Class Of Poly Research Articles

Synthesis and properties of novel thermoplastic poly(urethane-imide)s

A new class of poly(urethane-imide)s (PUI) thermoplastic elastomers were synthesized via the reaction of NCO terminated polyurethane with imide containing chain extender diols. The prepared chain extenders and polymers were characterized by conventional methods, and physical properties such as solution viscosity, solubility property, thermal stability and thermal behavior were studied. Compared to typical polyurethanes, these polymers exhibited better thermal stabilities due to the presence of the imide groups.

Optical properties and electroluminescence of poly(3-alkylmethoxy-thiophene) single- and double-layer structures

The optical properties of a new class of poly(3-alkymethoxythiophene)s is reported for polymers with different side chain lengths. The different thermal dependence of their photoluminescence is coherently related to the different structural properties of the polymers, as detected by thermal analysis. We observe a higher electroluminescence efficiency for the polymer showing a thermal transition below the melting point, which may be related to its high degree of side chain mobility during the emission.

Surface and bulk phenomena in conjugated polymers devices

We report a number of investigations into a variety of surface and bulk phenomena which are particularly relevant to the design of polymer optoelectronic devices, and in particular to light-emitting diodes (LEDs). First, we consider the surface properties of the most common anode, a thin layer of indium tin oxide (ITO), as modified by chemical and physical treatments. We show how the treatments affect the electrode workfunction, surface energy, morphology, sheet resistance and therefore, the LEDs efficiency and lifetime. We will also consider the effect of a conducting polymer hole-transport layer, such as poly(styrene sulfonate) doped poly(3,4-ethylene dioxythiophene) (PEDOT), incorporated between the ITO and the active layer. Secondly, we turn our attention to the optimisation of the photoluminescence (PL) efficiency, and report examples of how the polymer microstructure and possibly the engineering of disorder in a class of poly(p-phenylene vinylene)s and poly- or oligo-thiophenes can determine a significant increase of the PL efficiencies in the solid state.

Multiblock copolymers based on segments of poly (D,L-lactic-glycolic acid) and poly(ethylene glycol) or poly(?-caprolactone): A comparison of their thermal properties and degradation behavior

A comparison of the thermal properties of two classes of poly(D,L-lactic-glycolic acid) multiblock copolymers is reported. In particular, the results of differential scanning calorimetry, and thermogravimetric analysis of copolymers containing poly(ethylene glycol) (PEG) or diol-terminated poly(ϵ-caprolactone) (PCDT) segments are described. The influence of the chemical structure and the length of PEG and PCDT on thermal stability, degree of crystallinity and glass transition temperature (Tg ) is discussed. Finally, an evaluation of the hydrolytic behavior in conditions mimicking the physiological environment is reported. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1721–1728, 2000

Polarizing Energy Transfer in Photoluminescent Conjugated Polymers with Covalently Attached Sensitizers

A new class of poly(p-phenyleneethynylene) (PPE) polymers, COU-OPPE and ANT-OPPE, have been prepared, in which coumarin- and anthracene-based sensitizer molecules are covalently linked to the conjugated polymer backbone via a flexible spacer. In dilute solutions of these polymers, efficient resonance energy transfer is observed from the sensitizer moieties to the PPE backbone, resulting in enhanced luminescence of the PPE macromolecules. Also, when incorporated as guests in oriented polyethylene films, the novel polymers, COU-OPPE and ANT-OPPE, show efficient energy transfer from the pendent sensitizer to the PPE backbone. Especially in the case of ANT-OPPE, we found that the PPE backbone is efficiently oriented while the anthracene moiety remains essentially isotropic, which results in a high degree of polarizing energy transfer for this system.

