In view of its essential activity for antimicrobial, tetra-needle like ZnO (T-ZnO) were used as the carrier for in situ synthesizing well-dispersed nano-copper (n-Cu), to prepare a composite antibacterial agent for improving the activity and broadening the spectrum. The obtained hybridizing materials were characterized by electron microscopic observations, X-ray diffraction and X-ray photoelectron spectroscopic analyses, and the results showed that the n-Cu with an average size of 15 nm were uniformly loaded on surfaces of T-ZnO. The existence of special interactions between copper and T-ZnO was also approved. The as-prepared hybrids displayed much higher activity as compared to the pristine T-ZnO, the n-Cu alone, and even the identical copper amount of CuCl2 solution against Escherichia coli and Staphylococcus aureus. Based on systematically characterization and analyses, we attributed it to the synergistic effect resulted from the structural hybridization between the single-crystalline T-ZnO and n-Cu which lead to the increase of copper ions release and H2O2 generation. This discovery can be developed an effective approach towards a new kind of wide spectrum and high efficiency antibacterial materials.Download high-res image (149KB)Download full-size image

The amphiphilicity of solvent systems is realized for adjusting the dissolution of natural cellulose by making use of tetra-butylammonium hydroxide (TBAH) as an example. TBAH aqueous solution is found to have an obvious effect on adjusting its amphiphilicity, along with a flexible concentration ranging from 40 to 60 wt% for dissolving cellulose. With a suitable amphiphilic property, cellulose can be dissolved by a TBAH aqueous system . The experimental results demonstrate that with the introduction of urea (more than 0.2:1, w:v) into a TBAH aqueous system, the dissolution process of cellulose can be dramatically promoted, leading to a transparent solution of cellulose. Herein, a complex solvent of TBAH/urea has been proposed for mild and effective dissolution of cellulose under ambient conditions. In the TBAH/urea complex solvent, the structure of the hybrid hydrate of TBAH and urea formed. Urea served as a hydrophobic contributor adjusting the amphiphilicity of the solvent system, allowing interfacial resistance between the amphiphilic crystal surfaces of the natural cellulose and solvent to be reduced. After that, the crystal of natural cellulose could be fully infiltrated and subsequently dissolved by the TBAH/urea aqueous solvent. The performances of the aqueous solvent and ambient temperature dissolution make aqueous TBAH/urea a potential and green solvent of cellulose for broad applications, such as composites, films or wet spinning of cellulose, in laboratories or industries.

•Effect of pretreatment of straw fiber on the fiber characteristics was investigated.•Different kinds of straw fibers filled cement based composites were studied.•Pretreatment of straw fiber eliminate amorphous hemicellulose and lignin.•The pretreated rice straw fibers had less influence on the hydration of cement.The morphological and structural characteristics of four different fibers, the pristine rice straw (RF1) and three fibrous materials (RF2, RF3 and RF4) during the components separating process from rice straw, were investigated. The results indicated the pretreatment of rice straw could eliminate amorphous hemicellulose and lignin, increase the crystallinity and improve the thermal stability of rice straw fiber. Additionally, the effect of four kinds of straw fibers on hydration of the straw fiber filled cement based composites were studied using isothermal calorimetry, X-ray diffraction (XRD) and thermogravimetry (TGA) techniques. For this purpose, the composites containing 10 wt.% of the pristine and the pretreated rice straw fiber were prepared. As a result, the presence of both the pristine and the pretreated rice straw fiber delays and inhibits the hydration of cement. The composites containing RF1 showed the lowest rate of heat of hydration (almost 0 mW) and sustained the cumulative heat (7.9 J) compared to the composites containing RF2, RF3 and RF4 (240.1, 318.2 and 317.1 J, respectively) in the first 7 days. However, the cumulative heat of the composites with the pretreated rice straw fibers was still lower than the control cement paste (334.2 J). The XRD and TGA results revealed that the amount of calcium hydroxide is lower in the composites containing rice straw than in neat cement. This study recommends that the pretreated rice straw fibers had less influence on the hydration of cement.

