Mikiharu Kamachi

ESR observation of propagating radical and estimation of propagation rate constant in the radical polymerization of vinyl chloride

Well-resolved electron spin resonance (ESR) spectra of propagating radicals in radical polymerizations of vinyl chloride have been detected under irradiation for the first time. Structure of propagating radicals of vinyl chloride was investigated on the basis of hyperfine splitting constants (hfcs) of the ESR spectrum. The spectrum was assisgned to a chain end propagating radical. The propagation rate constant (k p ) for the radical polymerization of vinyl chloride was also estimated by ESR spectroscopy. The value of k p for vinyl chloride was (5 400 ± 1 500) M -1 .s -1 at 25°C, which is in agreement within experimental error with one of those obtained by the rotating sector method.

ESR study on radical polymerization and its application to microemulsion systems

Well-resolved electron spin resonance (ESR) spectra of propagating radicals of vinyl and diene compounds were observed in a single scan by a conventional CW-ESR spectrometry without the aid of computer accumulation and the specially designed cavity and cells Although solvents which could be used for ESR measurements were restricted to nonpolar solvents, such as benzene, toluene, and hexane, new information on dynamic behavior and reactivity of the propagating radicals in the radical polymerization of vinyl and diene compounds were obtained. Thus, values of propagation rate constants (k p ) for vinyl and diene compounds were determined by an ESR method. Some of the k p values were in a fair agreement with those obtained by a pulsed laser polymerization (PLP) method. Furthermore, polymer chain effect on apparent k p was clearly observed in the radical polymerization of macromonomers and in the microemulsion polymerization. In ESR measurement on inclusion polymerization system, important information on the origin of the 9-line spectrum observed in the radical polymerization of methacrylate propagating radicals was obtained.

Initiator-free photo-emulsion polymerization of deuterated methyl methacrylate

Initiator-free Photo-emuslsion polymerization of deuterated methyl methacrylate (MMA-d8) was carried out at 0 °C by using polyoxyethylene nonyl phenylether sodium sulfate (LWZ, Kao Co). After 24 h UV irradiation, poly(MMA-d8) was obtained by 9% yield and the Pn was 4340 on the basis of the intrinsic viscosity in acetone. In the 1H-NMR spectrum of poly(MMA-d8), LWZ fragments were observed and were considered to be bound to the ends of poly(MMA-d8).

Supramolecular formation of porphyrins and antibodies

The supramolecular formation of tetracarboxyphenylporphyrin (TCPP) and anti-TCPP antibody was studied by a biosensor (BIAcore) and atomic force microscope (AFM). Results of BIAcore for the complexes of antibodies with TCPP suggested the supramolecular formation with the binding of two antibodies and a porphyrin molecule. AFM images of cyclic trimer, pentamer and linear oligomers constituted by antibodies and porphyrin dimers were obtained.