Electroconductive Composites Containing Nanocellulose,Nanopolypyrrole,and Silver Nanoparticles

In this work,conducting composites of nanocellulose(NC)/polypyrrole nanoparticles(NPPy)and silver nanoparticles(AgNPs),i.e.,NC/NPPyAg,were synthesized for the first time,to the best of our knowledge,via in situ emulsion polymerization of pyrrole in the presence of surfactant dopants.The AgNPs acted as an oxidizing agent to simultaneously incorporate nanoparticles into the prepared composites.The structures and morphologies of the prepared composites were studied using Fourier transform infrared(FTIR)spectroscopy,X-ray diffraction(XRD),UV-Vis Spectra,thermogravimetric analysis(TGA),and scanning and transmission electron microscopy(SEM and TEM)techniques.Additionally,the prepared composites were characterized by their conductivities,and the dielectric constants(e΄),dielectric losses(e˝),and AC conductivities were studied for the prepared composites with an increasing NPPy content as a function of the frequency.

Modified Maxwell model for predicting thermal conductivity of nanocomposites considering aggregation

The effect of nanoparticle aggregation on the thermal conductivity of nanocomposites or nanofluids is typically nonnegligible. A universal model（Maxwell model） including nanoparticle aggregation is modified in order to predict the thermal conductivity of nanocomposites more accurately. The predicted thermal conductivities of silica and titania nanoparticle powders are compared first with that measured by a hot-wire method and then with those in previous experimental works.The results show that there is good agreement between our model and experiments, and that nanoparticle aggregation in a nanocomposite enhances the thermal conductivity greatly and should not be ignored. Because it considers the effect of aggregation, our model is expected to yield precise predictions of the thermal conductivity of composites.

A Generic Strategy to Create Mechanically Interlocked Nanocomposite/Hydrogel Hybrid Electrodes for Epidermal Electronics

Stretchable electronics are crucial enablers for next-generation wearables intimately integrated into the human body.As the primary compliant conductors used in these devices,metallic nanostructure/elastomer composites often struggle to form conformal contact with the textured skin.Hybrid electrodes have been consequently developed based on conductive nanocomposite and soft hydrogels to establish seamless skin-device interfaces.However,chemical modifications are typically needed for reliable bonding,which can alter their original properties.To overcome this limitation,this study presents a facile fabrication approach for mechanically interlocked nanocomposite/hydrogel hybrid electrodes.In this physical process,soft microfoams are thermally laminated on silver nanowire nanocomposites as a porous interface,which forms an interpenetrating network with the hydrogel.The microfoam-enabled bonding strategy is generally compatible with various polymers.The resulting interlocked hybrids have a 28-fold improved interfacial toughness compared to directly stacked hybrids.These electrodes achieve firm attachment to the skin and low contact impedance using tissue-adhesive hydrogels.They have been successfully integrated into an epidermal sleeve to distinguish hand gestures by sensing mus-cle contractions.Interlocked nanocomposite/hydrogel hybrids reported here offer a promising platform to combine the benefits of both materials for epidermal devices and systems.

Microstructure and Electrical Conductivity of CNTs/PMMA Nanocomposite Foams Foaming by Supercritical Carbon Dioxide

The carbon nanotubes（CNTs）/polymethylmethacrylate（PMMA）nanocomposite foams were prepared by the anti-solvent precipitation and supercriticalfoaming method.The morphology and the electricalconductivity of the foams with different kinds of CNTs were investigated.The experimentalresults showed that allthe foams had uniform cellstructure,and the cellsize changed from 1.9 to 10 μm when the foaming temperature ranged from 50 ℃ to 95 ℃.With smallcellsize（1.9-4.0 μm）,the conductivities of the foams were 3.34×10^（-6）-4.16×10^（-6） S/cm compared with the solid matrix since the introduction of micro cells did not destroy the conductive network.However,when the cellsize was biger（4.5-10 μm）,the aspect ratio of the CNTs played the dominant role of the conductivity.The foams with short CNTs had higher conductivity,since the short CNTs were hard to stretch and snap by the cells and can well-dispersed in the cellwalland celledges.The results of this work provided a novelmaterialdesign method for conductive foams based on the rule of both microstructure and aspect ratio of the CNTs.

Band gap engineered polymeric-inorganic nanocomposite catalysts:Synthesis, isothermal stability, photocatalytic activity and photovoltaic performance

Polymeric-inorganic nanocomposite catalysts were synthesized by facile one-pot chemical polymerization of pyrrole in the presence of titanium dioxide nanoparticles. The electrical, optical, photovoltaic performance of dye sensitized solar cell（DSSC） and visible light driven photocatalytic activities of the nanocomposite were investigated. The prepared nanocomposite displays excellent photo-activity, attaining 100% degradation of methyl orange dye in 60 min under visible light source while 55% for pure TiO_2 under similar experimental conditions. The photovoltaic performance of the polypyrrole-titanium dioxide（PPy-TiO_2） nanocomposite has a 51.4% improvement with a photo-conversion efficiency of 8.07% as compared to pure TiO_2 based DSSC. By comparing the physical mixture of the PPy-TiO_2 nanocomposite and pristine TiO_2, the enhanced activity of the PPy-TiO_2 nanocomposite can be attributed to the reduced charge transfer resistance, outstanding electrical conductance of the PPy, the nano-sized structure of TiO_2 and their synergetic effect. Furthermore, the PPy-TiO_2 nanocomposite shows excellent electrical conductivity and isothermal stability under ambient conditions below 110？C.