Four vinyl sulfonate ester derivatives, neopentyl ethenesulfonate (NES), 1-butyl ethenesulfonate (BES), isopropyl ethenesulfonate (IPES), and phenyl ethenesulfonate (PES), were polymerized by conventional radical polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization. Three xanthate-type chain transfer agents (CTAs), a dithiocarbamate-type CTA, and a dithioester-type CTA were compared for these RAFT polymerizations. Among various CTAs, O-ethyl-S-(1-methoxycarbonyl) ethyldithiocarbonate was the most efficient to obtain poly(NES) and poly(BES) having low polydispersities. The effects of several parameters, such as temperature and CTA to initiator molar ratio, were examined in order to determine the conditions, leading to optimal control of the polymerization. With the xanthate-type CTA under suitable conditions, reasonable control of the polymerization of NES was confirmed by the formation of the relatively low polydispersity products, linear increase in the molecular weight with the conversion, and feasibility in the control of the molecular weight based on the ratio of monomer consumed to the amount of CTA used. The polymerization behavior of BES was comparable to that of NES. Deprotection of the neopentyl group of the poly(NES) proceeded smoothly to give water-soluble poly(lithium vinyl sulfonate). Synthesis of the well-defined block copolymer involving the poly(lithium vinyl sulfonate) segment was conducted by RAFT polymerization of NES using poly(N-vinylcarbazole) macro-CTA, followed by deprotection.
The space group in the orthorhombic phase of La2CuO4-δ was confirmed to be Cmca for both as grown and deoxygenated crystals by using conventional and convergent beam electron diffraction together with high resolution neutron powder diffraction methods. The Rietveld refinements of neutron powder diffraction data determined the structural parameters. Slight differences in lattice constants, positional parameters and occupation factor for oxygen atoms were found between the two crystals.
Incident energy dependence of isotopie yield distributions of target-like and fission-like products was studied in the heavy-ion reaction of 14 N on "Ni by the radiochemical method. Cobalt and scandium isotopes were chosen as samples of the former and the latter products, respectively, and the energy range covered was 70 to 122 MeV. Formation cross-sections of cobalt and scandium isotopes were found to increase with increasing energy, and their isotopie yield distributions could be fitted by a Gaussian function for the energy region greater than 70 MeV. The most probable N/Z ratio for cobalt isotopes fell between the Ν¡Z ratio of the compound nucleus and the target nucleus, but it was smaller than that of the compound nucleus for scandium isotopes. The formation cross-sections of cobalt isotopes showed the Qgg dependence, except for those of 60 Co. The nuclear temperature deduced from Q gg dependence was independent of the incident energy. Both the excitation functions and the recoil study of scandium isotopes support the proposition that they are produced by fission of a fully equilibrated system.
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