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Shape-stable solid–solid phase-change material (PCM) has attracted much attention due to its excellent thermal properties and shape stability. In this study, cellulose nanocrystal (CNC) was introduced as a high thermal-conductivity nanoskeleton material, and polyethylene glycol (PEG) was used as a solid–liquid phase-change functional material. A green, simple aqueous phase radical polymerization method was used to synthesize shape-stable CNC-based solid–solid phase-change material. The effect of different reaction times on the chemical structure, crystallization ability, thermal stability, and phase transformation properties of the PCM was investigated. All PCM samples showed excellent thermal stability when the temperature was lower than 300 °C. In particular, the synthesized PCM at 12 h had a melt phase transition temperature of 47.1 °C and a phase transition enthalpy up to 82.3 J/g. In addition, the phase-change enthalpy and temperature of PCM-12h did not change significantly after 120 heating and cooling scans. The PCM-12h showed thermal reliability, shape stability, controlled phase-change behaviors, and good heat storage/release properties after thermal treatment. The PCM has potential applications in smart heat storage and temperature control textiles/clothes, building insulation materials, and other energy storage fields. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, we report novel sheet-like cellulose nanocrystal-zinc oxide nanohybrids (CNC-ZnO) by using a one-step hydrothermal method. Various concentrations of Zn2+ ions were functionalized in CNC surface and a possible mechanism for the formation of CNC-ZnO nanohybrids with hexagonal sheet-like structure converted to the flower-like structure was also presented. Additionally, the sheet-like CNC-ZnO5.0 showed good antimicrobial activity, excellent thermal stability and high photocatalytic activity of 95.21% of methylene blue dye was decomposed after 200 min under UV light irradiation. More significantly, the CNC-ZnO5.0 nanohybrid can be recycled three times with good Turnover frequency values. Compared to pure CNC, the maximum degradation temperature (Tmax) of sheet-like nanocrystal-zinc oxide nanohybrid with the addition of 5 mmol Zn2+ ions (CNC-ZnO5.0) nanohybrid was improved by 23.1 °C, and its limiting oxygen index increased up to 49.6%. This work provides a simple preparation procedure of sheet-like CNC-ZnO nanohybrids with good antimicrobial, photocatalytic and thermal properties for attractive applications as biomedical materials and flame-retardants.Graphical abstract: [ABSTRACT FROM AUTHOR]

Ternary nanocomposites including cellulose nanocrystals/silver nanohybrids (CNC-Ag) and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were prepared by using solution casting. The effect of different AgNPs contents in the nanohybrids on crystallization ability and properties of PHBV was comprehensively investigated. Compared to binary PHBV/CNC nanocomposite, the ternary nanocomposites with high AgNPs contents showed larger improvements in the thermal stability, mechanical, barrier, overall migration and antibacterial properties. The property transitions at various AgNPs contents were due to transition of the nanohybrids induced PHBV crystallization ability (from single CNC nucleation to synergistic nucleation of CNC and AgNPs), and increased crystallinity without compromising the amounts of hydrogen bonds. Especially, the PHBV/CNC-Ag-1.7 showed the good barrier property and lower migration levels in food simulants, high antibacterial ratio of 99.9% and biocompatibility to human MG-63 cells, suggesting its potential application in food packaging related materials. [ABSTRACT FROM AUTHOR]

Positively charged and non-toxic intermediate layers are highly desirable for the construction of nanofiltration membranes in the field of Mg2+/Li+ separation. Herein, we have prepared dual-electric layer nanofiltration membranes via introducing positively charged quaternized cellulose nanocrystals (Q-CNC) beyond the negatively charged polyamide skin layers. On the one hand, the strong interactions between Q-CNC and piperazine (PIP) could regulate the thickness, roughness, and residual groups of the polyamide (PA) layers, resulting in improved water flux. On the other hand, the Q-CNC has lots of positive charges which are beneficial for enhancing the rejections of negatively charged polyamide skin layers towards divalent cations since the Donnan and electrostatic effects are long-range forces. Moreover, this effect could be amplified by reducing the thickness of skin layers or decreasing the contents of residual carboxyl groups via adjusting the monomer concentrations. The obtained nanofiltration membranes possess high water flux of 51 L/m2/h/bar, and rejection for MgCl 2 of 86 %. The separation factor of Mg2+/Li+ is 29 when the Mg2+/Li+ mass ratio in the feed solution is 20:1. Moreover, the nanofiltration membrane with Q-CNC intermediate layers (QNFM) has good antibacterial properties, showing great potential in the fields of lithium extraction from salt lakes. [Display omitted] [ABSTRACT FROM AUTHOR]

