNCs concentrations. Picture (III and IV) displayed the in vivo US imaging of SonoVue (a) and SonoVue@CNC (b, c and d) MBs with different CNCs concentrations for SD mouse liver and kidney, respectively.

Incorporation of cellulose nanocrystals and reactive surfactants for improved pressure‐sensitive adhesive performance

AbstractPressure‐sensitive adhesives (PSAs), which achieve instantaneous adhesion with the application of light pressure, are used in a large range of commodity applications. In this work, PSAs enriched with cellulose nanocrystals (CNCs) and stabilized with a reactive surfactant (Hitenol AR‐1025, AR) were synthesized via in situ emulsion polymerization. Incorporation of CNCs into AR‐stabilized PSAs lead to improvements of peel strength, shear strength, and loop tack with significant increases observed at a CNC concentration of 0.75 parts per hundred monomer (phm). A comparative investigation of PSAs stabilized with reactive (AR) and non‐reactive (sodium dodecyl sulfate) surfactant revealed that the enhanced performance can be attributed to the synergistic combination of CNCs and reactive surfactant, as only modest improvements can be attributed to surfactant type. In contrast to previous studies that report a trade‐off in adhesive properties, we present a well‐rounded PSA with exceptional peel strength, shear strength, and loop tack.