Synthesis and properties of polyampholytes prepared in microemulsions

A series of polyampholytes of sodium 2-acrylamido-2-methylpropanesulfonate (NaAMPS) and 2-(methacryloyloxy)ethyltrimethylammonium chloride (MADQUAT) has been synthesized by polymerization in microemulsions. The reaction products are stable inverse latexes consisting of high molecular weight copolymers entrapped in water droplets of small size (d % 80 nm) and dispersed in an isoparaffinic oil. The optimization of the formulation was by a selection procedure based on the hydrophile-lipophile balance of the emulsifiers and solubility parameters of the different components. Both ionomers play an important role in the formulation owing to their amphiphilic and electrolyte characters. Reactivity parameter studies yield r_A and r_M values of 0.81 and 1.97 for NaAMPS and MADQUAT, respectively. The properties of polyampholytes in pure water and in salt solutions were investigated by turbidimetry and viscometry experiments. The results are compared with the recently developed theory of Higgs and Joanny (J. Chem. Phys. 94, 1543 (1991)).     

Aqueous solution properties of polyampholytes: Effect of the net charge distribution

Viscometric and light scattering studies have been performed on aqueous solutions of polyampholyte terpolymers based on sodium-2-acrylamido-2-methylpropanesulfonate (Na-AMPS), 2-(methacryloyloxy)-ethyltrimethylammonium chloride (MADQUAT), and acrylamide (AM), prepared by an inverse microemulsion polymerization technique. The distribution of net charges among the chains was varied by adjusting the initial monomer composition and the degree of conversion. The effect of this distribution on the solubility of the samples and on the chain conformation was studied. It was found that samples with a narrow distribution of net charges were soluble in pure water even if the average net charge is small. Addition of salt induces a transition from an extended conformation to a more compact one, in qualitative agreement with theoretical predictions. A practically alternated NaAMPS-MADQUAT copolymer prepared by polymerization in homogeneous solution and with a small average net charge shows a behavior quite similar to that of the terpolymers. © 1996 John Wiley & Sons, Inc.     

Synthesis,characterization and properties of novel cellulose derivatives containing phosphorus: cellulose diphenyl phosphate and its mixed esters

Using ionic liquid 1-allyl-3-methylimidazolium chloride as reaction medium, a series of novel cellulose esters containing phosphorus including cellulose diphenyl phosphate (C-Dp) and cellulose acetate (CA)–diphenyl phosphate mixed esters was synthesized homogeneously. The degree of substitution was well controlled by altering reaction conditions, such as the molar ratio of the acylating reagents/anhydroglucose unit and reaction time. The structure and thermal properties of cellulose esters were characterized by FTIR, NMR, wide-angle X-ray powder diffraction and differential scanning calorimetry. All the products possessed excellent solubility in some common organic solvents, and transparent films of cellulose esters were obtained by solution casting. In contrast to C-Dp, CA–diphenyl phosphate mixed esters showed clear glass transitions. More interestingly, these cellulose mixed esters exhibited thermoplastic behavior and could be processed by traditional melt processing methods.     

Synthesis, structure, and magnetic properties of two novel lanthanide-organic frameworks

Two novel metal-organic frameworks, {[Eu(phen)(NDA)1.5(H2O)]}n ((1); NDA = 2,6-naphthalenedicarboxylate ions, phen = 1,10-phenanthroline) and {[Gd(phen)(NDA)1.5]·0.5H2NDA}n (2), have been synthesized under hydrothermal conditions. The structure analyses of 1 and 2 reveal that the two compounds belong to the triclinic system with space group P-1. Compound 1 features a 2D lattice structure while compound 2 displays a novel 3D architecture. The two frameworks were further characterized by elemental analyses, l...     