Double stimuli-responsive functionalized cellulose nanocrystal-poly[2-(dimethylamino)ethyl methacrylate] (CNC- g -PDMAEMA) reinforced poly(3-hydroxybutyrate- co -3-hydroxy valerate) (PHBV) electrospun composite membranes were explored as drug delivery vehicles using tetracycline hydrochloride (TH) as a model drug. It was found that rigid CNC- g -PDMAEMA nanoparticles enhanced thermal, crystallization and hydrophilic properties of PHBV. Moreover, great improvements in fiber diameter uniformity, crystallization ability and maximum decomposition temperature (T max) could be achieved at 6 wt% CNC- g -PDMAEMA. Furthermore, by introducing stimuli-responsive CNC- g -PDMAEMA nanofillers, intelligent and long-term sustained release behavior of composite membranes could be achieved. The releasing mechanism of composite membranes based on zero order, first order, Higuchi and Korsmeyere-Peppas mathematical models was clearly demonstrated, giving effective technical guidance for practical drug delivery systems. Electrospun PHBV composites membrane with double stimuli-responsive cellulose nanocrystal tailor drug release at human physiological condition for long-term sustained drug delivery. Unlabelled Image • Functionalized cellulose nanocrystals gave double stimuli-responsive performance. • Composite membrane has intelligent drug release ability at human physiological condition. • Composite membrane shows faster drug rate at pH = 5 for potential tumor cell targeting. • Four releasing mechanism of composite membranes have been clearly demonstrated. [ABSTRACT FROM AUTHOR]

A novel chemical reduction method was reported to prepare tunable spherical or belted morphologies of nano-selenium (Se) based on cellulose nanocrystal (CNC). The homogeneous Se nanospheres with size of about 36 nm can be found for Se-Sphere-12H by adding ascorbic acid (VC) as assisted reducing agent. The Se nanobelt with a length of about 800 nm can be observed for Se-Belt-12H through one-pot reaction of CNC with sodium selenite (Na 2 SeO 3 ) under hydrothermal conditions. Moreover, Se-Belt-12H exhibited the higher crystallinity of 96.10% and maximum thermal degradation temperature (T max ) of 479.4 °C, the highest capacitance and the smallest internal resistance. [ABSTRACT FROM AUTHOR]

Fabrication and characterization of bbiodegradable nanocomposites based on poly (3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) matrix reinforced with cellulose nanocrystal (CNC)-ZnO nanohybrids via simple solution casting for possible use as antibacterial biomedical materials is reported. The obtained nanocomposites exhibited an excellent antibacterial ratio of 95.2–100% for both types of bacteria namely S. aureus and E. coli and showed 9–15% degradation after one week. The addition of CNC-ZnO showed a positive effect on hydrophilicity and barrier properties. More significantly, the nanocomposites with 10 wt% CNC-ZnO showed enhancement in tensile strength (140.2%), Young’s modulus (183.1%), and the maximum decomposition temperature (T max ) value increased by 26.1 °C. Moreover, this study has provided a possible mechanism for using such nanofillers on the hydrolytic degradation of PHBV, which was beneficial to obtain the high-performance nanocomposites with modulated degradation rate for antibacterial biomaterials. [ABSTRACT FROM AUTHOR]

