Linghan Xiao

Improvement of the thermal conductivity and friction performance of poly(ether ether ketone)/carbon fiber laminates by addition of graphene

Poly(ether ether ketone)/graphene/carbon fiber (PEEK/GE/CF) laminates with different weight percentages of GE were manufactured successfully through ball milling and hot-press processing. The effect of the GE on the morphology, thermal conductivity, friction performance, thermal and mechanical properties of composites was investigated. Scanning electron microscopy showed that the GE was uniformly distributed in matrix-rich regions. Thermal conductivity measurements demonstrated that addition of 0.7 wt% GE sharply improved the thermal conductivity of the laminates. Tribological tests revealed that the friction coefficient and wear rate rapidly decreased with the addition of GE. In the studied range, the friction reduction and wear resistance performance of PEEK/CF composites filled with 0.7 wt% GE is the most effective. Meanwhile, the obtained PEEK/GE/CF laminates also possessed excellent mechanical and thermal properties. Thus, graphene-reinforced PEEK/CF composites possessed better overall properties than conventional PEEK/CF composites.

Tailored synthesis of amine N-halamine copolymerized polystyrene with capability of killing bacteria

Novel amine N-halamine copolymerized polystyrene (ANHCPS) nanostructures were controllably fabricated as potent antibiotics by using the surfactant-free emulsion copolymerization for killing pathogenic bacteria. The morphology and size of the ANHCPS were well tailored by tuning reaction conditions such as monomer molar ratio, temperature, and copolymerization time. Effect of chlorination aging time on the oxidative chlorine content in the ANHCPS was established, and the oxidative chlorine content was determined by the modified iodometric/thiosulfate technique. Antibacterial behavior of the ANHCPS on bacterial strain was evaluated using Staphylococcus aureus and Escherichia coli as model pathogenic bacteria via the plate counting technique, inhibition zone study, and time-kill assay. Antimicrobial results illustrated that the ANHCPS possessed superior antibacterial capability of killing pathogenic bacteria. The destruction induced by the ANHCPS on bacterial surface structure was proven by using SEM technique. The effect of the oxidative chlorine content and morphology/size on the antimicrobial capability was constructed as well. This study provides us a novel approach for controllably synthesizing amine N-halamine polymers, and making them the potent candidates for killing bacteria or even the control of microorganism contamination.

Assessment of 2,2,6,6-tetramethyl-4-piperidinol-based amine N-halamine-labeled silica nanoparticles as potent antibiotics for deactivating bacteria

Novel potent antibiotics, amine N-halamine-labeled silica nanoparticles (ANHLS NPs) based on 2,2,6,6-tetramethyl-4-piperidinol (TMP), were skillfully synthesized via the encapsulation of silica nanoparticles with amine N-halamine polymer for effective killing pathogenic bacteria. The particle size and coating thickness of amine N-halamine of ANHLS NPs were well controlled by tuning size of silica NPs and polymer encapsulation period, respectively. Effect of chlorination time on the oxidative chlorine content in ANHLS NPs was well elucidated by the aid of the modified iodometric/thiosulfate technique. Antimicrobial action of the ANHLS NPs on bacterial strain was evaluated using Staphylococcus aureus and Escherichia coli as model pathogenic bacteria. Bactericidal assessment showed that the ANHLS NPs exerted powerful bactericidal capability toward both two model bacteria. Time-kill assay demonstrated the significance of the oxidative chlorine content and contact time on antibacterial behavior. Size effect experiment displayed the decisive role of the size in controlling the biocidal activity. Plausible antibacterial mechanism of the ANHLS NPs against pathogenic bacteria was also discussed. Such a systematic investigation of the ANHLS NPs provides us a novel idea of making them the promising candidates for deactivating bacteria or even disease control.

Design, synthesis and biocidal effect of novel amine N-halamine microspheres based on 2,2,6,6-tetramethyl-4-piperidinol as promising antibacterial agents

Novel superior antibiotics, i.e. amine N-halamine microspheres based on 2,2,6,6-tetramethyl-4-piperidinol, were first synthesized by the aid of the radical copolymerization for deactivating pathogenic bacteria. The effects of copolymerization period on particle size and copolymer component of the products were elucidated. The oxidative chlorine content in amine N-halamine microspheres was determined by the modified iodometric/thiosulfate technique. The effect of chlorination period on oxidative chlorine content was investigated as well. Bactericidal behaviour of the products on bacterial strain was tested by selecting Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) as model pathogenic bacteria. Antibacterial assessment, including the plate counting technique, zone of inhibition study, and antibacterial kinetic test, demonstrated that amine N-halamine microspheres exerted powerful bactericidal capability. Effects of the contacting period, particle size, and oxidative chlorine content on antimicrobial activity were also established. High stability of amine N-halamine microspheres as a function of soaking period was finally confirmed. Such a systematic investigation of amine N-halamines provides us a novel idea of making them promising candidates for deactivating bacteria and even in disease control.

Improving the interfacial properties of carbon fibers/vinyl ester composites by vinyl functionalization on the carbon fiber surface

A novel “coupling agent” N-(4-amino-phenyl)-2-methyl-acrylamide (APMA) was synthesized to efficiently enhance interfacial interactions between the carbon fiber (CFs) and vinyl ester resin (VE). Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were employed to characterize functional groups and chemical compositions of a carbon fiber surface, which indicated that the vinyl groups of APMA were grafted successfully on the surface of the CFs. Four different treatments of CFs (pristine CFs, carboxylic-CFs, acrylamide-CFs and APMA-CFs) were used to prepare the CF-reinforced VE composites. The mechanical properties were analysed and a micro-droplet test was performed to investigate the enhancement effect of the coupling agent on the interfacial strength of the composites. Scanning electron microscopy (SEM) showed that APMA-CFs were uniformly distributed throughout the matrix, and no open ring holes were found at the cross-section of the composites; furthermore, after micro-droplet test, some matrix was still attached to the debonded CF surface. As a result, APMA functionalized CFs improved the flexural strength of the APMA-CF/VE composites by 19.4%, and significantly improved the interfacial shear strength between APMA-CFs and VE by 90.53%.

