Synthesis and properties of amphiphilic star polysulfides

We here present the synthesis and characterisation of linear and star-shaped amphiphilic block copolymers based on hydrophobic polysulfides (poly(propylene sulfide), PPS) and hydrophilic polyethers (poly(ethylene glycol), PEG). We also discuss the proof of the principle of their responsiveness to oxidising conditions. In a water environment, these polymers aggregate in the form of sub-micron carriers that, due to the sensitivity to oxidation reactions typical of PPS, can be used for responsive drug delivery. In this first study we have focused on the study of large aggregates, which do not apparently show dramatic differences in behaviour when polymer chains with different degrees of branching are studied.     

Synthesis of aromatic polysulfides on the basis of sulfur and naphthalene

Specific features of sulfur polycondensation with naphthalene in the presence of AlCl₃ and the influence exerted by synthesis conditions on the structure and properties of aromatic polysulfides being formed were studied. It was shown that the soluble polynaphthylene sulfides markedly surpass linear poly(1,4-phenylene sulfide) in thermal-oxidative stability. It was found that the predominance of the dehydropolycondensation of naphthalene to give a polynaphthylene structure cross-linked by sulfur over the polysulfurization of naphthalene and incorporation of sulfur into a linear chain. A high stability was demonstrated of polynaphthylene structures formed via dehydropolycondensation of naphthalene under the action of AlCl₃, followed by sulfurization of polynaphthylene with elementary sulfur into lateral chains.     

Synthesis and properties of aromatic polyamides containing the cyclohexane structure

1,1-Bis[4-(4-carboxyphenoxy)phenyl]cyclohexane (III) and 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane (V) were prepared in two main steps starting from the aromatic nucleophilic substitution of p-fluorobenzonitrile and p-chloronitrobenzene, respectively, with 1,1-bis(4-hydroxyphenyl)cyclohexane in the presence of potassium carbonate in N,N-dimethylformamide (DMF). Using triphenyl phosphite and pyridine as condensing agents, two series of polyamides with cyclohexylidene cardo groups were directly polycondensated from dicarboxylic acid III with various aromatic diamines or from diamine V with various aromatic dicarboxylic acids in an N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride. The polyamides exhibited inherent viscosities in the range of 0.45 to 1.78 dL/g. Almost all of the polymers were readily soluble in polar aprotic solvents such as NMP and N,N-dimethylacetamide (DMAc) and could afford transparent, flexible, and tough films by solution casting. The glass transition temperatures (T_g) of these aromatic polyamides were in the range of 180–243°C by DSC, and the 10% weight loss temperatures in nitrogen and air were all above 450°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3575–3583, 1999     

Synthesis,characterization, and properties of novel aromatic bispropenyl ethers

Aromatic bispropenyl ethers are a new class of highly reactive thermosetting monomers that have been prepared and characterized. Two synthetic routes to their preparation have been developed. The first of these involves the base-catalyzed isomerization of bisallyl ether precursors that gives predominantly the Z bispropenyl ether isomers. The second method employs tris(triphenylphosphine)ruthenium(II) dichloride as an isomerization catalyst and produces predominantly the E isomers. Using these methods, a number of bispropenyl ether monomers containing different aromatic groups have been synthesized. The cationic polymerization of these novel monomers to give crosslinked network polymers using diaryliodonium salts as photo and thermal initiators has been studied.     

Novel synthesis of aromatic polysulfides from S,S′-bis(trimethylsilyl)-substituted aromatic dithiols and activated aromatic dihalides

A new method for the synthesis of aromatic polysulfides has been developed by the polycondensation of S,S′-bis(trimethylsilyl)-substituted aromatic dithiols with activated aromatic dihalides. The solution polycondensation of three S-silylated aromatic dithiols with bis(4-chloro-3-nitrophenyl) sulfone afforded readily aromatic polysulfides having inherent viscosities of 0.7 dL/g, and the polymerization with bis(4-fluorophenyl) sulfone gave the polymers with viscosity values of 0.3 dL/g. The silylation method was compared advantageously with a conventional route using parent dithiols and activated aromatic dihalides.     