The conventional skin sensor detection of human physiological signals can be an effective method for disease diagnosis and health monitoring, but the poor biocompatibility, low sensitivity and complex design largely limit their applications. Developing natural nanofiller-reinforced composites as strain biosensors is an appealing solution to reduce environmental impacts and overcome technical bottleneck. Herein, a versatile nature skin-inspired composite film as flexible strain biosensor was developed based on cellulose nanocrystals-polyaniline (CNC-PANI) composites by utilizing their percolated conductive network in polyvinyl alcohol (PVA) matrix. The composite electronic skin showed robust mechanical strength (50.62 MPa) and high sensitivity (Gauge Factor = 11.467) with easy water-induced self-healing abilities. Moreover, we investigated the functioning mechanism of percolated network and the sensory behavior determined by CNC nanocomposite alignment. The percolation threshold of CNC-polyaniline (PANI) was determined at 4.278% and 5% CNC-PANI composite film shows the best overall sensing property. It was also discovered that the sensitivity of this type of conductive-filler electronic skin can be divided into two separate regions at different strain range due to its percolated network. With films prepared by dry casting and dip coating, the alignment of CNC-PANI also contributes to this unique change in electrical property. Generally, our results demonstrated the mechanism and tunability of conductive nanofiller-based composite strain biosensors as a potential alternative to commercial synthetic sensors. • Conductive cellulose nanocrystals incorporated PVA composite strain biosensor were prepared. • The self-healed composite showed robust mechanical strength and excellent sensitivity. • Working mechanism of percolated network-based conductivity and sensitivity was reported. • Self-healing mechanism of PVA nanocomposite film was proposed. [ABSTRACT FROM AUTHOR]

• Magnetic cellulose nanocrystals hybrids reinforced PCF composites were prepared. • Dipole responsive magnetic/solar driven thermal energy storage of PCF composites have reported. • PCF composite exhibited magnetic or solar thermal energy storage efficiencies of 32.1 and 58.6 %. • The PCF composites showed excellent thermal performance and shape stability. • The PCF composites can be used as an integrated collector for potential fruits dryer devices. The intrinsic intermittence of solar energy raises the necessity for thermal energy storage (TES) systems to balance the contradiction between energy supply and demand energy. This work experimentally provides solid-liquid phase change materials (PCMs) with sufficient storage capacity and discharging rate to offer heating for agriculture products by enhancing heat transfer in phase change fiber composites (PCF). To achieve this, we prepared dipole responsive magnetic/solar-driven PCF composites reinforced with magnetic cellulose nanocrystals hybrids (M CNC). The obtained PCF/ M CNC-5% showed excellent magnetic property with a saturation magnetization (MS) value of 1.3 emu/g and effective latent heat phase change enthalpies of 69.2 ± 3.5 J/g – 83.1 ± 4.2 J/g. More importantly, PCF/ M CNC-5% showed robust high magnetic to thermal energy storage efficiency of 32.5 % and solar light accelerated energy storage efficiency of 58.5 %. These advantages make the PCF composites promising and more desirable for drying and preservation of the fruits and other agriculture products. [ABSTRACT FROM AUTHOR]

• Synthesis of bimetallic silver-gold NPs was realized in a cellulose dope. • The dissolved cellulose played as reductant and support matrix for the NPs. • Structure of the NPs was facially tuned by adjusting the feeding operations. • Correlation of bioactivity with nanostructure of the NPs was investigated. • Flexible cellulose decorated with the NPs endowed its efficient SERS activity. Introducing functional metal nanoparticles (NPs) into flexible substrate is being increasingly attempted to expand their application. Here, we extend the synthesis of cellulose to its unmodified dope achieving freestanding nanocomposite decorated with bimetallic Ag-Au NPs through the one pot reaction. In the procedure, cellulose chain not only acts as a reducing agent but also a biocompatible support for NPs with a mean size of 7.9–9.7 nm. Meanwhile, changing the addition order of Ag+ and AuCl 4 − generated different atom arrangement in the bimetallic NPs. Moreover, the correlation of bioactivity to NP atom arrangement was studied. The result revealed that the nanocomposite containing NPs with an ultrathin Ag-rich outermost shell around an Au-rich core showed better bactericidal ability while lower cytotoxicity. In addition, the nanocomposite exhibited a sensitive SERS property for determination of R6G with a high enhancement factor of 108. [ABSTRACT FROM AUTHOR]

