Synthesis,characterization, and properties of silylene–acetylene preceramic polymers

A series of silylene–acetylene preceramic polymers 3a–e were synthesized by polycondensation reaction of dilithioacetylene with dichlorosilane (H₂SiCl₂) or/and methyldichlorosilane (MeSiHCl₂). Their structures were confirmed by infrared spectra (IR), and ¹H and ²⁹Si NMR spectroscopies. Differential scanning calorimetry (DSC) diagrams show exotherms centered at 200 to 233°C temperature range, attributed to crosslinking reaction of the acetylene and Si? H groups. After thermal treatment, the obtained thermosets 4a–e possess excellent thermal stability. Thermogravimetric analysis (TGA) under nitrogen show the T_d5s (temperature of 5% weight loss) for all the thermosets are above 600°C, and the overall char yields are between 95.62% and 89.67% at 900°C. After pyrolysis at 1200°C, the obtained ceramic residues 5a–e exhibit good thermo‐oxidative stability with final weight retention between 98.76% and 91.66% at 900°C under air. In particular, perhydroploy(silylene)ethynylene 3a , which has the highest Si/C ratio in silylene–acetylene polymers, has the highest char yield, and the derived ceramic material 5a displays the best thermo‐oxidative stability. Based on Scanning electron microscopy and its associated energy‐dispersive X‐ray microanalysis (SEM EDX) and ¹³C magic angle spinning nuclear magnetic resonance (MAS NMR) analysis, ceramic 5a contains the highest SiC content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Hydropolysilanes as precursors to silicon carbide

A systematic study of the roles of three different types of monomers and their compositions in hydropolysilane homo-, co-, and terpolymers on their pyrolytic yields to silicon carbides was performed. The diorganodichlorosilane monomer, serving to increase molecular weights of the polymers, is not a significant factor in pyrolytic yields. The organotrichlorosilane monomer, leading to branched structures of the polymers, is helpful in obtaining high pyrolytic yields. The monoorganodichlorosilane monomer, providing crosslinking sites for the polymers, is useful in retarding decomposition during pyrolysis. The precursor-to-ceramic conversion chemistry was studied using thermogravimetry, infrared spectroscopy, X-ray powder diffraction, and Rutherford backscattering spectrometry. The pyrolytic yields were not pyrolysis-time-dependent but decreased as the pyrolysis temperature increased. The apparent crystalline size increased as both the pyrolysis time and temperature increased. For a 30 min pyrolysis, the pyrolysis temperature must be over 1000–1200°C to provide a crystalline pyrolytic residue. © 1995 John Wiley & Sons, Inc.     

Ferrocene-Decorated Hyperbranched Poly(aroxycarbonylphenylene)s: Synthesis, Light Refraction, Photopatterning and Precursor to Magnetic Ceramics

Ferrocene-decorated hyperbranched poly[1,3,5-tri(aroycarbonyl)phenylene]s (hb-PTACPs) are prepared in moderate yields with high molecular weights by one-pot polycyclotrimerization of 4,4′-isopropylidenediphenyl bipropiolate with 4-(ferrocenylmethyl)phenyl propiolate in reflux dimethylformamide. All the polymers are soluble and film-forming. They enjoy high thermal stability and lost little of their weight when heated to 300 °C under nitrogen. Thin solid films of the organometallic polymers shows high refractive indices (RI = 1.7038–1.6295) in the wavelength region of 400–1,700 nm. Ceramization of the organometallic hb-PTACPs at high temperature under inert atmosphere gives iron nanoparticles with high magnetizabilities. The organometallic polymers are readily crosslinked under UV irradiation and pyrolysis of the patterned polymer films produces magnetic ceramic patterns with good shape retention.     