New Aspects of the Preparation and Polymerization of Cl 3PNP(O)Cl 2

The DeJaeger synthesis of poly(dichlorophosphazene), (NPCl 2)n (1) from P-trichloro-N-(dichlorophosphoryl)monophosphazene, Cl 3P=NP(O)Cl 2 (2) represents an attractive alternative to the ring opening polymerization approach to 1. We have followed the Emsley reaction, i.e. PCl 5 and (NH4)2SO4, under a variety of conditions by 31P NMR spectroscopy. Alternative oxygen atom sources in place of (NH4)2SO4 were also explored. Model reactions to identify specific pathways potentially operating in the formation of 2 when combined with the NMR studies allow for identification of the most probable sequence of steps leading to 2. Conversion of 2 to 1 under different conditions was also examined. Molecular weight was monitored as a function of time by GPC with online direct detection of the diphenoxy derivative, [NP(OC6H5)2]n, of 1. The byproduct of the polymerization of 2 is POCl 3. After conversion of 2 to (RO)3PO, a one step process has been developed for conversion into (RO)3P=NSiMe3, another class of poly(phosphazene) precursors.

Novel poly(ethylene glycol)-grafted, cationic hydrogels: preparation, characterization and diffusive properties

A new class of poly(ethylene glycol)-grafted, cationic hydrogels was prepared by copolymerization and simultaneous crosslinking of diethylaminoethyl methacrylate (DEAEM) and poly(ethylene glycol) monomethacrylate (PEGMA). The ensuing hydrogels, P(DEAEM-g-PEG), exhibited a strong swelling ratio dependence on pH. At low acidic pH values they expanded to swelling ratios of up to 25, depending on the crosslinking density and feed ratio of the two comonomers. At alkaline pH values they tended to collapse excluding a significant quantity of the incorporated water. This swelling/deswelling process and the associated size can be used for the development of carriers for modulated drug delivery. Proxyphylline, vitamin B 12, and various dextrans diffusion studies were used to elucidate the effect of the gel mesh size on the solute diffusion coefficient.

A new class of poly(1,6-heptadiyne)-based photorefractive materials by metathesis polymerization

We utilized the first metathesis reaction to synthesize a new type of photorefractive polymers that contain both a carbazole moiety as a hole transporter and NLO chromophores. These polymers have a long tail band at above 700 nm, indicating the formation of intramolecular charge transfer complexes between the carbazole groups and the conjugated double bonds in the polymer backbone. Also, these polymers show two maximum values of photocurrent around 350 and 700 nm. The electro-optic coefficient (r 33 ) at the wavelength of 1.3 μm for polymer thin films poled around the 85°C were in the range of 1.6 ∼6.3 pm/V The hyperpolarizabilities, , of the resulting polymers were ca. 2.9 x 10 -32 esu. at the incident wavelength of 1.907 μm.

Synthesis and properties of poly(amide‐imide‐urethane) thermoplastic elastomers

A new class of poly(amide-imide-urethane) thermoplastic elastomers based on two-step synthesis of 4,4′-methylene bis(4-phenylisocyanate) with different polyols (PPG and PTMG) and trimellitic anhydride was synthesized. Both resulting polymers showed semicrystalline structures and were readily soluble in polar solvents such as N-methyl-2-pyrrolidone and dimethyl formamide. The soluble poly(amide-imide-urethane)s afforded transparent, flexible, and tough films. Both new copolymers were then characterized by FTIR spectroscopy, universal tensile tester, simultaneous DTA/TGA (SDT), differential scanning calorimetry (DSC), and wide-angle X-ray diffraction studies, to determine their morphological structures, thermal stability, and mechanical properties. Compared to typical polyurethanes, these polymers exhibited better thermal stabilities due to the presence of imide groups. DSC and X-ray diffraction studies showed semicrystalline patterns for these polymers. Stress–strain properties revealed that these polymers have good extensibility like typical polyurethanes. © 1998 SCI.

Synthesis, structure, and properties of hybrid organic-inorganic composites based on polysiloxanes. I. Poly(dimethylsiloxane) elastomers containing silica

Various synthetic protocols were used to prepare several classes of poly- siloxane-silica filler systems. The structures of these fillers and their interactions with the polysiloxane matrices were studied using small-angle X-ray and neutron scattering. In addition, the mechanical properties of the composites were characterized using equi- librium stress-strain isotherms in elongation. The results indicated that manipulation of the chemical reactions used to generate the filler can lead to a wide range of complex structures and unusual properties. Some of the observed mechanical properties were correlated with information on the composite structures and on elastomer-filler inter- actions. q 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1167-1189, 1998

Tdd-3, a tRNA gene-associated poly(A) retrotransposon from Dictyostelium discoideum.

