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The surface functionalization of CNCs and the construction of strong interfacial adhesion between CNCs and rubber matrix are effective way to achieve high performance rubber/CNCs nanocomposites. Herein, carboxylation of sulphated cellulose nanocrystals (CNC-OSO3H) was conducted in aqueous medium by using citric acid as modifier. Large amount of carboxyl groups was successfully grafted on the surface of CNC-OSO3H, which endows the carboxylated CNC-OSO3H (abbreviate as CNC-CA) with higher chemical reactivity and thermal stability. Subsequently, carboxylated styrene butadiene rubber (XSBR)/CNC-CA nanocomposites with dual crosslinking design were prepared by using polyethylene glycol diglycidyl ether (PEGDE) as the crosslinking agent and CNC-CA as the reinforcing fillers. FTIR investigation found that in the obtained nanocomposites, the carboxyl groups on CNC-CA and XSBR formed hydrogen bonds (physical crosslinking) with each other, and the carboxyl groups formed covalent bond with the epoxy group on PEGDE simultaneously. The coexistence of physical and chemical crosslinking improved the interface compatibility between CNC-CA and XSBR matrix, accelerated the homogenous dispersion of CNC-CA and realized the crosslinking of the matrix itself. As expected, XSBR/CNC-CA nanocomposites with dual crosslinking network showed remarkable enhancement in tensile strength (up to 500%), modulus (up to 151%), work of fracture (up to 348%). This work provides both a facile and green approach to obtain carboxylated CNCs and a convenient method for the preparation of high-performance rubber nanocomposites with multiple interactions.

Rod-like cellulose nanocrystals (CNCs) show the intriguing liquid crystal self-assembly ability. The understanding of the self-assembly behavior of CNCs is of fundamental importance for constructing cellulose-based functional materials. The presented work explores how the liquid crystal self-assembly behavior of CNCs is affected by the grafted ionic liquids (IL) [VBIm][BF4]. The results demonstrate that the IL modified CNC (CNC-IL) with positive charged form chiral nematic structure in suspensions, which was normally observed in negative charged ones. Significantly, such liquid-crystalline organization can be obtained under much lower concentration (as low as 1.0 wt%) than that of the non-functionalized CNCs prepared from paper pulp (~ 3.0 wt%). Moreover, for CNC-IL concentrations varying from 1.0 to 4.0 wt%, the tactoids (showing obvious fingerprint texture) coexist with the disordered CNC phase, rather than separating into two phases. Unlike original CNCs, the pitch of chiral nematic tactoids increases with increasing concentration of CNC-IL. Our study suggests that the distinct liquid crystal self-assembly behavior of CNC-IL is related to the restricted mobility of CNCs rods due to the increase in CNCs particle size and the high viscosity of CNC-IL suspension as the result of IL surface modification. The study of the liquid crystal assembly behavior of IL modified CNCs provides some new insight to understand the intriguing chiral nematic self-assembly of CNCs and for construction of CNC-IL reinforced nanocomposites.

Nowadays, high performance and functional low-dimensional nanomaterials have been targeted in modern sustainable energy science for diverse potential applications. However, broad applications of emerging nanomaterials such as graphene and biomass nanofillers have suffered from low preparation efficiency, low quality of products, unstable dispersion in matrix. In this study, a 100% yield of low-oxidized graphene/nanocellulose hybrids (LGENC) was prepared by one-pot ball milling. Low-oxidized expanded graphite (LOEG) and microfibrillated cellulose (MFC) were used as precursors for fabricating LGENC by the co-exfoliation strategy. That is, exfoliation of LOEG, nanofibrillation of MFC and their hybridization were simultaneously realized under the shear and collision of balls milling. The concentration of LGENC suspension can be concentrated to 50 mg/mL, which has great potential for 3D printing. A series of characterization identified the hybridization of low-oxidized graphene (LGE) and nanocellulose via hydrophobic and hydrogen bond interaction, and confirmed that the LGE has fewer oxygen functional groups and more complete structure than graphene oxide. Benefiting from the intact structure, the conductivity of LGENC can reach up to ~5800 S/m. In addition, the as-prepared LGENC showed significant potential in reinforcing rubber latex. In general, this study proposes a high-efficiency preparation method for graphene/cellulose hybrid materials with extraordinary properties.

Bio-inspired citrate-hydroxyapatite (HAP) nanoparticles doped with zinc ions were prepared from mussel shells via a rapid method of ultrasonication and microwave irradiation. It was found that zinc ions can interact with citrate ions in the crystallization process of HAP. The growth of nanocrystals in citrate solution was slower than that in HCl solution. The addition of zinc ions reduced the residue of citrate in the products and increased the crystallinity of HAP. Furthermore, mineral platelets with the length of 29 ± 7 nm and the thickness of 3–5 nm were obtained for Zn/(Zn+Ca) = 5 mol%, which displayed similar morphology with HAP platelets in bone. Moreover, the obtained HAP nanoparticles are promising for use as bone graft materials in biomedical applications.

In this study, a biomimetic method was used to prepare hydroxyapatite (HAP) and zinc substituted HAP (ZnHAP) nanoparticles, in which silk fibroin was used as template. The morphology of HAP is rod-like, while ZnHAP changes to wrinkled sheets. HAP and ZnHAP nanoparticles were used to coat titanium by EPD with additional chitosan and multiwalled carbon nanotubes. Phase composition, morphology and structure were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared and Raman spectroscopy. The results showed that the composite coatings containing HAP and ZnHAP had homogeneous morphology and good apatite formation ability. The ZnHAP composite coating possessed class 5B adhesive strength using tape test. Furthermore, the ZnHAP composite coating had better corrosion resistance compared to the HAP composite coatings.

A silk fibroin/poly (vinyl alcohol) porous scaffold with a water vapor transmission rate of 2125 ± 464 g/m(2)/day has been developed via thermally induced phase separation (gelation) and freeze-drying process. A hierarchical architecture of micropores and nanofibers was observed inside the scaffolds, and the related structures were analyzed. The viability and proliferation of 3T3 fibroblasts were examined, which indicated that the scaffolds exerted low cytotoxicity. After loading curcumin, the scaffolds can suppress the growth of 3T3 fibroblasts. The release behavior of curcumin from the scaffolds was investigated. At pH = 7.2, the release profiles showed no significant difference for the loading amounts of 0.5 mg and 0.25 mg per sample. Meanwhile, the cumulative amount of released drug at pH = 5.7 was significantly more than that in neutral solution due to more degradation of the scaffolds. It was suggested that the silk fibroin/poly (vinyl alcohol) blend scaffolds could be potentially used as wound dressing materials.