Polymer In Solid State Research Articles

The Synthesis and Characterization of a Novel One-Dimensional Bismuth (III) Coordination Polymer as a Precursor for the Production of Bismuth (III) Oxide Nanorods

A novel Bi (III) coordination compound, [Bi(HQ)(Cl)4]n ((Q = pyridine-4-carbaldehyde thiosemicarbazone), was prepared in this research using a sonochemical technique. SEM, infrared spectroscopy (IR), XRD, and single-crystal X-ray analysis were utilized to analyze the Bi(III) coordination compound. The structure determined using single-crystal X-ray crystallography indicates that the coordination compound is a 1D polymer in solid state and that the coordination number of bismuth (III) ions is six, (BiSCl5), with one S donor from the organic ligand and five Cl donors from anions. It is equipped with a hemidirectional coordination sphere. It is interesting that the ligand has been protonated in the course of the reaction with a Cl- ion balancing the charge. This compound’s supramolecular properties are directed and regulated by weak directional intermolecular interactions. Through π–π stacking interactions, the chains interact with one another, forming a 3D framework. Thermolysis of the compound at 170 °C with oleic acid resulted in the formation of pure phase nanosized Bi (III) oxide. SEM technique was used to examine the morphology and size of the bismuth (III) oxide product produced.

Supersaturating drug delivery systems containing fixed-dose combination of two antihypertensive drugs: Formulation, in vitro evaluation and molecular metadynamics simulations

The purpose of this study was to associate the poorly water-soluble antihypertensive drugs candesartan cilexetil (CC) and hydrochlorothiazide (HCTZ) as fixed-dose combination, in the form of ternary Amorphous Solid Dispersions (ASD), using hydroxypropylmethylcellulose acetate succinate (HPMCAS) type M as polymeric carrier. The potential of the system to generate and to maintain supersaturation of both drugs was also evaluated. The ASDs were prepared by ball milling technique and solid-state characterization was performed by differential scanning calorimetry (DSC), Fourier transformed infrared spectroscopy (FTIR) and X-ray powder diffraction (XRPD). Interaction between drugs and polymer in solid-state was evaluated by molecular metadynamics simulations. In vitro supersaturation profiles were determined in biorelevant medium. Physicochemical stability of ASDs was also evaluated under different storage conditions. Amorphization of both drugs was confirmed by solid-state characterization techniques. Molecular metadynamics simulations indicated that CC has stronger interaction with HMPCAS than HCTZ. In vitro supersaturation studies have shown that ternary ASDs could generate and maintain supersaturation of both drugs in biorelevant medium. The polymer reduced the desupersaturation of both drugs. Ternary ASDs also showed physicochemical stability over a period of 90 days, demonstrating the potential of the polymer in reducing the drugs recrystallization over the time. Ternary ASDs of CC, HCTZ and HPMCAS can be considered a promising system to associate the drugs as fixed-dose combinations. Also, these systems generate and maintain supersaturation of both drugs in biorelevant medium, with great storage stability. HPMCAS M was a good carrier for reducing the desupersaturation of associated HCTZ and CC.

Solid-State Low-Temperature Thermoresponsive and Reversible Color Changes of Conjugated Polymer in Layered Structure: Beyond Infrared Thermography.

Emergence of thermoresponsive and reversible color changes at low temperature is a challenging target. In general, it is not easy to induce sufficient dynamic motion of rigid molecules including chromophore at a lower temperature. The present work shows unusually low-temperature color-change properties originating from the dynamic motion of rigid conjugated polymer in solid state. The layered composites of polydiacetylene (PDA) and guest l-arginine (L-Arg) (PDA-(L-Arg)) exhibit temperature-responsive gradual color changes with reversibility in the range of 123-333 K in solid crystalline state. The dynamic properties are induced by gradual and reversible distortion of the π-conjugated main chain in response to temperature. The tuned flexibility of the layered structure facilitates motion of the rigid π-conjugated molecule at low temperature. The PDA-(L-Arg)-coated substrates are applied to visualization and quantification of 2D and 3D temperature distributions generated by cooling with liquid nitrogen. These thermographic devices afford to image lower temperature range than typical infrared thermography. The present work indicates potentials of layered architectures with tunable flexibility for emergence of dynamic properties.

