Fracture surface morphology of poly[bis(trifluoroethoxy)phosphazene]

Poly[bis(trifluoroethoxy)phosphazene] (PBFP) films were prepared from tetrahydrofuran solution. Fracture surface morphology was studied by scanning electron microscopy. Two morphologies associated with heat treatment have been established: (a) cospherically grown aggregates are obtained in solution-cast films and films heated through the T(1) transition; (b) aggregates of irregular shaped crystalline platelets obtained after melting and crystallization. Ion etching was also applied to the fracture surface in order to clarify the morphological and structural features. The striations originally associated with the [c] axis direction of PBFP crystals can be accentuated on the fracture surface of original as-cast spherulitic films by employing this technique. The texture of the fracture surface after etching is compared with that obtained for an oriented fibre made from this polymer. From this comparison it can be concluded that the [c] axis direction is perpendicular to the spherulite radius. Furthermore the morphology is analogous in many respects to that of Kevlar.     

Crystal structure of poly[bis(3,4-dimethylphenoxy)phosphazene]

The crystal structure and chain conformation of poly[bis(3,4-dimethylphenoxy)phosphazene] — PB (dMe) PP — have been studied by X-ray diffraction techniques. The unit cell of this polymer shows an orthorhombic form with the crystallographic parameters a=2.05, b=1.49, c (chain axis)=0.998 nm. Its space group is determined as Pbcn-D _2h ¹⁴ where the molecular chains are located at the centre and each corner of the unit cell, which contains eight monomeric units; these molecular chains possibly have a — (trans ₃ cis)₂-conformation. The R factor calculated from the final crystal structure was estimated as 16.9%. As with other types of polyorganophosphazenes, the thermotropic transformation in PB (dMe) PP takes place from the three-dimensionally ordered state to its two-dimensional psuedohexagonal form (a _h = 1.49 nm), accompanied by a latent heat change at 96 °C.     

Low temperature synthesis of a self-assembling composite: hydroxyapatite-poly[bis(sodium carboxylatophenoxy)phosphazene]

The present study was undertaken to investigate the low temperature formation of a hydroxyapatite-polyphosphazene polymer composite likely to be biocompatible. The temperature range studied (25 to 60°C) was selected to bracket physiological temperatures. The composite precursors consisted of CaHPO₄·2H₂O, Ca₄(PO₄)₂O, and poly[bis(sodium carboxylatophenoxy)phosphazene]. The results indicate that a synergistic relationship exists in the formation of a polyphosphazene network and hydroxyapatite (HAp) matrix phase during composite synthesis. Calcium from the HAp precursors participates in the formation of a Ca crosslinked polymeric network which influences the rate of HAp formation and its morphology. The mechanistic paths taken during composite formation were followed by determining variations in the concentration of species in solution (at physiological temperature), rates of heat evolution, and microstructural development. These analyses indicate that the polymer controls the kinetics of hydroxyapatite formation and the composite microstructure. Low reaction temperatures and a high proportion of polymer facilitate the formation of a highly interconnected composite. The presence of the polyphosphazene allows a metastable calcium phosphate solution to persist for extended periods prior to the formation of hydroxyapatite. The degree of supersaturation and the length of the induction period increase with an increase in polyphosphazene content. The temperature dependence of these induction periods obeyed an Arrhenius relationship.     

Electrical properties of poly(n-butylamino) (di-allylamino) phosphazene

A new organic–inorganic hybrid polymer, poly(n-butylamino) (di-allylamino) phosphazene, is synthesized and electrical properties of the polymer are reported. From the results of Fourier transform infrared (FTIR), 1H-nuclear magnetic resonance (NMR) and 31P-NMR measurements, it was confirmed that the synthesized polymer was poly(n-butylamino) (di-allylamino) phosphazene. From an Arrhenius plot of d.c. conduction it was found that experimental points fit to two straight lines, that the discontinuous point could be the glass transition (Tg=268.9 K) and that the activation energies are 0.74 and 1.5 eV at temperatures higher and lower than Tg, respectively. Dielectric constant and dielectric loss factors were measured over the temperature range from –20°C to 70°C with frequency 100 Hz100 kHz, and a dielectric loss contour was obtained. A relaxation process with the activation energy of 1.44 eV was found from the dielectric loss contour, which can be attributed to relaxation. A comparison was made between the present results and those of other phosphazene polymers. Because the polymer was non-flammable and shows high resistance and low dielectric constant, it could be used as an insulator in the field of electronics. © 1998 Kluwer Academic Publishers     