Synthesis,structure, and properties of N-quinoxalylformazans

The first representatives of the previously unknown N-quinoxalylformazans were synthesized. Their chemical properties were investigated, and their structure and chromaticity are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1705–1707, December, 1973.     

Synthesis and properties of aromatic block copolyimides

Anhydride terminated polyamic acid prepolymer was prepared from pyromellitic dianhydride and a diamine (para-phenylene diamine/benzidine) in dimethyl formamide. The prepolymer was reacted with the other diamine to obtain (A_nB)_m block copolymic acid. The polyamic acid was converted to the polyimide by thermal cyclodehydration. The properties of block copolyimides were compared with those of random copolyimides prepared by conventional routes.     

Synthesis and properties of alkylene-linked aromatic polyimides

Alkylene-linked aromatic polyimides were prepared from a family of new dianhydride monomers and aromatic diamines. The dianhydrides were synthesized by Friedel-Crafts catalysis of the condensation of ditertiary alcohols with o-xylene, subsequent oxidation of the aryl methyl groups to carboxy, and finally, dehydration of the ortho-carboxy substituents to anhydride groups. Alkylene-linked aromatic polyimides, with up to 8 methylene groups in the polymer chain, are stable to 400°C in air and can be extruded or compression-molded at 300°C. In addition, these polymers are soluble in solvents within the solubility parameter range of 10.4 ± 1.2.     

Synthesis and properties of semiconducting aromatic polyquinonediimines

A new class of poly-conjugated polymers has been obtained by condensation of anthraquinones with aromatic diamines in polyphosphoric acid. The polymers are black, intractable powders. Toward obtaining tractable materials, the effect of monomer structure on polymer tractability has been studied. Copolymerizations were also carried out to “soften” these materials. Electrical conductivities in the semiconducting range, 10^?4- 10^?8 (ohm cm)^?1 were observed. Doping with iodine showed small increases.     

Syntheses and properties of polysulfides containing spiroorthocarbonate moiety

Polysulfides (P_I and P_II) having spiroorthocarbonate moiety in the main chain were synthesized by the polyaddition of unsaturated spiroorthocarbonate ( 1 or 2 ) and dithiols in excellent yields. It is confirmed by DSC and x-ray measurement that P_II is the crystalline polymer. P_I and P_II were treated with a cationic catalyst such as BF₃ · OEt₂ and BzS⁺SbF to afford the crosslinked polymer and to partially undertake the main chain scission. Further, it was also found in the reaction of P_I and P_II with adipoyl chloride as the crosslinking reagent that P_I underwent cleavage of the main chain, but P_II mainly gave crosslinked polymers.     

Linear aliphatic polysulfides: Synthesis and characterization

Binary condensation copolymers of 1,2-ethane dithiol and 1,3-propane dibromide, 1,4-butane dibromide, and 1,6-hexane dibromide were prepared. Yields ranged from 55 to 89% with molecular weights of 1–2 × 10⁴ Daltons. The polymers were synthesized via an S_N2 process with and without the presence of water. The polymers were characterized by DSC, viscosity, FT-IR, and ¹H-and ¹³C-NMR spectra.     

芳基取代咪唑衍生物的合成及其紫外、荧光性质研究

设计合成了两种新颖的三芳基咪唑类化合物5和6,研究了其反应机理,优化了环合加成反应的工艺条件,化合物经FT-IR、HMR和MS进行结构表征。研究了两个化合物在不同溶剂中的紫外与荧光光谱,发现官能苄基的引入,会使吸收峰和发射峰均有不同程度的蓝移,这些光谱性质为今后研究其双光子吸收、双光子荧光和非线性光学性质奠定了实验基础。     

Synthesis,structure, and properties of LaSrCuGaO5

The new brownmillerite-related compound, LaSrCuGaO₅, has been synthesized and characterized. It crystallizes in the orthorhombic non-centrosymmetric space group Ima2. The unit cell dimensions are a = 16.383(1) Å, b = 5.5293(7) Å, c = 5.3275(6) Å. The structure is related to perovskite but contains ordered oxygen vacancies within the two-dimensional gallium oxygen layers resulting in tetrahedral coordination of the gallium cations. Other important structural features include buckled copper-oxygen planes, and disorder of the lanthanum and strontium cations over the A-site. Accurate lattice constant measurements reveal an a-axis expansion of 0.17 Å when doped with strontium La_1–xSr_1+xCuGaO₅ (x_max = 0.13). Magnetic susceptibility measurements demonstrate that the compound remains paramagnetic to 4 K.     