Improved Fluorescence of Fluorene Polymer in Solid State

Fluorene-containing poly(aryl ether nitrile) (FPAN) was prepared by a typically aromatic nucleophilic substitution polymerization. The chemical structure of FPAN was confirmed by FTIR and 1H NMR spectroscopy. Different morphologies of FPAN fibers could obtain through electrospinning. The light-emission properties of polymer in solution, casting film and fibrous membrane were examined by spectrofluorometry. This polymer had good thermal properties with glass-transition temperatures at 280 °C and 10 % weight loss temperatures in the range of 497–502 °C. Additionally, the contact angles in the thin-film state and electrospun fiber membranes were examined. The water contact angle of fiber membrane was improved compared to that of casting film which could reach to the 137 °. The resulting material exhibited stable luminescent intensity, possessed considerable thermal stability, and could be facilely processed into device for optical field applications.

Solid state NMR and computational studies on cyclopentadienyl lithium.

Lithiumcyclopentadienide, previously identified to be an endless polymer in the ligand-free solid state, was investigated by 13C- and 6Li-CP/MAS NMR spectra, and by B3LYP-GIAO theoretical calculations. By spectra simulation, the axially symmetric 13C-shift tensor components were identified to be δ11 = δ22 = 151.5ppm, δ33 = 15.5ppm. The 6Li-tensor components are δ11 = δ22 = +1.0ppm, δ33 = -43.0ppm. This extremely high field component is due to cumulative ring current effects. B3LYP-GIAO/TZVP calculations on the tensor principal components agree remarkably well with the measurements. A new and very simple method of preparing air-sensitive compounds for solid-state NMR analyses is described. Graphical abstract Shielding tensor main components from slow-speed solid state NMR spectra.

Preparation of a Novel Nano-scale Lead (II) Zig-Zag Metal–Organic Coordination Polymer with Ultrasonic Assistance: Synthesis, Crystal Structure, Thermal Properties, and NBO Analysis of [Pb(μ-2-pinh)N3 H2O

A novel nano-cauliflower-shaped lead(II) metal–organic coordination polymer, [Pb(μ-2-pinh)N3 H2O]n (1), was synthesized using an ultrasonic method. The nanostructure was characterized by scanning electron microscopy (SEM), X-ray powder diffraction, IR spectroscopy, elemental analysis, and thermal analysis. The compound was structurally characterized by single-crystal X-ray diffraction. The coordination compound takes the form of a zig-zag one-dimensional polymer in solid state. The coordination number of the lead(II) ions is six (PbN4O2) with three nitrogen atoms and one oxygen atom from two linker organic ligands, as well as one oxygen from coordinated water and one nitrogen atom from terminal coordinated azide anion. It has a stereo-chemically active lone electron pair, and the coordination sphere is hemidirected. The zig-zag 1D chains interact with neighbouring chains through weak interactions, creating a 3D supramolecular metal–organic framework. Lead oxide nanoparticles were obtained by thermolysis of the new nano coordination compound at 180 °C with oleic acid as a surfactant. The morphology and size were further studied using SEM. Natural bond orbital analyses demonstrate the electronic properties of the lead centre and other atoms.

Enhancement of dissolution rate of class II drugs (Hydrochlorothiazide); a comparative study of the two novel approaches; solid dispersion and liqui-solid techniques

Liqui-solid technique and solid dispersion formation are two novel approaches for enhancement of dissolution rate of BCS class II drugs. Liqui-solid compact converts a liquid drug or drug solution into a free flowing powder with enhanced dissolution rate. In case of solid dispersion drug is molecularly dispersed in a hydrophilic polymer in solid state. In the present study, Liqui-solid and solid dispersion techniques were applied to enhance the dissolution of the Hydrochlorothiazide. Three formulations of Hydrochlorothiazide were prepared by liqui-solid technique using micro crystalline cellulose as carrier material and colloidal silicon dioxide as coating material. Water, poly ethylene glycol-400 and Tween-60 were used as solvent system. Solid dispersions of Hydrochlorothiazide were prepared by solvent fusion method using PEG-4000 as carrier polymer. Tablets were subjected to evaluation of various physical and chemical characteristics. Dissolution profiles of tablets prepared by the novel techniques were compared with marketed conventional tablets. Model independent techniques including similarity factor, dissimilarity factor and dissolution efficiency were applied for comparison of dissolution profiles. The results obtained indicated that liqui-solid compact formulations were more effective in enhancing the dissolution rate compared with solid dispersion technique. The liqui-solid compacts improved the dissolution rate up to 95% while the solid dispersion increased it to 88%.

