环Fp+vFp上互补对偶常循环码

本文研究了环F_p+vF_p上互补对偶（1-2v）-常循环码.利用环F_p+vF_p上（1-2v）-常循环码的分解式C=vC_1-v ⊕（1-v）C_v,得到了环F_p+vF_p上互补对偶（1-2v）-常循环码的生成多项式.然后借助从F_p+vF_p到F_p²的Gray映射,证明了环F_p+vF_p上互补对偶（1-2v）-常循环码的Gray像是F_p的互补对偶循环码.     

Cationic polymerizations of substituted 2-methylene-1,3-dioxocyclic acetals, 2-methylene-1,3-dithiolane and copolymerization of 2-methylene-1,3-dithiolane with 4-(t-butyl)-2-methylene-1,3-dioxolane1

Carbon black-supported sulfuric acid or BF₃·Et₂O-initiated polymerizations of 2-methylene-4,4,5,5-tetramethyl-1,3-dioxolane (1), 2-methylene-4-phenyl-1,3-dioxolane (2), and 2-methylene-4-isopropyl-5,5-dimethyl-1,3-dioxane (3) were performed. 1,2-Vinyl addition homopolymers of 1–3 were produced using carbon black-supported H₂SO₄ initiation at temperatures from 0°C to 60°C whereas both ring-opened and 1,2-vinyl structural units were present in the polymers using BF₃·Et₂O as an initiator. Cationic polymerizations of 2-methylene-1,3-dithiolane (4) and copolymerization of 4 with 2-methylene-4-(t-butyl)-1,3-dioxolane (5) were initiated with either carbon black-sulfuric acid or BF₃·Et₂O. Insoluble 1,2-vinyl addition homopolymers of 4 were obtained upon initiation with the supported acid or BF₃·Et₂O. A soluble copolymer of 2-methylene-1,3-dithiolane (4) and 4-(t-butyl)-2-methylene-1,3-dioxolane (5) was obtained upon BF₃·Et₂O initiation. This copolymer is composed of three structural units: a ring-opened dithioester unit, a 1,2-vinyl-polymerized 1,3-dithiolane unit, and a 1,2-vinyl polymerized 4-(t-butyl)-1,3-dioxolane unit. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2823–2840, 1999     

Copolymerization of carbon dioxide and propylene oxide using an aluminum porphyrin system and its components

The catalytic activities of tetraphenylporphinatoaluminum chloride (TPPAlCl) and its propylene oxide adduct (TPPAl(PO)₂Cl) were investigated in detail together with a quarternary salt Et₄NBr for the copolymerization of carbon dioxide and propylene oxide. In addition, for the components and starting raw materials of the catalyst systems, catalytic activities were examined for the copolymerization. The TPPAlCl catalyst delivered oligomers containing ether linkages to a large extent, regardless of its PO adduction. And cyclic propylene carbonate, as byproduct, was formed in a very small portion. Using the TPPAlCl coupled with Et₄NBr as a catalyst system, the formation of ether linkages was reduced significantly in the copolymerization; however, the obtained oligomer still contained ether linkages of 25.0 mol % in the backbone. On the other hand, the formation of cyclic carbonate was increased to 22.4 mol % relative to the oligomer product. The results indicate that the salt, which was coupled with the TPPAlCl catalyst, plays a key role in reducing the formation of ether linkage in the oligomer and, however, in enhancing the formation of cyclic carbonate. Similar results were obtained for the copolymerization catalyzed by the TPPAl(PO)₂Cl/Et₄NBr system. That is, the formation of ether linkages was not restricted further by the PO adduction of the TPPAlCl component in the catalyst system. Only oligomers with a relatively high molecular weight were produced. This indicates that the PO adduction of the TPPAlCl component contributes highly to the initiation and propagation step in the oligomerization, consequently leading to a relatively high molecular weight oligomer. In contrast, the Et₄NBr, as well as the Et₂AlCl, produced only cyclic carbonate in a very low yield. Furthermore, tetraphenylporphine exhibited no catalytic activity, regardless of using together with Et₄NBr. On the other hand, the Et₂AlCl coupled with Et₄NBr provided a low molecular weight oligomer having ether linkages of 92.3 mol % in addition to the cyclic carbonate. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3329–3336, 1999     

