Poly[ethylene‐co‐(acrylic acid)]‐based nanocomposites: Thermal and mechanical properties and their structural characteristics studied by Raman spectroscopy

Nanocomposites containing carbon nanotubes (CNTs) as nanofillers and poly[ethylene‐co‐(acrylic acid)] (PEAA) or a polymer miscible mixture of PEAA and poly(2‐ethyl‐2‐oxazoline) (PEOx) as a matrix were prepared by the solution‐evaporation method with minimal damage to nanotubes. CNTs were prepared by chemical vapor deposition (CVD) with ethanol as the source of carbon. Raman spectroscopy confirmed the presence of single walled carbon nanotubes (SWNTs). High resolution transmission electron microscopy (HRTEM) showed the formation of multi walled carbon nanotubes (MWNTs). Thermal and mechanical properties of the nanocomposites were studied by analyzing samples containing different amounts of CNTs. The degree of crystallinity (X_c) of the PEAA‐based nanocomposite containing a smaller amount of CNTs was larger (X_c = 17.0%) than both the one of pure PEAA (X_c = 14.6 %) and PEAA‐based nanocomposite containing higher amounts of CNTs (X_c = 15.0%). The Young's modulus, ultimate stress, deformation at break, and toughness obtained from unidirectional tensile tests of the CNTs (1 wt%)‐PEAA nanocomposite were higher than both the one of pure PEAA and CNTs (5 wt%)‐PEAA nanocomposite. When a polymer mixture of PEAA/PEOx (containing 80 wt% of PEAA) was used as a matrix, a better mechanical response was also detected for nanocomposite containing 1 wt% CNTs. The nanocomposites containing small amounts of CNTs prepared here have potential to be used as coatings of metal or glass surfaces expecting a better mechanical performance than the one of pure matrix. POLYM. COMPOS., © 2011 Society of Plastics Engineers.     

Thermal Decomposition,Kinetics and Compatibility Studies of Poly(3‐difluoroaminomethyl‐3‐methyloxetane) (PDFAMO)

The thermal decomposition of poly(3‐difluoroaminomethyl‐3‐methyloxetane) (PDFAMO) with an average molecular weight of about 6000 was investigated using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The kinetics of thermolysis were studied by a model‐free method. The thermal decomposition of PDFAMO occurred in a two‐stage process. The first stage was mainly due to elimination of HF and had an activation energy of 110–120 kJ mol⁻¹. The second stage was due to degradation of the polymer chain. The Fourier transform infrared (FTIR) spectra of the degradation residues showed that the difluoroamino groups decomposed in a two‐step HF loss at different temperatures. The remaining monofluoroimino groups produced by the incomplete elimination of HF were responsible for the two‐stage thermolysis process. The compatibility of PDFAMO with some energetic components and inert materials used in polymer‐bonded explosives (PBXs) and solid propellants was studied by DSC. It was concluded that the binary systems of PDFAMO with cyclotrimethylenetrinitramine (RDX), 2,4,6‐trinitrotoluene (TNT), 2,4‐dinitroanisole (DNAN), pentaerythritol tetranitrate (PETN), ammonium perchlorate (AP), aluminum powder (Al), aluminum oxide (Al₂O₃) and 1,3‐diethyl‐1,3‐diphenyl urea (C₁) were compatible, whereas the systems of PDFAMO with lead carbonate (PbCO₃) and 2‐nitrodiphenylamine (NDPA) were slightly sensitized. The systems with cyclotetramethylenetetranitroamine (HMX), hexanitrohexaazaisowurtzitane (CL‐20), 3‐nitro‐1,2,4‐triazol‐5‐one (NTO), ammonium nitrate (AN), magnesium powder (Mg), boron powder (B), carbon black (C. B.), diphenylamine (DPA), and p‐nitro‐N‐methylamine (PNMA) were incompatible. The results of compatibility studies fully supported the suggested thermal decomposition mechanism of PDFAMO.     