IV―1―1 非弾性・準弾性中性子散乱による高分子固体のダイナミクス

低速中性子は，物質中の原子・分子運動のエネルギーと同じ程度のエネルギーを有するため，散乱過程においてエネルギーのやり取り・すなわち非弾性・準弾性散乱が起こる。高分子を含むソフトマターは，分子が持つ自由度故に非常に広い時間・空間スケールにおいてダイナミクスが構造と同様に階層的に存在する。しかしながら小角散乱などにより行われる構造解析と比較すると，ソフトマター系における中性子によるダイナミクス測定はそれほど活発に行われていない。ソフトマターの機能・物性を十分に理解するためには構造のみならずダイナミクスを調べることが必要不可欠である。本稿においては，主に固体状態の高分子のダイナミクスに注目して，(1)低エネルギー励起，(2)結晶弾性率の評価，(3)局所緩和過程“速い過程”，(4)ガス透過と局所的ダイナミクスとの相関の4点を選び解説した。

Comparison of Isothermal with Nonisothermal Kinetics for Ethylene-Vinyl Acetate Cross-Linking Reaction in the Solid State

Cross-linking reaction kinetics of ethylene-vinyl acetate (EVA) copolymer initiated with dicumyl peroxide is studied by differential scanning calorimetry (DSC) and a cross-linking rheometer. As the degree of cross-linking (α) is less than 0.30, EVA can flow relatively freely because of insufficient cross-linking. As α ranges from 0.31 to 1, there is more of the cross-linking reaction, and the polymer becomes fully cross-linked in the later stage of the reaction so that three-dimensional cross-linked nets have been constructed. New kinetics approaches are proposed on the basis of the cross-linking parameters measured with the cross-linking rheometer incorporated into Hill and Avrami mathematical equations. As the cross-linking rheometer is popular in manufacturing the cross-linked EVA, the approaches are simpler and more convenient than the DSC method for fast studying kinetics of the cross-linking reaction of polymer in solid or melting state. The total cross-linking reaction rate changes with α, and the apparent activation energy is 91.2–175.0 kJ/mol.

Unique UV absorbance for triphenylimidazole‐based polymer

AbstractIn this study, a novel vinyl polymer containing 2,4,5‐triphenylimidazole side groups was synthesized through conventional radical polymerization, which possesses the characteristic of temperature‐dependent absorbance in the near‐ultraviolet (UV) spectral region. The linear dependence of UV absorbance on temperature was confirmed for the polymer both in solid state and in solution by experiment and also supported by the results of theoretical investigation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Optically anisotropic and photoconducting Langmuir–Blodgett films of neat poly(3-hexylthiophene)

Among the several types of conjugated polymers used in recent investigations, polythiophene and its derivatives have attracted considerable attention over the past 20 years due to their high mobility and other remarkable solid-state properties. They have potential applications in many fields, such as microelectronic devices, catalysts, organic field-effect transistors, chemical sensors and biosensors. There are two critical parameters that determine the polymer-based device performance: chemical structure and nanostructure of the conjugated polymer in solid state. Langmuir–Blodgett (LB) films may be an interesting alternative for producing the films used in the devices since they can be obtained with high degree of thickness control, low number of defects, and some degree of organization at the molecular scale. However, most of the polythiophene derivatives have poor film forming properties by LB method and need the use of film form aiding materials. In this work, we report on the fabrication and characterization of Langmuir and Langmuir–Blodgett films of neat poly(3-hexylthiophene). Although the LB technique is not suitable to obtain LB films with a great number of layers, good quality films, with thicknesses suitable for fabrication of opto-eletronic devices could be easily built by using the proper deposition conditions.