The full-length 5218-bp sequence of the mobile genetic element Tdd-3 from Dictyostelium discoideum is described. Tdd-3 encodes two overlapping open reading frames (ORFs) flanked by non-redundant, untranslated regions. The deduced amino acid sequence of ORF2 is homologous to reverse transcriptases (RTs) encoded by the class of poly(A) retrotransposons. ORF2 also encodes a putative protein domain related to the family of apurinic/apyrimidinic (AP) endonucleases, whose retroelement-encoded homologs have recently been proposed to represent the integrase function of poly(A) retrotransposons. Comparison of several genomic Tdd-3 copies revealed that element insertion is orientation specific and occurs about 100 bp downstream of tRNA genes in the D. discoideum genome. These properties of Tdd-3 suggest that the element is a tRNA gene-associated poly(A) retroelement present in the D. discoideum genome. Analysis of several cloned cDNAs derived from Tdd-3-specific plus strand RNAs indicate that the element is transcribed and polyadenylated during the growth of D. discoideum cells.

Poly(alkylbenzyls), a promising new polymeric material

The reaction of mesitylene substituted by alkyl or alkoxy chains of various lengths and α,α′-dichloro-p-xylene with K10 Montmorillonite as catalyst affords a new class of poly(alkylbenzyls) soluble in common organic solvents.

Polyanhydrides 10. Aliphatic polyesters and poly(ester‐anhydride)s by polycondensation of silylated aliphatic diols

AbstractA new class of biodegradable copolyesters was prepared by polycondensation of sebacoyl chloride with mixtures of silylated isosorbide and silylated O,O′‐bis(2‐hydroxyethyl)hydroquinone in bulk. A class of poly(ester‐anhydride)s was synthesized from sebacoyl chloride and mixtures of silylated O,O′‐bis(2‐hydroxyethyl)hydroquinone and silylated 4‐hydroxybenzoic acid. A second class of poly(ester‐anhydride)s was obtained by polycondensation of sebacoyl chloride with mixtures of silylated isosorbide and silylated 4‐hydroxybenzoic acid. The molar ratio of anhydride and ester groups was varied via the proportion of 4‐hydroxybenzoic acid in the feed. All polyesters were characterized by inherent viscosities, elemental analyses, 1H NMR and IR spectra, WAXS and DSC measurements. All polyesters proved to be semicrystalline materials.

Synthesis and spectral, thermal, and photocrosslinking studies of poly(benzylidene phosphoramide ester)s

A new class of poly(benzylidene phosphoramide ester)s containing a photoreactive benzylidene chromophore in the main chain were synthesized from bis(4-hydroxy-3-methoxy benzylidene) acetone with various substituted N-aryl phosphoramidic dichlorides by an interfacial polycondensation technique. The synthesized polymers were characterized by inherent viscosity, IR, and 1H-, 13C-, and 31P-NMR spectroscopy. The molecular weights of these polymers were determined by gel permeation chromatography. These polymers were studied for their thermal stability and photochemical properties. Thermal properties were evaluated by thermogravimetric analysis and differential scanning calorimetry. It was found that halogen-containing polymers show a higher thermal stability than that of nonhalogenated polymers. The photocrosslinking property of these polymers was studied by ultraviolet spectroscopy. The photoreactive benzylidene chromophore in the main chain dimerizes via 2π + 2π cycloaddition reaction to form a cyclobutane derivative and leads to crosslinking. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2151–2157, 1997

New class of poly(vinyl alcohol) polymers as column-chromatography stationary phases for Candida rugosa lipase isoforms separation

The preparation of new stationary phases of cross-linked polyvinyl alcohol esterified with various linear fatty acids is described. The physico-chemical properties of these polymers are reported, including electron microscopy and swelling measurements. Batch adsorption experiments were performed in order to characterize the basic separative properties of these phases. Cross-linked polyvinyl alcohol esterified with dodecanoic acid was used for hydrophobic interaction chromatography of a commercial crude preparation of Candida rugosa lipase. Characterization of the purified fractions was carried out via native electrophoresis and sodium dodecyl sulfate-polyacrylamide electrophoresis.