Synthesis,cationic polymerization and curing reaction with epoxy resin of 3,9‐di(p‐methoxybenzyl)‐1,5,7,11‐tetra‐oxaspiro(5,5)undecane

A new spiro ortho carbonate, 3,9‐di(p‐methoxybenzyl)‐1,5,7,11‐tetra‐oxaspiro(5,5)undecane was prepared by the reaction of 2‐methoxybenzyl‐1,3‐propanediol with di(n‐butyl)tin oxide, following with carbon disulfide. Its cationic polymerization was carried out in dichloromethane using BF₃‐OEt₂ as catalyst. The [¹H], [¹³C]NMR and IR data as well as elementary analysis of the polymers obtained indicated that it underwent double ring‐opening polymerization. The polymerization mechanism is discussed. The curing reaction of bisphenol A type epoxy resin in the presence of the monomer and a curing agent was investigated. DSC measurements were used to follow the curing process. In the case of boron trifluoride‐o‐phenylenediamine (BF₃‐OPDA) as curing agent, two peaks were found on the DSC curves, one of which was attributed to the polymerization of the epoxy group, and the other to the copolymerization of the monomer with the isolated epoxy groups or homopolymerization. However, when BF₃‐H₂NEt was used as curing agent, only one peak was present. IR measurement of the modified epoxy resin with various weight ratios of epoxy resin/monomer was performed in the presence of BF₃‐H₂NEt as curing agent. The results demonstrate that the conversion of epoxy group increases as the content of monomer increases. The curing process and the structure of the epoxy resin network are discussed. © 2000 Society of Chemical Industry     

Highly Diastereoselective Synthesis of 2,6‐Di[1‐(2‐alkylaziridin‐1‐yl)alkyl]pyridines,Useful Ligands in Palladium‐Catalyzed Asymmetric Allylic Alkylation

C₂‐Symmetrical, enantiopure 2,6‐di[1‐(1‐aziridinyl)alkyl]pyridines (DIAZAPs) were prepared by a high‐yielding, three‐step sequence starting from 2,6‐pyridinedicarbaldehyde and (S)‐valinol or (S)‐phenylglycinol. The new compounds were tested as ligands in palladium‐catalyzed allylation of carbanions in different solvents. Almost quantitative yield and up to 99 % enantiomeric excess were obtained in the reactions of the enolates derived from malonate, phenyl‐ and benzylmalonate dimethyl esters with 1,3‐diphenyl‐2‐propenyl ethyl carbonate.     

Synthesis and characterization of alternate copolymers constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments

1,3‐Dichloro‐1,1,3,3‐tetraphenyldisilazane (DCTPS) with 71.6% yield was synthesized by the reaction of hexaphenylcyclotrisilazane (HPCT) with Ph₂SiCl₂ catalyzed by dibutyltin dilaurate. A ring‐closure reaction of DCTPS was carried out with BuLi in xylene–hexane mixture solvent; 1,3‐bis(chlorodiphenylsilyl)‐2,2,4,4‐tetraphenyl‐cyclodisilazane (BcPTPC) with 73.2% yield was obtained. Hydrolysis of BcPTPC in ether–triethylamine solvent resulted in 71.9% yield of 1,3‐bis(diphenylhydroxysilyl)‐2,2,4,4‐tetraphenylcyclodisilazane (B_HPTPC). By condensation polymerization of B_HPTPC with α,ω‐bis(diethylamino)‐oligo‐dimethylsiloxane, a kind of alternate copolymer constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments [P(BPTPC‐alt‐ODMS)] was synthesized. BcPTPC, B_HPTPC as well as P(BPTPC‐alt‐ODMS) were characterized by ²⁹Si‐NMR spectra, FT‐IR spectra, and elemental analysis. DGA study shows that P(BPTPC‐alt‐ODMS)s are thermally stable. The thermal decomposition onsets of P(BPTPC‐alt‐ODMS)s are all above 520°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1484–1490, 2005     