Doped polypyrrole for MAPLE deposition: Synthesis and characterization

The contribution deals with synthesis and characterization of conductive polypyrrole (PPY), which should be suitable for depositions of thin layers by Matrix Assisted Pulsed Laser Evaporation (MAPLE) method. The samples of doped PPY containing various organic dopants – (i) p-toluenesulfonic acid, (ii) dodecyl-benzenesulfonic acid, (iii) dioctyl-sulfosuccinic acid and (iv) camphorsulfonic acid – were synthesized by polymerization of pyrrole in acidic or neutral solution. Solubility of synthesized PPY and settlement time of PPY particles in water and dimethylsulfoxide – parameters critical for MAPLE method – were investigated. The composition of prepared PPY was verified by FTIR spectroscopy. Conductivity of the polymer in solid state was determined to be in range from σ = 2.6 × 10 −6 S cm −1 to σ = 6.0 × 10 −2 S cm −1. The optimal material for MAPLE deposition is PPY containing organic dopants (ii)–(iv), dissolved in DMSO matrix (solubility from 4.1% to 6.5% by weight and settlement time 140–240 h).

Spectroelectrochemical Study of Electron and Energy Transfer in Poly(fluorene-alt-phenylene) with Perylenediimide Pendant Groups

Electrochemical and spectroelectrochemical studies have been performed on a (fluorene-alt-phenylene) polymer with perylenediimide pendant groups. This polymer can be p-doped by oxidation of the conjugated chain, whereas the reduction occurs on the electron-acceptor perylenediimide units. The photoluminescence of this polymer in solid state is greatly inhibited by a photoinduced electron transfer from the conjugated chain to neutral perylenediimide aggregates. Several changes have been observed in the emission from polymers upon electrochemical treatments. On the other hand, the oxidation of the main chain induces the quenching of the remaining emission from the conjugated fluorophoric main chain, whereas the emission from the side groups is not affected. Remarkably, the evolution of the emission of the perylenediimide pendant groups upon electrochemical reduction allows discrimination between aggregated and nonaggregated perylenediimide groups in the polymer. As a result of the formation of the perylenedi...

A two-dimensional copper(II) polymer with bridging μ- trans-oxamidate and μ 2-picrate ligands: Synthesis, crystal structure and DNA binding studies

A two-dimensional copper(II) polymer with formula of [Cu 2(dmapox)(pic) 2] n · nCH 3OH, where dmapox is the dianion of N, N′-bis[3-(dimethylamino)propyl]oxamide and pic is picrate, was synthesized and characterized by elemental analysis, conductivity measurement, IR and electronic spectra studies. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P2 1/ c with crystallographic data: a = 14.076(7) Å, b = 13.896(7) Å, c = 9.278(5) Å, β = 106.909(6)° and Z = 2. The structure consists of uncoordinated methanol molecules and two-dimensional copper(II) polymeric coordination network constructed by the bis-tridentate trans-dmapox and tridentate picrate ligands. The environment around the copper(II) atom can be described as a distorted octahedron and the Cu⋯Cu separations through μ- trans-oxamidate and μ 2-picrate bridges are 5.227 Å and 8.359 Å, respectively. The copper(II) complex presents as a polymer in solid state, whereas in solution it presents as discrete neutral binuclear copper(II) species [Cu 2(dmapox)(pic) 2] due to the weak interactions between the copper(II) atoms and the para-nitro oxygens of the adjacent picrate ligands. The fluorescence titration and the ethidium bromide (EB) fluorescence displacement experiments reveal that the binding mode between the binuclear copper(II) complex [Cu 2(dmapox)(pic) 2] and Herring Sperm DNA might be intercalation.

Conformational Structure of N-Methyl-8-octanelactam and Poly(N-methyl-8-octanelactam) as Studied by NMR, Infrared and Raman Spectroscopy and by Theoretical Calculations

It was proved by 1H and 13C NMR spectra that in N-methyl-8-octanelactam in CDCl3 solution, the amide bond assumes only the cis form. Mirror inversion about the plane of the amide bond occurs with an activation enthalpy ∆H# = 44.7 kJ/mol. Molecular mechanics and quantum mechanical calculations yielded four favoured conformational structures for the isolated molecule. By vibrational spectra, one of two distinguishable structures strongly predominates. From 1H NMR spectra, this predominant conformation was identified with one of the calculated stable forms. By 13C NMR evidence, poly(N-methyl-8-octanelactam) in tetrachloroethane solution contains equal populations of the cis and trans amide forms; the structure of this polymer in the rubbery solid state seems to be similar to its structure in solution.