Novel donor-acceptor-donor-type compounds were developed based on the electron-deficient dibenzo[a,c]phenazine (dbpz) skeleton, and their photoluminescence (PL) properties were investigated. Introduction of electron-donating π-conjugated side-arms at the 10,13-positions of dbpz yielded intramolecular charge transfer (ICT)-type chromophores showing remarkable fluorescent properties. When the electron-donating ability of the side-arm was varied, the emission color was tuned from yellowish green to deep red. Especially, 4-hexylthiophen-2-yl, 5-(9,9-dihexyl-9H-fluoren-2-yl)thiophen-2-yl and 5-(9-(2-ethylhexyl)-9H-carbazol-3-yl)thiophen-2-yl side-arms were effective to obtain red-emissive fluorophores. The developed dbpz derivatives exhibited remarkable positive fluorescent solvatochromism, indicating their strong ICT electronic structures. Using the dbpz derivative as an emitting dopant, organic light-emitting diodes were fabricated, and electroluminescence corresponding to PL of the emitting dopant was observed upon application of voltage.
Eleven novel bisazomethine dyes possessing a dibutylamino terminal group with diverse alkoxy substituents on the phenyl ring were prepared by a reaction of diaminomaleonitrile and aminobenzaldehydes. We observed that ten derivatives exhibited red-shifted fluorescence in a crystalline state with an improved quantum efficiency from that in a solution. They showed red to near-infrared fluorescence with a quantum efficiency in the range of 12 to 28%. X-ray crystal structure analysis was carried out for interpreting optical properties in a crystalline state. The solid-state fluorescence property of the derivatives with a long alkoxy side chain could be characterized by their structural feature, whereas no close correlation was found between the solid-state fluorescence property and structure feature in crystal structure in the derivatives with a short to middle alkoxy side chain.
To simplify miniemulsion polymerization procedure, temperature induced phase inversion phenomenon is utilized. Small polymer particles, whose average diameter is less than 40 nm, were obtained by radical polymerization at phase inversion temperature (PIT). Fluorescent pyrene was added before or after the polymerization. The polymer particles prepared by the polymerization at PIT contained more pyrene in the case pyrene was added before the polymerization than in the case pyrene was added after the polymerization. Polymerization of vinyl monomer with functional water-insoluble materials, water, nonionic surfactant and initiator at PIT is suitable for preparation of small polymer particles containing the functional materials.
Polymer particles have been attracting much attention as a potential dispersed material available for paints, adhesives, electric devices, and in vitro diagnostics. Polymer particles have been prepared by several techniques such as emulsion polymerization considering both the technical advantages and economic aspects. With the progress of heterophase radical polymerizations, various types of core-shell polymer particles with a controlled structure and surface functional groups have been developed. Recently, surface functionalization of polymer particles through living radical polymerization has been energetically investigated. This article reviews the recent advances and developments in graft polymerization by atom transfer radical polymerization (ATRP) from the particle surface. In addition, the preparation of polymer particles by polymerization of oil-in-water (O/W) emulsion monomer droplets obtained through the phase inversion temperature (PIT) emulsification technique is also introduced.
In the pulp & paper field, many surfactants are being used with various functions such as de-resining agents, felt cleaners, pitch controlling agents, de-inking agents, defoamers, dispersants for pigments, bulking promoters and so on. These chemicals are helping to produce pulps and papers by using their basic function as a surfactant.
In this article, the de-inking agent and bulking promoter are presented. The de-inking agent is used when waste papers are recycled. The bulking promoter is used when thick and soft papers are produced.
More than 10 years have passed since safety concerns of nanomaterials were first pointed out. It is still not clear what kind of regulatory framework is suitable for engineered nanomaterials. The European Union established a regulatory definition, and requires manufacturers to label “nano” and conduct a specific risk assessment if applicable. The United States applies current regulatory requirements to nanomaterials on a case-by-case basis based on whether there are novel functions stemming from their nanoscale size, without establishing regulatory definitions. Japan has made effort to build an international consensus, despite being inactive in domestic regulatory development. In this paper, I set the scene of the legislative approach for nanomaterials in the first section. The second section describes administrative actions in Japan from 2008. The third and fourth sections summarize regulatory development in the United States and European Union. Then the challenges are described in the final section.