Synthesis and Characterization of 1,5‐Dinitro‐2,6‐bis(trinitromethyl)‐3a,4a,7a,8a‐tetrahydro‐[1,4]dioxino[2,3‐d:5,6‐d′]diimidazole (DNTNDI)

The polynitro imidazole derivative 1,5‐dinitro‐2,6‐bis(trinitromethyl)‐3a,4a,7a,8a‐tetrahydro‐[1,4]dioxino[2,3‐d:5,6‐d′]diimidazole (DNTNDI) was synthesized through nitration of 2‐(dinitromethylene)‐1H‐imidazol‐4‐ol in HNO₃/Ac₂O followed by cyclization of the di‐enol. It was characterized by NMR, IR, elemental analysis, and single‐crystal X‐ray diffraction analysis. Compound DNTNDI crystallizes in the orthorhombic space group P2(1)2(1)2(1). The thermal decomposition was studied with thermogravimetry/derivative thermogravimetry (TG/DTG) in a nitrogen atmosphere with a heating rate of 5 K min⁻¹. The TG/DTG analysis indicated that DNTNDI has 97.64 % mass loss between 127 °C and 173 °C by undergoing exothermic decomposition. The density of DNTNDI was determined as 1.906 g cm⁻³ at 293 K with an Ultrapycno 1000 Pycnometer. The denotation velocity and denotation pressure of DNTNDI were calculated as 9325 m s⁻¹ and 40 GPa by applying the LOTUSES (version 1.4) code, respectively. The oxygen balance of DNTNDI is 0 and its oxygen content amounts to 51.78 %, which is superior to that of new generation of chlorine‐free oxidizer ammonium dinitramide (ADN).     

Poly(ethylene‐graft‐ethylene oxide) (PE‐PEO) and poly(ethylene‐co‐acrylic acid) (PEAA) as compatibilizers in blends of LDPE and polyamide‐6

In a blend of two immiscible polymers a controlled morphology can be obtained by adding a block or graft copolymer as compatibilizer. In the present work blends of low‐density polyethylene (PE) and polyamide‐6 (PA‐6) were prepared by melt mixing the polymers in a co‐rotating, intermeshing twin‐screw extruder. Poly(ethylene‐graft‐polyethylene oxide) (PE‐PEO), synthesized from poly(ethylene‐co‐acrylic acid) (PEAA) (backbone) and poly(ethylene oxide) monomethyl ether (MPEO) (grafts), was added as compatibilizer. As a comparison, the unmodified backbone polymer, PEAA, was used. The morphology of the blends was studied by scanning electron microscopy (SEM). Melting and crystallization behavior of the blends was investigated by differential scanning calorimetry (DSC) and mechanical properties by tensile testing. The compatibilizing mechanisms were different for the two copolymers, and generated two different blend morphologies. Addition of PE‐PEO gave a material with small, well‐dispersed PA‐spheres having good adhesion to the PE matrix, whereas PEAA generated a morphology characterized by small PA‐spheres agglomerated to larger structures. Both compatibilized PE/PA blends had much improved mechanical properties compared with the uncompatibilized blend, with elongation at break (ε_b) increasing up to 200%. Addition of compatibilizer to the PE/PA blends stabilized the morphology towards coalescence and significantly reduced the size of the dispersed phase domains, from an average diameter of 20 μm in the unmodified PE/PA blend to approximately 1 μm in the compatibilized blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2416–2424, 2000     

Poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)– poly(dimethylsiloxane) block copolymers