The substituent effects on the structure and surface morphology of polyaniline

In this work, poly(2‐fluoroaniline), poly(2‐chloroaniline), poly(2‐methylaniline), and poly(N‐ethylaniline) were prepared by a self‐assembly method using an oxidizing system consisting of a dopant anion, p‐toluene sulfonate with ammonium peroxydisulfate. The effects of substituents on the surface morphology, conductivity, molecular weight, spectral and thermal properties of the polymers were studied. SEM results revealed that the surface morphology of the resulting polymers changed from nanofiber to spherical structure by changing the substituent on the aniline monomers. The structure and properties of these conducting films were characterized by FTIR, UV‐vis, elemental analysis, TGA, conductivity, and cyclic voltammetry. The polymer films show electroactivity in monomer free solution. Molecular weight of the polymers was determined by gel permeation chromatography. The dry electrical conductivity values of the substituted‐polyanilines were found to be lower than that of PANI. The results revealed that the molecular structures of the polymers were similar to those of the emeraldine form of polyaniline. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Crystalline furanic polyisocyanates

Summary 2-Furfuryl isocyanate and 2-furyl isocyanate were polymerized with several anionic initiators. Cyclic trimers and linear polymers were obtained. These products were characterized by elementary analysis, IR and ¹H-NMR spectroscopy, DSC, TGA, polarized-light microscopy, vapour-pressure osmometry and vacuum pyrolysis. The polymers possess a high degree of crystallinity. Their thermal decomposition yields the monomer and the cyclic trimer.     

Synthesis and characterization of block copolymers from aromatic diols,fumaric acid,sebacic acid and PEG

The syntheses of two linear unsaturated aromatic oligoesters, poly(hydroquinone fumarate‐co‐sebacate) (PHFS) and poly(resorcinol fumarate‐co‐sebacate) (PRFS), are described. PHFS, PRFS and poly(ethylene glycol) (PEG) are then used to prepare di‐ and tri‐block copolymers. Products thus obtained are investigated in terms of molecular weight, composition, structure and thermal properties by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and NMR and FTIR spectroscopies. A number of design parameters including the molecular weights of PHFS, PRFS and PEG and the ratios of PEG to PPFS or to PEFS are varied in order to assess their effects on product yields and properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2358–2363, 2003     

Higher‐molecular‐weight hyperbranched polyethylenes containing crosslinking structures as lubricant viscosity‐index improvers

As a new grade of polyethylene materials with unique chain architectures, hyperbranched polyethylenes synthesized by chain walking ethylene polymerization have great potential for industrial application as novel viscosity index (VI) improver in lubricant formulation. Although high‐molecular‐weight hyperbranched polyethylenes (weight‐average molecular weight of about 10⁵ g/mol) possess high shear stability, their viscosity thickening properties are compromised due to their compact chain architectures. In this work, we aim at improving their viscosity thickening property by increasing polymer molecular weight. A range of hyperbranched polymers of various enhanced molecular weights were synthesized by chain walking ethylene polymerization in the presence of small amounts of 1,4‐butanediol diacrylate as a difunctional crosslinker. The molecular weight dependences of viscosity thickening power and shear stability of these polymers containing crosslinking structures were evaluated. It is found that, with the increase of molecular weight via crosslinking, these polymers showed consistently enhanced viscosity thickening power, but with the reduced shear stability. However, their shear stability was still significantly better compared to linear polymers. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Phosphazene cyclomatrix network polymers: Some aspects of the synthesis,characterization, and flame‐retardant mechanisms of polymer

Novel phosphazene cyclomatrix network polymers were synthesized via nucleophilic displacement of activated nitro groups of tri(4‐nitrophenoxy)tri(phenoxy)cyclotriphosphazene and hexa(p‐nitrophenoxy)cyclotriphosphazene with the hydroxyls of bisphenol A. Both the monomers and polymers were characterized by Fourier transform infrared (FTIR) and ¹H‐NMR spectroscopy, and their structures were identified. The thermal and flame‐retardant properties of the polymers were investigated with thermogravimetric analysis in air, pyrolysis, and combustion experiments. Both solid and gaseous degradation products were collected in a pyrolysis process and analyzed with FTIR spectroscopy, gas chromatography/mass spectrometry, and scanning electron microscopy. The results demonstrated that the cyclomatrix phosphazene polymer would have excellent thermal stability and flame‐retardant properties if it could form a crosslinked phosphorous oxynitride structure during pyrolysis or combustion. A flame‐retardant mechanism of “intumescent” was proposed to elucidate the pyrolysis and combustion process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 880–889, 2005     

Spectrofluorometric analysis and electrical conductivities of styrene and methyl methacrylate polymers