Synthesis,physical properties,and structure of TIPS-difuranoacenes

The synthesis, physical properties, and structure of triisopropylsilylethynyltetracenodifuran (2) and pentacenodifuran (3) derivatives were reported. There showed high stability in solution in the dark, yet decomposed under light. Single crystal of pentacenodifuran was analyzed by X-ray diffraction analysis, and showed one dimensional packing array along the c-axis. The molecules were stacked with a 3.30 Å interlayer distance. The crystals exhibited a high thermal stability under an ambient condition.     

Synthesis,structure, and properties of 1,3,5-triarylpyridazines

Treatment of γ-bromodypnone with arylhydrazines gives differently structured products, i.e. γ-bromo-dypnone hydrazones, 1-aryl-3,5-diphenyl-1,4-dihydropyridazines, 1-aryl-3,5-diphenyl-1,6-dihydro-pyridazines, and aromatic 1,3,5-triarylpyridazinium salts. We have studied the pattern of formation of all of the products and their properties. Heating an alcohol solution of 1,3,5-triphenyl-1,4-dihydro-pyridazine gives N,2,4-triphenyl-1H-pyrrole-1-amine or to a 1,3,5-triphenylpyridazinium salt dependent upon the acidity of the medium. The product of addition of HBr to the 1,6-dihydropyridazine system is 5-bromo-1-(4-nitrophenyl)-3,5-diphenyl-1,4,5,6-tetrahydropyridazine.     

Synthesis, structure, and properties of allylamino glycosides

Glycosylation of allylamine with D-glucose, D-galactose, and D-mannose in dry primary aliphatic alcohols was studied. The structures of the resulting N-allyl glycosylamines were established, and their reactivities were studied. It was found that N-allyl glycosylamines tend to structural isomerization involving a change in ring size and do not tend to radical polymerization in the presence of azo initiators.     

Synthesis, structure, and properties of azatriangulenlenium salts

A general synthetic route to novel nitrogen-bridged heterocyclic carbenium ions of the acridinium and triangulenium type has been developed and investigated. The synthetic method is based on nucleophilic aromatic substitution (SNAr) on the tris(2,6-dimethoxyphenyl)carbenium ion (1) with primary amines and, by virtue of its stepwise and irreversible nature, provides a powerful tool for the preparation of a wide variety of new heterocyclic carbenium salts. Several derivatives of the three new oxygen- and/or nitrogen-bridged triangulenium salts, azadioxa- (6), diazaoxa- (7), and triazatriangulenium (4), have been synthesized and their physicochemical properties have been investigated. Crystal structures for compounds 2 b-PF6, 2 d-PF6, 4b-BF4, 4c-BF4, 6e-BF4, and 8 are reported. The different packing modes found for the triazatriagulenium salts are discussed in relation to the electrostatic and space-filling requirements of the ions. The stabilities of the cations 6a, 7b, and 4a, as expressed by their pKR+ values, have been determined in strongly basic nonaqueous solution by use of the C_ acidity function; the values obtained were 14.5, 19.4, and 23.7, respectively. This study further implied that the C_ scale in its present form is unsuitable for the precise determination of pKR+ values beyond 22.     

Synthesis,structure and properties of fluorinated graphite

Fluorine-graphite intercalation compounds, C₂F to C₁₆F were synthesized by various methods. C-F bonds range from ionic to semi-covalent. These properties of C-F bonding give to fluorinated graphite metallic conductivity, higher hydrophilicity than graphite and high reduction potential. The c-axis and in-plane structures are governed by C-F bonding, fluorine intercalation rate and host graphites.