Polymer-Coated Carbon Nanotubes as a Molecular Heater Platform for Hyperthermic Therapy

福岡歯科大学2017年

A multi-redox responsive cyanometalate-based metallogel

A tetrathiafulvalene (TTF) based tridentate ligand (-(4’-methyl-4,5-di-n-dodecylthylthiotetrathiafulvalene-5’-ylthio)-’-[tris-2,2,2-(1-pyrazolyl)ethoxy]-p-xylene) (L) with long-chain alkyl moieties was prepared in order to obtain a new multi-redox active gelator based on a mixed-metal octanuclear complex [FeIII4NiII4(CN)12(tp)4(L)4](BF4)4 (1). The magnetism, electrochemistry and gelation behaviour of 1 were studied and 1,2-dichlorobenzene solutions of 1 are shown to display thermoreversible gelation behaviour at room temperature. Furthermore, the gel phase of 1 is shown to undergo room-temperature gel-to-sol transformations induced by both the oxidation and reduction of the gelator complex by F4TCNQ or [FeII(Cp*)2], respectively

Extremely stable platinum-amorphous carbon electrocatalyst within hollow graphitized carbon nanofibers for the oxygen reduction reaction

Unprecedented electrochemical stabilization of platinum nanoparticles (PtNPs) is presented, upon insertion into shortened hollow graphitized carbon nanofibers (PtNP@S-GNF) toward the oxygen-reduction reaction for fuel-cell applications. In contrast to that observed for a commercial Pt/C electrocatalyst, the specific activity and the electrochemical surface area for PtNP@S-GNF remain practically unchanged during durability tests after 50 000 potential cycles, allowing the sustainable use of Pt

Optimisation of electrophoretic deposition parameters for gas diffusion electrodes in high temperature polymer electrolyte membrane fuel cells

Electrophoretic deposition (EPD) method was used to fabricate gas diffusion electrodes (GDEs) for high temperature polymer electrolyte membrane fuel cells (HT PEMFC). Parameters related to the catalyst suspension and the EPD process were studied. Optimum suspension conditions are obtained when the catalyst particles are coated with Nafion® ionomer and the pH is adjusted to an alkaline range of about 8 e10. These suspensions yield good stability with sufficient conductivity to form highly porous catalyst layers on top of the gas diffusion layers (GDLs). GDEs were fabricated by applying various electric field strengths of which 100 V cm-1 yields the best membrane electrode assembly (MEA) performance. Compared to an MEA fabricated by the traditional hand sprayed (HS) method, the EPD MEA shows superior performance with a peak power increase of about 73% at similar platinum (Pt) loadings. Electrochemical Impedance Spectroscopy (EIS) analysis shows lower charge transfer resistance for the MEA fabricated via the EPD method compared to the HS MEA. The EPD GDE exhibits a greater total pore area (22.46 m2 g-1) compared to the HS GDE (13.43 m2 g-1) as well as better dispersion of the Pt particles within the catalyst layer (CL).Web of Scienc

Photothermally enhanced drug release by kappa-carrageenan hydrogels reinforced with multi-walled carbon nanotubes

Temperature and near infrared (NIR) light responsive multi-walled carbon nanotube (MWCNT)-kappa-carrageenan hydrogel composites have been prepared. The effects of the MWCNTs on the microstructure, strength, swelling and release properties of the resultant materials were investigated. MWCNTs acted as reinforcing fillers and enhanced the mechanical properties of the hydrogels, the effect being mostly nanotube concentration dependent. Surface functionalization of nanotubes had a major influence on the swelling of the composites. The increased release of a model drug (methylene blue) in in vitro conditions, from kappa-carrageenan hydrogel composites due to the NIR photothermal effect of MWCNTs was demonstrated at the physiological temperature. Thus, these composites are promising materials for the development of carriers for remotely activated drug delivery

Thermal Conductivity of Carbon Nanotubes and their Polymer Nanocomposites: A Review