Sol–gel hybrid materials based on hydroxylatedpoly[bis(methoxy–ethoxy–ethoxy)phosphazene] and silica: a ceramic ionic conductor

The sol–gel synthesis of hybrid materials based on poly[bis(methoxy–ethyoxy–ethoxy) phosphazene] (MEEP) and silica and their characterization are described. MEEP is a polymer with a low glass transition temperature of −71 °C, that bears ethyleneoxide oligomers as phosphorus side groups, able to impart to the macromolecule metal co-ordination ability. This property makes MEEP an ionic conductor, but unfortunately its flow behaviour at room temperature limits its industrial development. The linkage of MEEP to a rigid inorganic network, which would overcome this problem, was pursued using the sol–gel method. The functionalization of MEEP by the introduction of free hydroxyl groups allows the formation of chemical bonds with hydrolysed tetraethoxysilane. Phosphazene-based hybrid materials with no phase separation could be obtained by this procedure. The ionic conductivity of these materials doped with lithium triflate has been investigated using a.c. impedance techniques. A conductivity value of about 3 × 10^-5 Ω^-1 cm^-1 was measured which is comparable to typical values of poly(ethylene oxide) solid electrolytes. A thermal treatment of the Li-doped samples decreases the conductivity but it still remains above 5 × 10^-6 Ω^-1 cm^-1. This revised version was published online in November 2006 with corrections to the Cover Date.     

Charge injection into poly[methyl(phenyl)silylene]

Space-charge-limited currents have been measured in thin films of poly[methyl(phenyl)silylene] provided with Al and hole-injecting ITO electrodes. Electroluminescence observed at high voltages was interpreted as being due to a double injection. The thermo-modulated space-charge-limited current technique has been employed to determine the structure of traps in the low-voltage (single-injection) regime.     

Polybis(pyrrolyl)phosphazene

Poly(pyrrole) may be prepared by electrochemical or chemical systhesis, and under appropriate conditions, free-standing films of the oxidized material are produced, which exhibit relatively high conductivity and stability. This material provides an interesting contrast with the phosphazene polymers. Although the polyphosphazene are completely conjugated, all of the currently known materials are insulators; nevertheless the polyphosphazenes exhibit excellent mechanical and chemical stability properties. In the present study we report the synthesis of polybis(pyrrolyl)phosphazene (PBPP), a new polymer which incorporates certain features of both classes of materials. Subsequent electrochemical oxidation of PBPP leads to the deposition of electrically conducting fibrous black films at the anode.     

Plastic deformation mechanisms in poly(acrylonitrile-butadiene styrene) [ABS]

Thin films of two poly (acrylonitrile-butadiene-styrene) [ABS] resins have been strained in tension, and the ensuing deformation has been characterized by transmission electron microscopy. To enhance contrast of the rubber particles, some of the specimens were stained with OsO₄. Films containing only solid rubber particles 0.1 m in diameter show little tendency for crazing. Instead, cavitation of the rubber particles occurs, together with localized shear deformation between the particles along a direction nearly normal to the tensile axis. For specimens containing a mixture of the same small particles plus larger (1.5m diameter) particles containing glassy occlusions, some crazing does occur. Crazes tend to nucleate at the larger particles only. When crazes encounter the smaller particles these cavitate without appearing to impede or otherwise affect the craze growth. The occluded particles also show significant cavitation, with voids forming at their centres at sufficiently high levels of strain. These voids do not seem to lead to rapid craze break-down and crack propagation. In commercial ABS, which typically has both large and small rubber particles, both crazing, nucleated by the large particles, and shear deformation, encouraged by the cavitation of small rubber particles, can be expected to make important contributions to the toughness of the polymer.     

