Journal of Materials Chemistry Blog

The thermal conductivities of blend-PI films containing ZnO nanoparticles have been investigated by researchers from Tokyo Institute of Technology for future electric and electronic applications.

The blend films obtained were composed of sulfur- and fluorine- containing PIs and exhibited distinct microphase-separated structures with a vertical double percolation morphology. These films had two principle advantages over conventional homo-PI systems. The smaller ZnO content in the blend-PI films conferred a larger thermal conductivity. Additionally, the thermal conductivity was larger in pristine (without ZnO nanoparticles) blend-PI films than homo-PI films. A higher thermal conductivity is advantageous for application in polymer dielectric materials, as it allows for better flexibility, light weight and higher electric insulation properties.

Interested to know more? Why not read the full article for free: D. Yorifuji and S. Ando, J. Mater. Chem., 2011, 21, 4402.

Researchers from Georgia Institute of Technology and University of Washington have synthesised dithienopyrrole–quinoxaline/pyridopyrazine donor–acceptor polymers by Stille coupling reactions.

It was found that the pyridopyrazine moiety is a stronger acceptor than quinoxaline and that the extended benzophenazine and dibenzopyridoquinoxaline species are stronger acceptors than quinoxaline and pyridopyrazine, respectively. When used in field effect transistors, average hole mobilities of up to ca 3.0 × 10^–4 cm² V^–1 s^–1 were obtained. Bulk heterojunction photovoltaic devices made from blends of the benzo[a,c]phenazine-based polymer gave average power conversion efficiencies of 1.4%.

Interested to know more? Why not read the full article for free: X. Zhang, J. W. Shim, S. P. Tiwari, Q. Zhang, J. E. Norton, P.-T. Wu, S. Barlow, S. A. Jenekhe, B. Kippelen, J.-L. Brédas and S. R. Marder, J. Mater. Chem., 2011, DOI: 10.1039/c0jm04290k (Advance Article)

Researchers from Chinese Academy of Sciences have prepared mesoporous hollow TiO₂ microspheres via a facile solvothermal method using glycine as a multifunctional smart template.

The glycine serves as a sacrificial template, complexing agent and water supplier in the TiO₂ microsphere synthesis and the cavity volume can be easily controlled by varying the mass of crude glycine used. Eu-doped TiO₂ hollow spheres have been made by this method and they exhibit stronger photoluminescence – due to their unique microstructures – compared to conventional, hydrothermal samples.

Interested to know more? Why not read the full article for free:  S. Ding, F. Huang, X. Mou, J. Wu and X. Lü, J. Mater. Chem., 2011, DOI: 10.1039/c0jm03628e (Advance Article)

Researchers from University of Idaho have synthesized and characterized 4-(trifluoromethyl and pentafluorosulfanyl)-substituted mono- and poly-1,2,3-triazole compounds.

These triazoles can be obtained in moderate to good yield from Cu(I) catalyzed 1,3-dipolar cycloaddition reaction of various azides with trifluoromethyl- and pentafluorosulfanyl-substituted acetylenes. The fluorinated triazene-(1,2,3-triazole) compounds exhibit the best detonation properties – comparable to that of TNT – and all bar one of them have high thermal stability (>270 °C) and are insensitive to impact.

Interested to know more? Why not read the full article for free: S. Garg and J. M. Shreeve, J. Mater. Chem., 2011, DOI: 10.1039/c0jm04229c (Advance Article)

Collagen-templated sol–gel fabrication, microstructure, in vitro apatite deposition, and osteoblastic cell MC3T3-E1 compatibility of novel silica nanotube compacts. Ca-containing silica nanotube compacts that could help bone regeneration have been created by a team from National Institute for Materials Science, Japan, and Okayama University, Japan. The compacts supported the attachment and proliferation of cells when soaked in the Kokubo’s simulated body fluid. The presence of Ca(II) promoted proliferation and differentiation, and led to formation of apatite and collagen fibrils. The team claims compacts could have a potential application for bone generation. J. Mater. Chem., 2011, DOI:10.1039/C0JM03823G (Advance Article)

Ultrabroad near-infrared photoluminescence from Bi5(AlCl4)3 crystal. A team from Japan has reported the first demonstration of a photoluminescence Bi5(AlCl4)3 crystal containing homonuclear polycation of Bi53+. This crystal, synthesized by an environmental friendly room-temperature method, displays extremely broad near-infrared photoluminescence. The team behind the research claim that this could help the design of other photonic materials containing a wide array of p-block elements. J. Mater. Chem., 2011, DOI:10.1039/C1JM10164A (Advance Article)