The hydrolytic condensation of 1,3‐dichloro‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane under neutral conditions produced α'ω‐dihydroxy‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane (polymerization degree ≈ 4). The homofunctional condensation of α'ω‐dihydroxy‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane in a toluene solution and in the presence of activated carbon was performed, and dihydroxy‐containing oligomers with various degrees of condensation were obtained. Through the heterofunctional condensation of dihydroxy‐containing oligomers with α'ω‐dichlorodimethylsiloxanes in the presence of amines, corresponding block copolymers were obtained. Gel permeation chromatography, differential scanning calorimetry, thermomechanical analysis, thermogravimetry, and wide‐angle roentgenography investigations were carried out. Differential scanning calorimetry and roentgenography studies of the block copolymers showed that their properties were determined by the ratio of the lengths of the flexible and linear poly(dimethylsiloxane) and rigid poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane) fragments in the macromolecular chain. At definite values of the lengths of the flexible and rigid fragments, a microheterogeneous structure was observed in the synthesized block copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1409–1417, 2002; DOI 10.1002/app.10335     

Alternating copolymerization and terpolymerization of vinyl‐substituted phenolic antioxidants with propene and carbon monoxide by a palladium(II)‐based catalyst: polyketones containing intramolecular stabilizers

The copolymerization and terpolymerization reactions of the vinyl‐substituted phenolic stabilizers, 6‐tert‐butyl‐2‐(1,1‐dimethylhept‐6‐enyl)‐4‐methylphenol, o‐allylphenol, 4‐methylstyrene‐2,6‐di‐tert‐butylphenol and 2,6‐di‐tert‐butyl‐4‐allylphenol, with propene and carbon monoxide, by using the solvent‐stabilized palladium(II ) phosphine complex [Pd(dppp)(NCCH₃)₂](BF₄)₂ (dppp, 1,3‐bis(diphenylphosphino)propane) as a catalyst precursor and methanol as a co‐catalyst, is described. The influence of functional α‐olefins/CO units, distributed statistically along the propene/carbon monoxide (P/CO) copolymer backbone, on the molecular weight, glass transition temperature (T_g), elastic behavior and stability of the high‐molecular‐weight P/CO copolymer has been investigated. Loss of both elasticity and transparency were observed upon incorporating o‐allylphenol as a termonomer. The terpolymers, which contain phenolic stabilizers, were shown to be more stable when compared to the stabilizer‐free polyketones. In contrast to the propene/carbon monoxide copolymer, no degradation was observed for the 2,6‐di‐tert‐butyl‐4‐allylphenol/P/CO terpolymer; instead, the molar masses increased. Copyright © 2004 Society of Chemical Industry     

Poly(1,2‐diaminobenzene) and poly(1,3‐diaminobenzene): Synthesis,characterization, and properties

Poly(1,2‐diaminobenzene) (1,2‐DAB) and poly(1,3‐diaminobenzene) (1,3‐DAB) have been synthesized by using ammonium persulfate as oxidizing agent in the presence and in the absence of the following metal ion salts: CuCl₂, NiCl₂, and CoCl₂ with different HCl concentrations. The products showed a different content of the metal ion depending on the HCl concentration. The polymers were characterized by Fourier transform infrared (FTIR), ultraviolet‐visible (UV‐Vis) spectroscopy, thermal analysis, and electrical conductivity. The polymerization yield depended on the presence of metal ions that can react as oxidizing reagents and/or catalysts. The polymerization mechanism depended on the position of the substituent. For poly(1,2‐DAB) a ladder‐type structure was obtained, and for poly(1,3‐DAB) one similar to that of polyaniline. The thermal stability increased as the metal ion content in the polymer matrix increased. The electrical conductivity of the polymer did not depend on the metal ion content in the polymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2564–2572, 2002     

New low bandgap conjugated polymer derived from 2, 7‐carbazole and 5, 6‐bis(octyloxy)‐4, 7‐di(thiophen‐2‐yl) benzothiadiazole: Synthesis and photovoltaic properties

