New thermo-crosslinking reactions of polymers containing pendant epoxide groups with various polyfunctional active esters

New thermo-crosslinking reactions of poly(glycidyl methacrylate), copolymers of glycidyl methacrylate with methyl methacrylate, styrene or ethyl acrlate with various active esters such as di[S-(2-benzothiazoly)] thioadipate (BTAD), di(S-phenyl) thioadipate (PTAD), di(4-nitrophenyl) adipate (NPAD), diphenyl adipate (PAD), and di(S-phenyl) thioisophthalate (PTIP), and other polyfunctional esters were carried out in the film state using various catalysts such as quarternary ammonium or phosphonium salts, tert amines, or the crown ether 18-crown-6 = potassium salts system. Addition reactions of pendant epoxide groups in the polymer with the active esters such as NPAD and PTAD proceeded selectively to give gel compounds without other side reactions. The rates of reaction with the thioesters such as BTAD and PTAD were relatively faster than those with the phenyl esters such as PAD and NPAD at 70°C. The rates of reactions with the esters having flexible segments such as PTAD were also faster than those with the esters having rigid skeletons such as PTIP. Furthermore, it was found that the rate of reaction was affected strongly by reaction temperature, catalyst concentration, length of alkyl chain in the catalyst, kind of counterion of quarternary ammonium salts as a catalyst, content of pendant epoxide groups in the polymer, and kind of copolymer unit in the polymer, respectively.     

System for coincidence measurements of the ions desorbed and projectiles scattered from noble gas solid surfaces by slow multiply charged ion impacts

We have developed a new experimental apparatus for performing coincidence measurements of the ions desorbed and projectiles scattered from the surfaces of noble gas solids by slow multiply charged ion impacts at grazing incidence angles. This simultaneously measures the desorbed ions' flight times and the scattered projectiles' charge states. We also conduct experiments on 6 keV Ar⁶⁺ impacts onto a solid Ne surface using the device.     

Metal oxides immobilized fabrics by radiation induced graft polymerization

Radiation induced graft polymerization is effective for adding a new functionality to various forms of existing polymers. Ion-exchange nonwoven fabrics by gamma radiation induced graft polymerization have been used as filters in air and liquid. However, these materials have no capability for removing non-ionic species, such as volatile organic compound and ozone. Manganese oxides immobilized fabrics were developed for removing ozone. In addition, these materials were capable of removing formaldehyde and arsenic. Fine particles of manganese oxides were observed on the fibers. New materials produced by radiation induced graft polymerization and metal immobilization were applicable for purification of contaminants in environment. Manufacturing process is applicable for immobilization of the other metal oxides.     

Synthesis of imidazole‐containing conjugated polymers bearing phenol unit as side group and excited state intramolecular proton transfer‐mediated fluorescence

Dibromobenzimidazole and dibromoimidazole bearing hydroxyl group‐protected phenol unit ( 1 and 2 ) were prepared and they showed an intramolecular hydrogen bonding between ether oxygen and amino proton of imidazole. The palladium‐catalyzed Suzuki coupling polymerization of 1 and 2 with benzene bis(boronic acid) derivatives gave soluble polymers ( 3 and 4 ), where the molecular weights were limited probably due to the coordination ability of imidazole to palladium metal. The phenol hydroxyl groups were subsequently deprotected using BBr₃ to obtain 3 ′ and 4 ′. From the ¹H NMR spectra, the complete conversion to the hydroxyl group and the formation of another type of intramolecular hydrogen bonding between hydroxyl proton and imine nitrogen were confirmed. In the UV and PL spectra of 3 ′ and 4 ′, the excited state intramolecular proton transfer (ESIPT) occurred to shift the emission spectra toward lower energy region compared to 3 and 4 . Especially, the PL spectrum of 3 ′ demonstrated large stokes shift (145 nm) in THF solution. The ESIPT‐mediated fluorescence was influenced by the addition of methanol and trifluoroacetic acid, which inhibited the formation of intramolecular hydrogen bonding. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4822–4829, 2009