Manganite perovskite nanoparticles for self-controlled magnetic fluid hyperthermia: about the suitability of an aqueous combustion synthesis route. A team from France and the Czech Republic have developed a smart reproducible procedure for the preparation of well-separated core@shell perovskite nanoparticles. The nanoparticles were synthesized through an aqueous combustion process to take advantage of exothermic, fast and self-sustaining chemical reactions between metal nitrates and glycine as a suitable organic reducing agent. Fast calcination enhanced crystallinity of the nanoparticles and subsequent milling step was performed to favour their desaggregation before being coated with a 5 nm thick silica shell. J. Mater. Chem., 2011, DOI:10.1039/C0JM03963B (Advance Article)

Environmental effects on mechanochemical activation of spiropyran in linear PMMA. A colour changing spiropyran mechanophore was incorporated into linear poly(methyl methacrylate) by a team from University of Illinois at Urbana-Champaign, USA, and Beckman Institute for Advanced Science and Technology, USA. This system demonstrates mechanically induced chemical activation, which is strongly dependent on polymer mobility and can be controlled either thermally or using a plasticizing solvent. Activation occurred during a temperature window (90–105 °C), a characteristic which the team speculate could be found in other similar mechanochemical systems. J. Mater. Chem., 2011, DOI:10.1039/C0JM03967E (Advance Article)

SnO2 hollow structures and TiO2 nanosheets for lithium-ion batteries. Lithium-ion batteries are established as an important energy storage platform for portable electronics; however, there are constant and growing demands for better performance, improved safety, and enhanced reliability. A variety of nanomaterials has emerged as promising electrode materials for lithium-ion batteries. In this Feature Article, Jun Song Chen, Lynden A. Archer and Xiong Wen (David) Lou discuss two nanomaterials systems which show particular promise as anode materials for lithium-ion batteries: tin dioxide (SnO2) hollow spheres and anatase titanium dioxide (TiO2) nanosheets (NSs). J. Mater. Chem., 2011, DOI:10.1039/C0JM04163G (Advance Article)

PEDOT:PSS films with significantly enhanced conductivities induced by preferential solvation with cosolvents and their application in polymer photovoltaic cells. A team from the National University of Singapore have significantly enhanced the conductivity of a PEDOT:PSS film by a treatment with cosolvents. The cosolvent treatment improved the conductivity from 0.2 S cm−1 to more than 100 S cm−1. The team attribute the increase in conductivity to the preferential solvations of the PEDOT and PSS chains with the cosolvents, which induce the phase separation of PSSH chains from the PEDOT:PSS film, the aggregation of the PSSH segments in the PEDOT:PSS film, and the conformational changes of the PEDOT chains. The films created by this process are quite smooth and have high work functions. The team claim that the films are suitable to replace ITO as the transparent electrode of optoelectronic devices. J. Mater. Chem., 2011, DOI:10.1039/C0JM04177G (Advance Article)

Hierarchical ZnO microarchitectures assembled by ultrathin nanosheets: hydrothermal synthesis and enhanced photocatalytic activity. A simple and economical route to fabricate three-dimensional hierarchical ZnO microarchitectures has been developed by a team of Chinese scientists. The ZnO is assembled into a flowerlike morphology by many interleaving nanosheets which have ultrathin thickness of about 5 nm. The ZnO ‘flowers’ have high surface-to-volume ratio and a large population of unconventional (0001) surface planes. The team behind the research claim that this type of hierarchical ZnO microarchitectures display a strong structure-induced enhancement of photocatalytic performance and show a significantly improved photocatalytic activity over other monomorphological ZnO, such as ZnO nanoparticles, nanorods, and nanosheets. (J. Mater. Chem., 2011, Advance Article DOI:10.1039/C0JM03390A)

Photo-induced molecular alignment of trisazobenzene derivatives. Small-molecular trisazobenzene derivatives with a latent liquid-crystalline phase undergo a molecular realignment when exposed to linearly polarized visible light. These structures are unusually stable compared to structures based on other small-molecular organic compounds say the team behind the research. This phenomenon combines relatively short holographic writing times with small molecules in the fabrication of stable volume gratings. (J. Mater. Chem., 2011, Advance Article DOI:10.1039/C0JM03477K)

Restructuring of exponentially growing polyelectrolyte multilayer films induced by salt concentration variations after film deposition. In this hot paper a team of scientists based in France investigate films that experience changes in osmotic pressure through ionic strength changes of the contacting solution. The applied stresses lead often to the formation of holes. The team say that two types of holes are found: spherical holes formed by a direct increase or decrease of the ionic strength and non-spherical holes resembling cracks which appear after an increase followed by a decrease sequence of the ionic strength. (J. Mater. Chem., 2011, Advance Article DOI:10.1039/C0JM03457F)

Read all the articles for free until the 22nd March.