To develop conjugated polymers with low bandgap, deep HOMO level, and good solubility, a new conjugated alternating copolymer PC‐DODTBT based on N‐9′‐heptadecanyl‐2,7‐carbazole and 5, 6‐bis(octyloxy)‐4,7‐di(thiophen‐2‐yl)benzothiadiazole was synthesized by Suzuki cross‐coupling polymerization reaction. The polymer reveals excellent solubility and thermal stability with the decomposition temperature (5% weight loss) of 327°C. The HOMO level of PC‐DODTBT is ‐5.11 eV, indicating that the polymer has relatively deep HOMO level. The hole mobility of PC‐DODTBT as deduced from SCLC method was found to be 2.03 × 10^?4 cm²/Versus Polymer solar cells (PSCs) based on the blends of PC‐DODTBT and [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) with a weight ratio of 1:2.5 were fabricated. Under AM 1.5 (AM, air mass), 100 mW/cm^?2 illumination, the devices were found to exhibit an open‐circuit voltage (V_oc) of 0.73 V, short‐circuit current density (J_sc) of 5.63 mA/cm^?2, and a power conversion efficiency (PCE) of 1.44%. This photovoltaic performance indicates that the copolymer is promising for polymer solar cells applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrochromic properties of a copolymer of 1‐4‐di[2,5‐di(2‐thienyl)‐1H‐1‐pyrrolyl]benzene with EDOT

Homopolymer of 1‐4‐di[2,5‐di(2‐thienyl)‐1H‐1‐pyrrolyl]benzene and its copolymer with 3,4‐ethylenedioxythiophene (EDOT) were electrochemically synthesized and characterized. Resulting homopolymer and copolymer films have distinct electrochromic properties. At the neutral state, homopolymer has λ_max due to the π‐π* transition as 410 nm and E_g was calculated as 2.03 eV. The resultant copolymer revealed multichromism through the entire visible region, displaying red‐violet, brownish yellow green, and blue colors with the variation of the applied potential. For the copolymer, λ_max and E_g were found to be 450 nm and 1.66 eV, respectively. Double potential step chronoamperometry experiment shows that homopolymer and copolymer films have good stability, fast switching times, and high optical contrast in NIR region as 41 and 30%, respectively. Copolymerization with EDOT not only decreases the band gap, E_g, but also enhances the electrochromic properties. Hence, electrochemical copolymerization is considered to be a powerful tool to improve the electrochromic properties of N‐substituted 2,5‐di(2‐thienylpyrrole) derivatives. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Vapor Pressures,Mass Spectra and Thermal Decomposition Processes of Bis(2,2‐Dintropropyl)acetal (BDNPA) and Bis(2,2‐Dinitropropyl)formal (BDNPF)

Simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and Fourier‐transform ion cyclotron resonance (FTICR) instruments have been used to measure the mass spectra, measure vapor pressures and evaluate the thermal decomposition mechanism of bis(2,2‐dinitropropyl)acetal (BDNPA) and bis(2,2‐dinitropropyl)formal (BDNPF). The high mass accuracy FTICR mass spectra provide the chemical formulas of the ion fragments formed in the mass spectra of BDNPA, BDNPF and their decomposition products, and provide a basis for predicting possible structures of the ion fragments. The heat of vaporization (Δ_vapH) and vapor pressure at 25 °C are 93.01±0.38 kJ/mol and 1.4532+0.40/−0.27 mPa for BDNPA, and 84.77±0.88 kJ/mol and 2.20+1.87/−1.07 mPa for BDNPF. STMBMS data support a nitro‐nitrite ( NO₂→ O NO) rearrangement mechanism for both compounds. Upon rearrangement, both NO and NO₂ are cleaved from the structure, thus producing a ketone radical. The nitro‐nitrite rearrangement begins to occur at appreciable rates between 160 and 180 °C. Additional decomposition products include amines, imines and amides, as well as CO₂ and H₂O at higher temperatures. STMBMS mass loss data suggest the formation of a residue during the decomposition of BDNPA and BDNPF. The major difference between the decomposition of the two compounds is the slower reaction rate of BDNPF. We postulate that the less sterically hindered formal carbon of BDNPF subjects it to interactions with an intermediate, thus forming a complex and delaying its release. Methods to elucidate complex thermal decomposition mechanisms from STMBMS data are illustrated.     