Electrical conductivity of heat treated polyacrylonitrile and its copper halide complexes

The electrical conductivity of polyacrylonitrile homopolymer and polymer complexes of acrylonitrile (PAN) with CuCl₂, CuBr₂, and Cul₂ was measured at different temperatures. It was found that the electrical conductivity increased with temperature. Cyclic voltammetry was used for measuring the shift of the reduction peaks upon heat treatment of the polymer complexes. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3057–3062, 1999     

Synthesis and characterization of a novel carbazole cyclic oligomer and main-chain polymer

The efficient synthesis of a novel cyclic carbazole tetramer and carbazole main-chain polymer via the Knoevenagel condensation has been developed. The carbazole cyclic tetramer could be obtained in a high yield by a one-stage Knoevenagel condensation of 3,6-diformyl-9-heptylcarbazole and 3,6-bis(cyanoacetoxymethyl)-9-heptylcarbazole in tetrahydrofuran (THF) without the use of the high-dilution principle. The corresponding carbazole main-chain polymer could also be obtained as a main product by a two-stage Knoevenagel polycondensation. Detailed structural characterization of this novel oligomer by spectroscopy and elemental analysis confirmed the cyclic structure. The corresponding main-chain polymer with large molecular weight was found to be amorphous by differential scanning calorimetry. Studies on the nonlinear optical and photorefractive properties of these materials are in progress. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2041–2047, 1997     

Polyarylenes on the Basis of Alkylpyrrole and Alkylcarbazole Derivatives and their Oligomeric Model Systems

The redox and spectroscopic properties of soluble poly- (9-decylcarbazole) derivatives and poly(1-decylpyrrole) were studied. The polymers were synthesized via the Yamamoto polycondensation method. Analyzing the electrochemical and optical properties of 3,6-linked poly(alkylcarbazole)s it is evident that the conjugation segment is the benzidine system and the overall properties of these polymers can be compared with meta linked poly(phenylene)s. In opposite, 2,7-linked poly(alkylcarbazole)s reveal an even longer conjugation segment comparable with para linked poly(phenylene)s. First observations in the case of poly(1-decylpyrrole) suggest a higher steric hinderance compared to poly- (1-methylpyrrole). Molecular modeling studies confirm this. © 1997 John Wiley & Sons, Ltd.     

BF3·OEt2-initiated polymerization of 2-methylene-1,3-dioxepanes

BF₃·OEt₂-initiated polymerizations of 2-methylene-1,3-dioxepane gave polymers composed of both ring-retained and ring-opened structures. The ring-opening content increased with an increase in polymerization temperature. Poly(4,7-dimethyl-2-methylene-1,3-dioxepane) propagated slower during BF₃·OEt₂-initiated polymerization and had a lower ring-opened content than poly(2-methylene-1,3-dioxepane). The type of acid initiator used also affected the amount of ring opening observed. Stronger acids gave less ring opening. Attempted BF₃·OEt₂-initiated copolymerizations of these seven-membered ring cyclic ketene acetals with isobutyl vinyl ether at room temperature resulted in formation of the two homopolymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 873–881, 1998     

Cyclic(arylene ether) oligomers containing the phenylphosphine oxide moiety

A series of cyclic(arylene ether) oligomers containing the phenylphosphine oxide moiety has been synthesized by reaction of bis(4-fluorophenyl)phenylphosphineoxide with dihydroxy compounds 1a–d as well as 1,2-dihydro-4-(4-hydroxyphenyl) (2H)phthalazin-1-one in DMF in the presence of anhydrous K₂CO₃ under high dilution conditions. These cyclic oligomers are amorphous and have high solubility in organic solvents. The MALDI-TOF-MS technique has been used as a powerful tool to analyze these cyclic systems. The cyclic(arylene ether) oligomers readily undergo anionic ring-opening polymerization in the melt at 350°C by using potassium 4,4′-biphenoxide as the initiator, affording linear, high molecular weight poly(arylene ether)s containing the phenylphosphine oxide moiety. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 519–526, 1998