•Magnetic activated carbon (MAC) from peanut shell was prepared via a simple one-step method.•The obtained MAC has the high BET surface areas with a honeycomb-like structure.•The obtained MAC showed a micro-, mesopores and macropores combination with magnet Fe3C.•Activation temperature played the key role in the formation of Fe3C.Magnetic peanut shell based activated carbon (MPSAC) was first prepared via a simple one-step method in the existence of K2CO3 and Fe3O4. The effects of activation temperature and activation time on the structures and properties of the activated samples were analyzed. Results show that the development of the porous structures can be facilitated by increasing the activation temperature or the activation time. Compared with the activation time, the activation temperature was found to play the key role in the formation of magnet Fe3C. At 750 °C for 1.5 h or 800 °C for 1 h, Fe3O4 was almost converted into Fe3C. The prepared MPSAC-750-1.5 and MPSAC-800-1 demonstrated the high surface area with a micro-, mesopores and macropores combination.

Graphene oxide/nylon 11 composites were prepared by in situ melt polycondensation. These composites displayed better mechanical properties including stiffness and toughness than the pure nylon 11 matrix. The enhanced toughness was ascribed to the change of crystal form of nylon 11, namely the triclinic α crystal form to the pseudo-hexagonal δ′ crystal form transition trend with the incorporation of GO. Scanning electron microscopy and transmission electron microscopy images showed that GO bundles and stacks with an average thickness of 20 nm are homogeneously dispersed over the nylon 11 matrix with almost no large agglomerates.

Based on the principles of electrical conduction and transformation, a model was put forward for the electrical conversion of piezoelectric damping composites, and a related formula was derived. The results show that the best effect of conversion can be achieved by reducing the imaginary part of the impedance and matching the frequency. The optimal damping effect at a certain frequency requires resistance of conductive phase (R) satisfying the condition of R=1/(ωC), but this condition may cause the damping effect at other frequencies to deviate away from the optimum condition. It is suggested that in order to make the damping effect more efficient and objective, frequency matching should be considered during the design of piezoelectric damping composites.

The tetra-needle like zinc oxide whisker (T-ZnOw) was treated with γ-aminopropyltriethoxysilane (APTS), a coupling agent of silane with amino-group, to form a protection and bonding layer on its surface, where polyaniline (PANI) was in situ polymerized to form a new kind of core–shell structured T-ZnOw/PANI composites. The structure, morphologies, and conductivity of the synthesized products were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis absorption spectroscopy, etc. The FTIR spectra reveal that the T-ZnOw is successfully modified by APTS and finally forms the T-ZnOw/PANI core–shell structure composites. The SEM results indicate surface modification plays distinct roles both for keeping the intactness of the morphology structure of T-ZnOw and for providing an in situ polymerization site on the surface of the T-ZnOw. The electrical conductivity of the PANI covered T-ZnOw is 7.2 × 10−1 S cm−1, which appears much higher than that of the pure T-ZnOw.

Traditional polymer composites generally present limited thermal conductivity (TC) even highly loaded with highly thermally conductive fillers due to the lack of large interfacial thermal resistance between the fillers and the surrounding polymers. In this work, polyamide-6/graphite nanoflakes (PA6/GnF) composites with high TC can be obtained through a one-step in situ intercalation polymerization. The caprolactam onium ion (CL⊕) catalysted by 6-aminocaproic acid can effectively intercalate into the interlayer of expanded graphite (EG) and lead to the separation of EG into GnF after in situ polymerization. Thereafter the homogeneous dispersions of GnF with ordered arrangement and strong interfacial interactions between PA6 and GnF can be formed within the PA6/GnF composites, which can favor the formation of the consecutive thermal conductive pathways or networks at a relatively low EG loading. The obtained composites, at only EG loading of 12 wt%, exhibit a high TC (2.49 W/mK), corresponding to an enhancement of 678% compared to that of neat PA6. This strategy offers new insights into the fabrication of graphene based composites, and provides a straightforward and highly industrializable process for fabrication of high-performance GnF-based thermally conductive composites.In situ intercalation polymerization approach can lead to an extraordinary increase in thermal conductivity of the polyamide-6/graphite nanoflakes compoaites.