Synthesis and Characterization of New Aromatic Polyamides with N,N′‐Di(4‐n‐alkylphenyl)benzodiimide Unit on the Main Chain

Summary: New aromatic polyamides containing two n‐alkylphenylimide units fused to the main chain were prepared by the activated polyamidation of 3,6‐di(4‐carboxyphenyl)‐N,N′‐di(4‐n‐alkylphenyl)pyromellitimides ( C _m DA , m = 0, 8, 12, 16) with oxy‐4,4′‐dianiline in a mixture of N‐methylpyrrolidone and pyridine (Py) in the presence of triphenyl phosphite and CaCl₂. The imide‐containing dicarboxylic acid monomers were synthesized by the imidization of 3,6‐di(4‐carboxyphenyl)pyromellitic dianhydride with 4‐n‐alkylanilines. The polymers showed both enhanced thermal stability and excellent solubility due to the presence of thermally stable pendent imido groups and internally plasticizing n‐alkyl chains. Their glass transition temperatures were between 225 and 285 °C and decreased with increasing side chain length. Wide‐angle X‐ray diffraction investigations revealed that all the polymers are amorphous and have typical layered structures formed by n‐alkyl side chains.

     

Synthesis and Characterization of Poly(3‐azidomethyl‐3‐methyl oxetane) by the Azidation of Poly(3‐mesyloxymethyl‐3‐methyl oxetane)

Poly(3‐azidomethyl‐3‐methyl oxetane) (PAMMO) was prepared by the azidation reaction of poly(3‐mesyloxymethyl‐3‐methyl oxetane) (PMMMO), which was synthesized by cationic ring‐opening polymerization of MMMO for the first time. Two azidation reaction methods of PMMMO were considered to obtain PAMMO securely and efficiently. The thermal decomposition performance of PAMMO was studied by TG/FTIR/MS. The result of TG showed that the thermal decomposition of PAMMO involved two steps. Combined with FT‐IR and MS of the escaping gases to investigate the decomposition products of PAMMO, it is found that the first step was mainly corresponding to the thermal decomposition of azide group ( N₃), and the second step was mainly corresponding to the thermal decomposition of the polyether backbone.     

The Synthesis of Energetic Compound on 4,4′‐((2,4,6‐trinitro‐1,3‐phenylene)bis(oxy)) bis(1,3‐dinitrobenzene)(ZXC‐5): Thermally Stable Explosive with Outstanding Properties

The novel, thermally stable explosive 4,4′‐((2,4,6‐trinitro‐1,3‐phenylene)bis(oxy))bis(1,3‐dinitrobenzene) (Be referred to as ZXC‐ 5 in our laboratory) has been reported. ZXC‐5 can be synthesized by a simple synthetic method (The total synthesis of ZXC‐ 5 requires only two steps and the total yield of ZXC‐ 5 is more than 89 %) and shows the superior detonation performances (detonation pressure, detonation velocity, sensitivity toward mechanical stimuli, and temperature of decomposition). The structure of ZXC‐5 was characterized by multinuclear (¹H, ¹³C) NMR and mass spectrometry. The structure in the crystalline state was confirmed by low‐temperature single‐crystal X‐ray diffraction. From the calculated standard molar enthalpy of formation and the measured densities, the detonation properties were predicted by using the EXPLO5 V6.01 thermochemical computer code. The sensitivity of ZXC‐ 5 towards impact, electrostatic discharge, and friction were also measured.     