Surface arming magnetic nanoparticles with amine N-halamines as recyclable antibacterial agents: Construction and evaluation.

Magnetic recyclable antibacterial nanomaterials, i.e., magnetic amine N-halamine nanoparticles (Fe3O4@SiO2/CTMP NPs), were constructed by arming magnetic silica nanoparticles (Fe3O4@SiO2 NPs) with amine N-halamine (CTMP). Magnetic iron oxide nanoparticles were encapsulated into silica layers followed by anchoring antibacterial amine N-halamines to give magnetic/antibacterial bi-functional agents with core-shell structure. Since the presence of Fe3O4 NPs in core, the products offer super-paramagnetic behavior, which made them separable magnetically after the antibacterial behavior. Their sterilizing effect on bacterial strain was evaluated using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as model bacteria via the plate counting technique, zone of inhibition study, and time kill assay. Antibacterial mechanism study illustrated that the products integrate both the contact mechanism and the release mechanism for attacking bacteria. The significant effect of oxidative chlorine content and concentration of the products on antibiotic action were confirmed. Thanks to the magnetic property, the potential recyclability of the products was achieved. Most significantly, the products retain effective antibacterial action even after five cycles. These findings revealed that the products Fe3O4@SiO2/CTMP NPs have promising applications in the antibacterial fields.

Enhanced tribological performance of PEEK/SCF/PTFE hybrid composites by graphene

Polyetheretherketone (PEEK)/short carbon fiber (SCF)/polytetrafluoroethylene (PTFE)/graphene (GE) composites (PSPGE) with different weight fractions of GE were prepared successfully. The effect of GE on the tribological behavior of PEEK composites was investigated under different applied pressures, sliding speeds and temperatures. Characterization results revealed that the tribological performance was improved with the increase of GE loading, and 2.0 wt% GE filled PEEK/SCF/PTFE composites had the lowest friction coefficient and wear rate. The PSPGE exhibited excellent lubrication and wear resistance efficiency especially under harsh conditions. Moreover, the improved thermal conductivity of the PSPGE composites allowed friction heat to be transferred and further increased the wear resistance. Thus, this newly developed novel PSP2.0GE composite could be applied to many new fields as an advanced friction material.

Improvement of interfacial strength and thermal stability of carbon fiber composites by directly grafting unique particles: functionalized mesoporous silicas

A facile process was used to introduce vinyl functionalized mesoporous silicas onto a carbon fiber to improve the interfacial strength of composites. The characterization of successfully grafted vinyl groups on mesoporous silicas was determined by Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The morphology of the vinyl functionalized mesoporous silicas uniformly distributed on the surface of carbon fiber was characterized by scanning electron microscopy (SEM), which indicated that the homogeneous dispersion of vinyl functionalized mesoporous silicas on a fiber may benefit the interfacial adhesion of matrix. Interfacial shear strength and thermal stability of the composites were improved by increasing the vinyl functionalized mesoporous silicas. This effect arose from the fact that functionalized mesoporous silicas serve as a “rivet joint” produced from chemical bonding and physical interlocking among the mesoporous silicas, carbon fiber and matrix. Notably, introduction of functional mesoporous silicas may be applied for fabricating high performance, multifunctional carbon fiber composites.

Facile synthesis of benzothiadiazole-based chromophores for enhanced performance of second-order nonlinear optical materials

Novel benzothiadiazole-based second-order nonlinear optical (NLO) chromophores with different push–pull structures were developed. Incorporation of benzothiadiazole (BTD) as a bridge for improving the electro-optic (EO) coefficient (r33) of bulky materials has not been well investigated, despite its extensive application in other photonic materials as electron acceptor. NMR and MS have been used to characterize the structure of synthesized chromophores 5–7. Optical properties have been investigated by UV-vis spectra. Density functional theory calculations have been used to calculate the first-order hyperpolarizability (β) of chromophores r1, 5a, 7a and 5b. Moreover, the poling results of guest–host EO polymers, 5a/PC and 5b/PC, afforded good r33 values of 67 pm V−1 and 45 pm V−1, respectively. All the results demonstrated an improvement in both micro- and macroscopic nonlinearity after incorporation of BTD into chromophores.

Preparation of carbon nanotube/copper/carbon fiber hierarchical composites by electrophoretic deposition for enhanced thermal conductivity and interfacial properties

A facile electrophoretic deposition method was proposed to deposit copper (Cu) and carbon nanotubes (CNTs) on the surface of carbon fiber (CF) to improve the thermal conductivity and interfacial properties of carbon fiber-reinforced polymer (CFRP) composites. Surface morphologies, crystallographic properties, thermal conductivity, interlaminar shear strength (ILSS) and element distribution of the composites were characterized by scanning electron microscopy (SEM), X-ray diffraction, thermal constant analysis, short-beam bending tests and SEM energy-dispersive X-ray diffractometer (SEM–EDX), respectively. The results indicate that the presence of Cu and CNTs generated networks and bridges with each other, which produced continuous heat conduction pathways and significantly enhanced both the specific surface area and roughness of the fiber surface. These pathways obviously promoted an improvement in the thermal and interfacial properties. The thermal conductivity and ILSS of the CNTs–Cu–CF/epoxy composites increased by 292 and 39.5%, respectively, compared with CF/epoxy composites. Therefore, this method is anticipated to be utilized in the future fabrication of multifunctional CFRP composites.