Mechanochromic luminescence of 4-[bis(4-methylphenyl)amino]benzaldehyde

The title compound was found to exhibit mechanochromic luminescence; the fluorescent color of the crystalline powder was changed from light blue to greenish yellow by grinding and then returned to the original by keeping at room temperature. The phenomenon was suggested to be due to formation of the supercooled liquid state of the material by grinding and following recrystallization.     

Oxygen gas permeability and the mechanical properties of poly (n-butylamino)-(di-n-hexyamino) phosphazene Membranes

Poly (n-butylamino)-(di-n-hexylamino)-phosphazene was prepared by the reaction of poly (dichlorophosphazene), di-n-hexylamine and n-butylamine using tetrahydrofuran (THF) solvent and triethylamine at room temperature. To increase the mechanical properties of polymer films, cross-linking agents, such as neopentyl glycidyl diether and trimethylol propane triglycidyl diether, were added to the original polymer. The original and agent-added polymer films were prepared by a casting method. The films with cross-linking agents were heated at 60 and 120 °C, and then transparent films were prepared. The oxygen gas permeability and the mechanical properties of the original and the cross-linked films were determined. It was found that the oxygen gas permeability and the mechanical properties, such as Young's modulus, of the cross-linked films were greater than for the original film.     

多糖介质中分散聚合法合成P(PEGDA)凝胶微球

以聚乙二醇双丙烯酸酯(PEGDA)为单体,过硫酸铵(APS)为引发剂,N,N'-亚甲基双丙烯酰胺(BIS)为交联剂,聚乙烯吡咯烷酮(PVP)为分散剂,在一定比例的壳聚糖多糖介质中,用分散聚合法制备P(PEGDA)凝胶微球.采用傅立叶红外光谱仪及扫描电镜对微球成分和形貌进行了表征,并研究了反应时间、反应温度、KCl用量和...     

Construction of new iodide selective electrodes based on bis(trans-cinnamaldehyde)1,3-propanediimine(L) zinc(II) chloride [ZnLCl2] and bis(trans-cinnamaldehyde) 1,3-propanediimine(L) cadmium(II) chloride [CdLCl2]

New plasticized PVC membranes iodide selective electrodes have been prepared by incorporating bis(trans-cinnamaldehyde)1,3-propanediimine zinc(II) chloride [ZnLCl2] and bis(trans-cinnamaldehyde) 1,3-propandiimine cadmium(II) chloride [CdLCl2] on the surface of graphite disk electrodes. At optimum value of variables the proposed electrodes have selective response to iodide with respect to a number of inorganic and organic anions with near-Nernstian slopes of − 60 ± 1.9 and − 58.5 ± 1.9 mV/decade of iodide concentration over the range 1.0 × 10^− 6-1.0 × 10^− 1 M with detection limits of 4.0 × 10^− 7 and 3.0 × 10^− 7 M for the electrodes based on [ZnLCl₂] and [CdLCl₂], respectively. The electrodes based on both ionophores have response times of about (6 s), with stable reproducible response during 2 months, while their responses is independent of pH over the range 2.5-10.5. The proposed electrodes successfully have been applied for evaluation of iodide ion content in real samples with complicated matrices including water and pharmaceutical samples.     

聚[9-甲基-9-(8-硫代乙酸辛酯基)-芴]的合成及其金纳米粒子复合物

合成了一种新型的侧链含硫代乙酸辛酯基的聚芴衍生物,聚[9-甲基-9-(8-硫代乙酸辛酯基)-芴](PFMOTA).用这种聚合物修饰金纳米粒子,得到了稳定的PFMOTA/金纳米粒子复合物.采用TEM、GPC、FTIR、UV-vis和PL光谱对聚合物及其修饰的金纳米粒子复合物的结构和性能进行了表征.