Synthesis,Crystal Structure,and Thermal Behaviors of 3‐Nitro‐1,5‐bis(4,4′‐dimethylazide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP)

The energetic material, 3‐nitro‐1,5‐bis(4,4′‐dimethyl azide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP), was firstly synthesized by means of Click Chemistry using 1,5‐diazido‐3‐nitrazapentane as main material. The structure of NDTAP was confirmed by IR, ¹H NMR, and ¹³C NMR spectroscopy; mass spectrometry, and elemental analysis. The crystal structure of NDTAP was determined by X‐ray diffraction. It belongs to monoclinic system, space group C2/c with crystal parameters a=1.7285(8) nm, b=0.6061(3) nm, c=1.6712(8) nm, β=104.846(8)°, V=1.6924(13) nm³, Z=8, μ=0.109 mm⁻¹, F(000)=752, and D_c=1.422 g cm⁻³. The thermal behavior and non‐isothermal decomposition kinetics of NDTAP were studied with DSC and TG‐DTG methods. The self‐accelerating decomposition temperature and critical temperature of thermal explosion are 195.5 and 208.2 °C, respectively. NDTAP presents good thermal stability and is insensitive.     

Synthesis of 1‐Amino‐3‐(trimethylsilyl)allenes by Organocuprate Addition to 3‐(Trimethylsilyl)propyne Iminium Salts

1‐Dialkylamino‐3‐(trimethylsilyl)allenes 2a—q were obtained by conjugate addition of alkyl, vinyl, aryl, hetaryl, and silyl groups, via the respective organocuprates, to 3‐(trimethylsilyl)propyne iminium triflates 1a—d . Similarly, 2‐vinylidene‐2,3‐dihydro‐1,3‐benzothiazoles 4a,b were synthesized from semicyclic propyne iminium triflates 3a,b and a di‐tert‐butyl cuprate.     

Fabrication and optical characterization of poly(2,5‐di‐n‐butoxyphenylene) nanofibril arrays

Anodic aluminum oxide (AAO) membrane can be used as template for the synthesized nanostructures. In this article, we have prepared the AAO membrane by using electrooxidation of aluminum substrate in phosphoric acid, and fabricated poly(2,5‐di‐n‐butoxyphenylene) (BuO–PPP) nanofibril arrays by oxidative coupling polymerization of 1,4‐di‐n‐butoxybenzene (DBB) within the pores of the AAO template membrane. The detailed molecular structure of the polymer nanofibrils was characterized by using infrared and ¹H nuclear magnetic resonance spectra, and estimated to consist of almost equal fractions of 1,4‐ and 1,3‐ linkages. We have used transmission electron microscopy, scanning electron microscopy, and atom force microscopy to confirm the morphologies and images of the AAO template membrane and the fabricated nanometer scale of BuO–PPP nanofibril arrays. The experimental results demonstrated that the pores of the AAO membrane were regular and uniform, and parallel each other, and the BuO–PPP chains in the narrowest template‐synthesized nanofibrils were oriented parallel to the porous axes of the AAO membrane and perpendicular to the surface of the aluminum substrate. The polymer chain orientation was partially responsible for the enhanced conductivity. The ultraviolet absorption spectrum of the BuO–PPP nanofibril arrays shown that the polymer contains a better extended π‐conjugation system along poly‐(p‐phenylene) backbone, which resulted in longer wavelength shift of the absorption band, the absorption maxima were located at 258 nm (E₁ absorption band) and 332 nm (E₂ absorption band), respectively. Photoluminescence spectrum of the BuO–PPP nanofibril arrays exhibited a blue emission. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 425–430, 2004     

Synthesis,characterization and conformational transitions in copolymers of 2‐(o‐chlorophenyl)‐4‐methylene‐1,3‐dioxolane with vinyl monomers

Copolymers of 2‐(o‐chlorophenyl)‐4‐methylene‐1,3‐dioxolane with methyl methacrylate and styrene were synthesized in benzene at 85 °C in the presence of 2,2′‐azobisisobutyronitrile as initiator. The structure of the resulting copolymers was investigated and a polymerization mechanism was proposed. The intrinsic viscosity of the copolymers in dilute solutions of carbon tetrachloride was determined as a function of temperature and conformational transitions were investigated. Copyright © 2004 Society of Chemical Industry