Synthesis,structure and properties of three novel transition-metal-containing tantalum-phosphate clusters

Peroxide ligation of aqueous metal–oxo clusters provides rich speciation and structural diversity. Here, three novel transition-metal derivatives of polyoxometalate anions, [Ni₂(H₂O)₁₀{P₄Ta₆(O₂)₆O₂₄}]^6– (1a), [Zn(H₂O)₄{P₄Ta₆(O₂)₆O₂₄}]^8– (2a) and [Cd(H₂O)₄{P₄Ta₆(O₂)₆O₂₄}]^8– (3a), have been successfully synthesized by adopting a one-pot reaction strategy. All of these hexatantalates are built from a new-type phosphorus-incorporated hexatantalates. We investigated the solution behaviors, and the peak assignments of the MS spectra indicated some degree of stability of them in water. Furthermore, the proton-conducting ability of compound 1a was also explored and it has shown well conductivity at high relative humidities, with conductivity achieved 1.22 × 10^–3 S/cm (85 °C, 90%RH).     

Polyurethanes based on asymmetric dimethylhydrazine: Synthesis, structure, and properties

New polyurethanes have been synthesized from asymmetric dimethylhydrazine at a nonstoichiometric ratio of the starting reagents. With the use of various methods, the number-average molecular mass of the polymers has been estimated and conclusions concerning their possible structure have been made.     

基于Cz-DPP不对称D-A结构新型有机小分子光伏材料的合成与性质

本文设计合成了一系列以咔唑(CZ)和吡咯并吡咯二酮(DPP)为基本结构单元的D-A结构的新型小分子材料,并对其进行了一系列的性能表征.合成的材料以咔唑作为给电子单元,吡咯并吡咯二酮作为吸电子单元,采用三键作为π桥,并引入4-氟苯基、4-氰基苯基和4-甲氧基苯基作为末端取代基团对材料进行修饰.其中材料CZBTDPPF和CZBTDPPO因分别具有1.85和1.79 eV的较窄带隙而分别获得了相对较高的的光电转化效率(1.97%和1.91%).由此可见,引入4-氟苯基和4-甲氧基苯基作为末端取代基团对于延长材料共轭结构、拓宽材料吸收从而实现材料光伏性能的提升具有重要的作用.     

Composite hydrogels based on polyacrylamide and cellulose: Synthesis and functional properties

Biocompatible composite hydrogels based on polyacrylamide and reinforced with bacterial or vegetable cellulose were synthesized. In the mechanical characteristics and water content, these hydrogels are similar to knee joint cartilages with average rigidity level. The structure and chemical composition of the hydrogels after their residence for 45 days in laboratory animal joints were studied by scanning electron microscopy and energydispersive X-ray microanalysis. Prolonged contact of the hydrogels with bones results in formation of calcium phosphate spherulites similar in composition to hydroxyapatite.     

A carbon-silica composite material based on powdered cellulose: Synthesis and properties

A procedure was developed for preparing a carbon-silica composite by thermolysis of powdered cellulose in the presence of tetraethoxysilane. The resulting composite was studied in model processes of trimethylhydroquinone oxidation and hydrogen peroxide decomposition.     

Synthesis and properties of novel polysulfone bearing exomethylene structure

A novel polysulfone bearing exomethylene structure in the main chain was obtained by oxidation of polysulfide prepared by radical ring-opening polymerization of an eight-membered cyclic allyl sulfide, although the corresponding sulfone monomer was not polymerized at all. The thermal behaviors and the crystalline characters of the polysulfone and polysulfide are compared.     

Dilute solution properties,chain stiffness,and liquid crystalline properties of cellulose propionate

The solution properties of cellulose derivatives are of interest from both technological and purely scientific aspects. At high concentrations these solutions form liquid crystalline structures. In dilute solution cellulosic chains can be described as semiflexible or wormlike with properties intermediate between random coils and rigid rods. A series of fractions of cellulose propionate have been examined by dilute solution viscometry, static and dynamic light scattering, and polarizing microscopy. Power law exponents are considerably larger than those observed for flexible chains and analysis of the intrinsic viscosity and hydrodynamic radii has yielded chain diameters and Kuhn statistical segment lengths. Corresponding aspect ratios from the hydrodynamic measurements are in good agreement with those obtained from polarizing microscopy, as analyzed in light of Flory's theory. Some aggregation and specific solvent effects have been observed, however separation of these effects has proven to be difficult. Results of these studies are compared to previous work for other cellulose derivatives. ©1995 John Wiley & Sons, Inc.     