Thermally conductive polymer composites offer new possibilities for replacing metal parts in several applications, including power electronics, electric motors and generators, heat exchangers, etc., thanks to the polymer advantages such as light weight, corrosion resistance and ease of processing. Current interest to improve the thermal conductivity of polymers is focused on the selective addition of nanofillers with high thermal conductivity. Unusually high thermal conductivity makes carbon nanotube (CNT) the best promising candidate material for thermally conductive composites. However, the thermal conductivities of polymer/CNT nanocomposites are relatively low compared with expectations from the intrinsic thermal conductivity of CNTs. The challenge primarily comes from the large interfacial thermal resistance between the CNT and the surrounding polymer matrix, which hinders the transfer of phonon dominating heat conduction in polymer and CNT. This article reviews the status of worldwide research in the thermal conductivity of CNTs and their polymer nanocomposites. The dependence of thermal conductivity of nanotubes on the atomic structure, the tube size, the morphology, the defect and the purification is reviewed. The roles of particle/polymer and particle/particle interfaces on the thermal conductivity of polymer/CNT nanocomposites are discussed in detail, as well as the relationship between the thermal conductivity and the micro- and nano-structure of the composite

Coalescence of Cluster Beam Generated Sub-2 nm Bare Au Nanoparticles and Analysis of Au Film Growth Parameters

In this work is presented the growth model for Au films grown on a carbon substrate at room temperature by using as building blocks Au nanoparticles (NPs) with 1.4 nm mean size generated via remote cluster beam synthesis and soft landing on the substrate. The key results highlighted in this work are that 1) the deposited nanoparticles coalesce at substrate level in such a way that the film growth is 3D, 2) newly formed nanoparticles at substrate level are predominantly magic number clusters and 3) coalescensce takes place as soon as two neighboring nanopartciles come closer than a critical distance. The film growth was investigated by TEM as a function of Au load, in the range 0–1.2 μg/cm2. Two distinct regimes are identified: the “landing regime” and the “coalescence regime”. During the latter the film growth is 3D with a dynamic scaling exponent z of 2.13. Particular attention was devoted to the study of the evolution of the NP population from the moment they are generated with the cluster beam generator to the moment they land on the substrate and coalesce with other NPs. Our results show that 1) the NPs generated by the cluster beam are heterogeneous in size and are made by more than 95% by Au Magic numbers, mainly Au20 and Au55 and 2) kinetic processes (coalescence) at substrate level is capable of producing NPs populations made of larger Au magic numbers containing up to several thousands of Au atoms. Experimental and simulation results provide insight into the coalescence mechanism and provide strong evidence that the NPs coalesce when the nearest neighbor distance is below a critical mark. The critical distance is at its minimum 0.4-0.5 nm and it is still unclear whether it is constant or not although the best matching simulation results seem to point to a superlinear dependence from the NP size difference between two neighboring candidate coalescing NPs. The coalescence phenomenon investigated in this work pinpoints the unique self-organization properties of these small Au NPs in creating films with a stable edge-to-edge mean nearest neighbor distance of the order of 1.4 nm

Carbon Nanotubes on Polymeric Microcapsules: Free-Standing Structures and Point-Wise Laser Openings

Single-wall carbon nanotubes modified by anionic polyelectrolyte molecules are embedded into the shells of microcapsules. Carbon nanotubes serve as rigid rods in a softer polymeric capsule, which forms a free-standing shell upon treatment with glutaraldehyde and subsequent drying. The embedded carbon nanotubes exhibit a broad absorption in the UV–near-infrared part of the spectrum, and that allows point-wise activation and opening of the microcapsules by laser. Raman signal analysis shows changes of carbon-nanotube-specific lines after high-power laser irradiation, which is characteristic of the formation of disordered carbonlike structures. These polyelectrolyte/carbon nanotube composite capsules represent a novel light-addressable type of microcontainers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78050/1/3136_ftp.pd