• Supermagnetic hybrids were successfully synthesized by using CNCs as templates. • Synergistic reinforcing effect of CNCs and Fe 3 O 4 on PHBV performances were observed. • M CNC hybrids can be used as an indicator to detect water vapor. • M CNC reinforced nanocomposites offer a real-time monitoring method for water vapor. • The nanocomposites show great potentials in bioactive and smart packaging materials. In this work, cellulose nanocrystals (CNCs) incorporated with supermagnetic iron oxide nanoparticles (Fe 3 O 4 NPs) as (M CNC) hybrids by the co-precipitation method have developed. High-performance nanocomposite films consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) and M CNC hybrids have prepared through a simple solution casting method. The addition of CNCs in M CNC-5% hybrids improved the surface hydrophilicity of PHBV, and displayed a reduction in water vapor permeability by 68.1 %, compared with pristine PHBV. The results prove that the addition of M CNC hybrids can be acted like a sensor to detect voltage change of the nanocomposites as functions of water vapor. The existence of CNCs in the M CNC-5% hybrids caused an increase in tensile strength and Young's modulus by 74.6 % and 120.2 %, respectively. The addition of CNCs could enhance cell-matrix interactions and thus cytocompatibility of PHBV nanocomposites. The PHBV/ M CNC-5% exhibited saturation magnetization (Ms) values of 1.5 emu g−1 and displayed almost a regular and operative voltage response signal with real-time monitoring of water vapor. This work provides sustainable smart packaging materials with high sensitivity for water vapor and excellent biocompatibility. [ABSTRACT FROM AUTHOR]

• Smart nonwoven fabric with reversible double-stimulus response wettability was fabricated. • DSR-CZPP can adjust wettability and permeability under various stimulations of pH and UV light. • DSR-CZPP with CNC/ZnO simultaneously degrade organic dyes and tailor oil-water separation. • DSR-CZPP had high removal rates for various pollutants (metal ions, toxic organic solvents). This work presents the first fabrication of smart nonwoven fabric (DSR-CZPP) with extraordinary reversible double-stimulus responsive wettability, where carboxyl groups of cellulose nanocrystals/zinc oxide (CNC/ZnO) nanohybrids deposited on fabric surface can bond with hydroxyl group of the PDMAEMA-b-PHEMA-b-PMAAAB triblock polymer brushes that was prepared by using methyl methacrylate (HEMA), dimethylaminoethyl methacrylate (DMAEMA) and methacrylamide-azobenzene monomer (MAAAB) via reversible addition–fragmentation chain transfer (RAFT). The peculiar reversible double-stimulus responsive wettability of the DSR-CZPP can be modulated by triggering hydrophilic/hydrophobic transitions and lipophilic/oleophobic transitions under dual-stimulations of pH and UV light irradiation. The special molecular structure of the triblock polymer brushes enabled DSR-CZPP to intelligent modulation of oil-water separation under the control of "UV & pH double switch", meanwhile CNC/ZnO simultaneously can induce the photocatalytic degradation of organic dyes. Moreover, DSR-CZPP can have high removal ratios of various pollutants, such as metal ion (Cu2+) and toxic organic solvent (silicone oil, acetone and chloroform). This smart and multifunctional fabric shows great potentials for treating complicated polluted water from most industrial fields. [ABSTRACT FROM AUTHOR]

• Phase change nanofibers (PCF) demonstrated solid–solid phase change performance. • Obtaining PCF composite with excellent shape-stability and energy storage efficiency. • PCF composite shows "on–off" drug release in response to phase change temperature. • PCF composite with 5 wt% f- CNC-ZnO displayed a sustained release of more than 78.9% within 336 h. Thermo/light-responsive functionalized cellulose nanocrystal-zinc oxide (f- CNC-ZnO) nanohybrids based poly (3-hydroxybutyrate-co-3-hydroxy valerate) (PHBV) phase change nanofiber (PCF) composites with highly thermal energy storage ability were developed for controllable drug release applications. Under sunlight irradiation, the PCF composite (without f- CNC-ZnO) absorbed light and stored the thermal energy with 46.3% efficiency. An "on–off" temperature regulation of tetracycline hydrochloride (TH) release was found for PCF composites according to phase change temperature. At the temperature close to the melting point of PEG at 60 °C, the PCF composite with 5 wt% f- CNC-ZnO displayed a sustained release of more than 40.5 and 78.9% of tetracycline hydrochloride (TH) were released over two weeks for the 10 and 30 wt% drug loading. Thus, the PCF composites with excellent thermo/light-responsive properties and high energy storage efficiency are beneficial for promising sustainable thermal storage and drug delivery systems. [ABSTRACT FROM AUTHOR]