A series of high-density branched polymers have been synthesized by the coupling reaction of poly(4-(3-(4-bromomethylphenyl)propyl)styrene with polymer anion comprised of two same or different polymer chains, prepared from polystyryllithium and either polystyrene or polyisoprene with 1,1-diphenylethylene chain-end functionalization. Under certain conditions, the reaction proceeded essentially quantitatively to afford the requisite extremely high-density branched polymers carrying two branch chains in each repeating unit and having M w values of up to 3 × 106. Furthermore, quite new graft-block copolymers with similar high-density branched architectures could also be successfully synthesized. The resulting polymers are well-defined in branched architecture and precisely controlled in chain lengths of both backbone and branch segments. It was however observed that the reaction efficiency was significantly affected by several variables such as degrees of polymerization of the backbone polymer and polymer anion and branched and chemical structures of the polymer anion. The structures of the resulting high-density branched polymers were investigated by intrinsic viscosity measurement. These polymers may possibly adopt starlike structures in toluene as evidenced by their g‘ values.

Three kinds of new substituted polystyrene derivatives functionalized with two or four benzyl bromide moieties in every monomer unit were successfully synthesized via living anionic polymerizations, functionalization reactions with the 1,1-diphenylalkyl anion prepared from 1,1-bis(3-tert-butyldimethylsilyloxymethylphenyl)ethylene and sec-BuLi, and transformation reactions with LiBr−(CH3)3SiCl. These polymers were precisely controlled in chain length and quantitatively functionalized with benzyl bromide moieties. The synthesis of well-defined densely branched polystyrenes and graft copolymers carrying two or more branches in all repeating units were attempted using the coupling reactions of such benzyl bromide-functionalized polystyrenes with living anionic polymers of styrene, isoprene, and tert-butyl methacrylate in THF at −40 °C. The coupling reaction was found to proceed quantitatively under appropriate conditions to afford densely branched polymers carrying two branches in each repeating unit. In contrast, the coupling reaction of the polystyrene functionalized with four benzyl bromide moieties with living anionic polymers of styrene was incomplete and only two polystyrene chains could be introduced in each repeating unit. The structures of the resulting branched polystyrenes were investigated by intrinsic viscosity measurement. These polymers may adopt starlike rather than rodlike structures in toluene as evidenced by their g‘ values.

No abstract

῍῍῍῍῍῍῍῍῍῍῍῍῍῍῍῍Cross-linked starch suspensions sheared at various shear stresses showed two types of flow behavior. One type indicates a behavior of increasing fluidity, which is observed in concentrated suspensions of weakly cross-linked starch. Although sheared granules are smaller than non-sheared granules, the increasing fluidity of cross-linked starch suspensions is explained by the rupture of fully swollen starch granules. As the swollen granules rupture, the flocculation network of the granules decreases, resulting in a decrease in the viscosity and an increase in the fluidity of starch suspensions. Another flow behavior is decreasing fluidity, which is observed in highly cross-linked starch. The decreasing fluidity of cross-linked starch suspensions results from the re-swelling of granules from the application of unheated shear stress. The re-swollen granules enlarge with strong flocculation, resulting in a decrease of fluidity. Hence, the disruption or the re-swelling of sheared granules explains the two types of fluidity observed in cross-linked starch suspensions. A combination of cross-linking level and starch concentration determines the fluidity type of gelatinized suspensions.(Received Nov. +, ,**0 ; Accepted Feb. ,2, ,**1)

This study examined the effects of drying methods on the generation of flavor compounds in Karebushi. First, in order to obtain the primary mold culture product, Eurotium repens (YM-1418) was sprayed on the surface of Hadakabushi and cultured for two weeks. The samples were then dried either under the sun or by a machine (dehydrator). Subsequently, the samples were cultured for another week to produce a secondary mold culture product. The flavor compounds of samples were analyzed using GC-MS. Forty major flavor compounds were identified, and among these compounds, hexanal, heptanal, and octanal were quantified. Results indicated that the different drying methods led to the generation of different flavor compounds, especially of aldehydes. Furthermore, in comparing the sun-drying and machine-drying methods, the former increased hexanal and heptanal, and the extent of these increases was proportional to the duration of sun-drying. We also identified that the production of these aldehydes increased when drying during spring and summer. Next, the increase of these aldehydes was clarified by the UV irradiation test. We revealed that the sun's UV rays were mainly responsible for the remarkable increase in hexanal and heptanal during the Karebushi manufacturing process.