New hybrid core–shell star-like architectures made of poly(n-butyl acrylate) grown from well-defined titanium oxo-clusters. This paper reports for the first time the design of a hybrid star-like architecture by post-modification of a titanium oxo-cluster with polymer chains using two different strategies. The two routes are referred to as “grafting onto” and “grafting from”. The team behind this research say it demonstrates that titanium oxo-clusters are versatile nanobricks for the preparation of well-defined architectures such as star shaped hybrids. (J. Mater. Chem., 2011, DOI:10.1039/C0JM04047A Advance Article)

Photochemical stability of π-conjugated polymers for polymer solar cells: a rule of thumb. This hot paper reports a comparative photochemical stability study of a wide range of π-conjugated polymers relevant to polymer solar cells. The behaviour of each material has been investigated under simulated sunlight and ambient atmosphere. Based on this data the team from the Technical University of Denmark propose general rules for polymer structure–stability relationships. (J. Mater. Chem., 2011, DOI:10.1039/C0JM03105D Advance Article)

Controlled synthesis and optical characterization of multifunctional ordered Y2O3 : Er3+ porous pyramid arrays. Y2O3 is an important industrial compound widely used in antireflective coatings and transparent ceramics. In this hot paper, Xiangfu Wang, Xiaohong Yan and Caixia Kan synthesise Y2O3 : Er3+ porous pyramid arrays with a honeycomb micropore structure and investigate their optical characteristics. The team from China say that  Y2O3 : 5%Er3+, 5%Li+ porous pyramid arrays could be used to decrease the reflection and transmission loss for C–Si solar cells.  (J. Mater. Chem., 2011, DOI:10.1039/C0JM03761C Advance Article)

Interested to know more?  Read these articles for free until 18th March.

Piezochromic luminescence of amide and ester derivatives of tetraphenylpyrene—role of amide hydrogen bonds in sensitive piezochromic response.  Amide-substituted tetraphenylpyrene show sensitive and reversible piezochromic response to applied pressure. The team behind this research say this arises from the hydrogen bond-directed columnar assemblies. Piezochromic luminescent materials could find use as optical recording and strain- or pressure-sensing materials. (J. Mater. Chem., 2011, DOI:10.1039/C0JM03950K, Advanced Article)

One dimensional Si/Sn – based nanowires and nanotubes for lithium-ion energy storage materials. One dimensional Si/Sn nanowires and nanotubes have great potential to achieve high energy density and long cycle life for next generation advanced energy storage applications. In this Hot Feature Article, Yi Cui, Jaephil Cho and coworkers discuss recent progress and future challenges for Si/Ge/Sn based nanowires and nanotubes as high capacity anode materials.  (J. Mater. Chem., 2011, Advance Article DOI:10.1039/C0JM03842C)

Nonclustered magnetite nanoparticle encapsulated biodegradable polymeric micelles with enhanced properties for in vivo tumor imaging. Folate-encoded and small-sized polymeric micelles loaded with nonclustered SPIO show high MRI sensitivity and targeted delivery for effective detection of human hepatoma say a team of scientists from China and the USA. (J. Mater. Chem., 2011, DOI:10.1039/C0JM03783D Advanced Article)

Read all the articles for free until 14th March.

Plasmon-resonant nanostars provide excellent contrast enhancement for photoacoustic tomography claim US scientists. The team behind the research, led by Lihong Wang at Washington University in St Louis, US, say that the high photoacoustic sensitivity of plasmon-resonant nanostars at near-infrared wavelengths enables the in vivo detection in rat sentinel lymph nodes and vessels. These materials could act as contrast agents for lymphangiography.

Read the Article for free until 11th March:

Chulhong Kim, Hyon-Min Song, Xin Cai, Junjie Yao, Alexander Wei and Lihong V. Wang, J. Mater. Chem., 2011, DOI:10.1039/C0JM04194G (Advance Article)