Synthesis and properties of poly(ester urethanes) based on cellulose triacetate

Segmented poly(ester urethanes) were synthesized from oligomeric cellulose triacetate diols, poly(caprolactone)diols, and 1,6-hexamethylene diisocyanate. The effects of the molecular mass and structure of soft and hard segments of poly(ester urethanes) on their thermal behavior, mechanical properties, and degradation in aqueous solutions of a phosphate buffer were studied by DSC and IR spectroscopy. The combination of soft segments derived from poly(caprolactone)diols with M = (1.0–3.5) × 10³, hard segments based on depolymerized cellulose triacetate with M = (2–4) × 10³, and 1,6-hexamethylene diisocyanate makes it possible to synthesize poly(ester urethanes) with excellent mechanical characteristics. The degree of crystallinity of these polymers increases with a decrease in the molecular mass of the depolymerized cellulose triacetate block in the hard segment. As the soft segment lengthens, phase separation between domains of soft and hard segments becomes more pronounced. Upon incorporation of poly(ethylene glycol) blocks into the soft segments of poly(ester urethanes), their hydrophobicity is enhanced and biodegradability is accelerated.     

Synthesis and properties of cellulose phosphates

Conditions for modification of cellulose under laboratory and industrial conditions with A-1 and A-2 fire retardants as P,N-containing modifiers were examined with the aim to prepare difficultly inflammable materials. The degrees of crystallinity of the products, crystallite size, and features of their thermal decomposition in air in the range 20–500°C were examined. Original Russian Text N.K. Luneva, L.I. Petrovskaya, T.I. Ezovitova, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 11, pp. 1899–1903.     

Theoretical investigations on the structure and physical properties of cellulose

The structure of cellulose is investigated using a recently derived force field. Published experimental data is taken only as a starting point for purely theoretical investigations. The reliability of the method is validated by calculating physical properties of the obtained geometries. In the course of the investigations, the geometries of cellulose Iα, cellulose Iβ and cellulose II are derived. For these geometries the Young's-modulus is calculated. The structure of cellulose in aqueous solution is investigated, using cellohexaose (a hexamer of β-D -glucose) as a fragment of a cellulose chain. Here, the diffusion coefficient is calculated.     

Synthesis, properties, and crystal structure of a novel anthracene-bridged molybdenum-zinc porphyrin dimer

The synthesis and properties of novel anthracene-bridged porphyrin dimers having an oxomolybdenum(V) porphyrin unit, H(2)(DPA)[Mo(V)O(OMe)] (1) and (DPA)[Mo(V)O(OMe)][Zn(II)(MeOH)] (2), and the relevant monomer porphyrin complexes Mo(V)O(MPP)OMe (3) and Zn(II)(MPP) (4) are presented. An oxomolybdenum(V) unit was introduced into one of the two porphyrins in DPA to give 1, which has a free-base porphyrin unit. By introducing a zinc(II) ion to the free-base part, a mixed-metal complex of 2 was prepared and isolated. The structure of 2 was analyzed by X-ray crystallography (2.(7)/(6)CH(2)Cl(2), triclinic, P(-)1 (no. 2), a = 15.2854(12) A, b = 19.9640(15) A, c = 13.6915(12) A, alpha = 90.968(3), beta = 113.108(4), gamma = 96.501(4), Z = 2, R1 = 9.9, wR2 = 19.2). The structure of 2 demonstrated that a methanol is stably coordinated to the Zn(II) ion with the aid of a hydrogen bond to the methoxo ligand on the Mo(V) ion in the binding pocket of DPA. The electrochemical measurements of 2 suggested that the methanol was kept in the pocket of DPA in solution even at the reduced state of the molybdenum ion.     