Synthesis and Characterization of Poly(aryl ether chalcone)s for Second Harmonic Generation

The synthesis of a new class of poly(aryl ether chalcone)s is described by a polycondensation reaction of 4,4‘-difluorochalcone with various bisphenols in the excess anhydrous potassium carbonate in sulfolane/toluene mixture solvent. Fluoride atoms located at the para position of the chalcone moiety were found to be very activated toward nucleophilic aromatic substitution, and high molecular weight polymers were obtained. These polymers are amorphous and with glass transition temperatures at 150−200 °C and are very soluble in solvent such as chloroform and N-methylpyrrolidinone (NMP). The onset decomposition temperatures by thermogravimetric analysis of these materials were all above 330 °C. High optical quality films were obtained by spin-coating the polymer solution of NMP. The cutoff wavelength was shorter than 410 nm. The refractive indexes of these polymers at different wavelengths are reported. The corona poled polymers have different symmetry structures from the reported polymers, both P- and S-pol...

Effects of Chromophore Functionalization and Physical Aging during Poling on Chromophore Orientational Dynamics in Poly(arylene ether)s for Second-Order Nonlinear Optics

The structure/property relationships including the effects of chromophore functionalization and physical aging during poling on the chromophore orientational dynamics and intermolecular cooperativity in a class of poly(arylene ether)s are discussed. Second-order nonlinear optics is used to examine the thermal and temporal stability of chromophore orientation in the poled polymer films as a function of processing.

Fluorinated Heteroaromatic Polyethers for Low Dielectric Constant/High Temperature Applications

AbstractSynthesis and characterization of three classes of poly(arylene ether oxazole)s and poly(arylene ether thiazole)s with trifluoromethyl substituents in various positions is described. Based on these examples, the influence of the chemical structure of the polymers on properties such as glass transition temperature, solubility, and thermal stability will be discussed. Structural parameters studied are the number and nature of the heteroaromatic rings, the number and position of the trifluoromethyl groups, and the structure (flexibility, polarity) of various linking groups.

LC polyimides. XXI. Thermotropic poly(amide‐imide)s based on trimellitimides

AbstractPolycondensation of α, ω‐bis(‐4‐aminophenoxy) alkanes with trimellitic anhydride chloride (TMA‐Cl) in m‐cresol yielded a new class of poly(amideimide)s. Starting from the same diamine spacers poly(amideimides) with a more regular sequence of amide and imide groups were prepared by another synthetic method. All these poly(amide‐imide)s are semi‐crystalline and melt in the range of 250–300°C. They form a smectic‐A phase over a narrow temperature range and suffer thermal degradation at the isotropization temperature (330–350°C). The smectic‐A phase was characterized by optical microscopy (“batonnet texture”) and by synchrotron radiation measurements conducted at a heating rate of 20°C. Furthermore, it is demonstrated that slight variation of the chemical structure, such as methyl substituents or meta positions in the spacer prevent the formation of a LC phase. © 1995 John Wiley & Sons, Inc.

Synthesis and Characterization of Poly(ester-amide)s from Bis(2-oxazoline)s, Anhydrides, and Diols

A new class of poly(ester-amide)s was prepared by reacting bis(2-oxazoline)s, carboxylic anhydrides, and diols of different structures. The polymerization proceeds through the formation of a dicarboxy ester by reaction of two anhydride molecules with one diol molecule and subsequent 2-oxazoline ring opening by attack of the dicarboxy ester. The whole process leads to linear poly(ester-amide)s, whose structures were established by carbon and proton NMR analysis. The thermal characteristics of the prepared polymers were studied by DSC. Transition temperatures were found to increase with an increase in the polymer chain stiffness. Poly(ether-ester-amide)s were also prepared by employing poly(ethylene glycol) as a comonomer, alone, or in a mixture with ethylene glycol, thus obtaining block segmented polymers.