Synthesis,structure, and properties of a coordination polymer based on N- and O-donors

A ternary coordination polymer, [Cd(L)(pbda)_0.5] _n [HL?=?3,5-bis(2-pyridylmethyl)aminobenzoic acid, pbda?=?dianion of 1,4-benzenedicarboxylic acid], has been synthesized and characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction, thermogravimetric analysis, and single-crystal X-ray diffraction analysis. The single-crystal X-ray crystallography reveals that the complex is a 2-D wave-like network. The cadmium has an unsymmetrical seven-coordinate [CdN₂O₅] geometry, coordinated by two nitrogens and five oxygens from L^? and pbda. Hydrogen bonds between the uncoordinated (2-pyridylmethyl)amino groups from adjacent layers form dimers across the inversion center, superposing different layers to construct a 3-D framework. To the best of our knowledge, [Cd(L)(pbda)_0.5] _n represents the first example of a complex containing 3,5-bis(2-pyridylmethyl)aminobenzoate.     

First coordination polymer based on diterpenoids. Synthesis,structure, and magnetic properties

Russian Chemical Bulletin - One-dimensional coordination polymer was obtained by cation exchange reaction of triethylammonium salt of methyl ent-16α-H-phosphonyloxybeyeran-19-oate with CuCl2....     

Synthesis,structure and nonlinear optical properties of two novel two-photon absorption chromophores

Two triphenylamine-based derivatives that can be used as two-photon absorption chromophore,tris{4-[4-(3-trifluoromethyl-3-oxopanoyl)]phenyl}amine (1) and tris{4-[4-(3-phenyl-3-oxopanoyl)] phenyl} amine (2) were successfully synthesized and fully characterized by elemental analysis,IR,1H NMR and MS. The single crystal X-ray diffraction analysis showed that the molecules possess D-(π-A)3 structures. One-and two-photon absorption and fluorescence in various solvents were experimentally investigated. A data rec...     

Structure and properties of novel fibers spun from cellulose in NaOH/thiourea aqueous solution

Cellulose was dissolved rapidly in a NaOH/thiourea aqueous solution (9.5:4.5 in wt.-%) to prepare a transparent cellulose solution, which was employed, for the first time, to spin a new class of regenerated cellulose fibers by wet spinning. The structure and mechanical properties of the resulting cellulose fibers were characterized, and compared with those of commercially available viscose rayon, cuprammonium rayon and Lyocell fibers. The results from wide angle X-ray diffraction and CP/MAS 13C NMR indicated that the novel cellulose fibers have a structure typical for a family II cellulose and possessed relatively high degrees of crystallinity. Scanning electron microscopy (SEM) and optical microscopy images revealed that the cross-section of the fibers is circular, similar to natural silk. The new fibers have higher molecular weights and better mechanical properties than those of viscose rayon. This low-cost technology is simple, different from the polluting viscose process. The dissolution and regeneration of the cellulose in the NaOH/thiourea aqueous solutions were a physical process and a sol-gel transition rather than a chemical reaction, leading to the smoothness and luster of the fibers. This work provides a potential application in the field of functional fiber manufacturing.     

Synthesis,structure, and properties of Schiff base iodobismuthate and its alteration in DMSO solution

New hybrid iodobismuthates (C₁₂H₁₈N₂)(BiI₄)₂ (1, C₁₂H₁₈N₂ is N,N´-bis(1- methylethylidene)-1,4-benzоdiammonium dication) and (C₆H₄(NH₃)₂) [Bi₂I₈?2DMSO]?4DMSO (2, C₆H₄(NH₃)₂ is p-phenylenediammonium dication) were synthesized and their crystal structures were established. Compound 1 crystallizes in the space group P2₁/n, a = 7.632(4), b = 13.471(6), c = 14.556(5) Å, β = 93.57(4)°; compound 2 crystallizes in the space group P\(\overline 1 \), a = 9.208(4), b = 12.203(5), c = 13.600(5) Å, α = 110.20(3)°, β = 97.28(4)°, γ = 110.04(4)°. In the crystal structure of compound 1, one-dimensional infinite BiI ₄ ^– polyanions are linked into a three-dimensional structure by N,N'-bis(1-methylethylidene)- 1,4-benzоdiammonium dications through N–H…I and C–H…I hydrogen bonds. Compound 1 is stable up to 200 °С, optical studies showed that it has a band gap of 2.15 eV. The recrystallization of compound 1 from DMSO is accompanied by the transformation of chain BiI ₄ ^– anions to binuclear [Bi₂I₈?2DMSO]^2– anions, while the azomethine cation decomposes to form a p-phenylenediammonium dication.