Conductive polymers were obtained by using a new polymerization method where UV‐light was used as a photochemical initiator. To obtain high molecular weights, optimum irradiation times were determined. The luminescence properties of polymers have been found to be useful for their identification. The use of luminescence spectroscopy as an analytical technique for polymer identification involves the measurement of fluorescence emission spectrum, which is obtained by exciting the polymer with UV‐radiation. Fluorescence emission spectra of polystyrene (PS) and polymethyl methacrylate (PMMA) samples were taken at room temperature at excitation wavelengths at 290 nm and 292 nm, respectively. PPMA was prepared with different molecular weights, and the intensity of the fluorescence emission was correlated with polymer chain length. Conductivity versus molecular weight relation was established for each polymer. The plots obtained between conductivities and molecular weights can be used as a calibration curve. From the plot of emission intensity against polymer molecular weights, the molecular weights of unknown polymeric samples can be determined. The most efficient irradiation times were determined by using conductivity versus irradiation time plots. Conductivity versus temperature change of the polymeric samples at different temperatures was determined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

High‐optical transparency and low‐dielectric constant of new organosoluble polyamides containing trifluoromethyl and xanthene groups

A series of fluorinated polyamides was prepared directly by low‐temperature polycondensation of a new cardo diacid chloride, 9,9‐bis[4‐(4‐chloroformylphenoxy)phenyl]xanthene (BCPX), with various diamines containing trifluoromethyl substituents in N,N‐dimethylacetamide (DMAc). Almost all polyamides showed excellent solubility in amide‐type solvents such as DMAc and could also be dissolved in pyridine, m‐cresol, and tetrahydrofuran. These polymers had inherent viscosities between 0.77 and 1.31 dL g^?1, and their weight‐average molecular weights and number‐average molecular weights were in the range of 69,000–102,000 and 41,000–59,000, respectively. The resulting polymers showed glass transition temperatures between 240–258°C and 10% weight loss temperatures ranging from 484°C to 517°C and 410°C to 456°C in nitrogen and air, respectively, and char yields at 800°C in nitrogen higher than 55%. All polymers were amorphous and could be cast into transparent, light‐colored, and flexible films with tensile strengths of 81–100 MPa, elongations at break of 8–12%, and tensile modulus of 1.6–2.1 GPa. These polymers had low‐dielectric constants of 3.34–3.65 (100 kHz), low‐moisture absorption in the range of 0.76–1.91%, and high transparency with an ultraviolet–visible absorption cut‐off wavelength in the 322–340 nm range. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of new soluble polyamides from an unsymmetrical diamine bearing a bulky triaryl pyridine pendent group

New unsymmetrical diamine monomer containing triaryl pyridine pendent group, 2,4‐diaminophenyl [4‐(2, 6‐diphenyl‐4‐pyridyl) phenyl]ether, was synthesized via aromatic substitution reaction of 1‐chloro‐2,4‐dinitrobenzene with 4‐(2,6‐diphenyl‐4‐pyridyl) phenol, followed by Pd/C‐catalyzed hydrazine reduction. Five Polyamides (PA) were prepared by the phosphorylation polycondensation of different dicarboxylic diacids with the diamine. Inherent viscosities of PAs were in the range 0.51–0.59 g/dL indicating formation of medium molecular weight polymers. The weight and number average molecular weights of a PA, (PA‐d), determined by GPC were 6944 g/mol and 17,369 g/mol, respectively. PAs exhibited glass‐transition temperatures (T_g) in the range 140–235°C. These polymers, essentially amorphous, were soluble in polar aprotic solvents such as DMF, NMP, DMAc, DMSO, pyridine, m‐cresol, and THF. The initial decomposition temperatures (T_i) of PAs, determined by TGA in air, were in the range 300–380°C indicating their good thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

New polymer syntheses: XV. Synthesis and characterization of new polyketoamine polymers containing ether or thioether linkages in the main chain

An interesting new class of linear polyketoamine polymers containing ether or thioether linkages in the main chain has been synthesized by solution polycondensation of 4,4′‐bis(chloroacetyl)diphenyl ether ( I ), 4,4′‐bis(chloroacetyl)diphenyl sulfide ( II ) and 4,4′‐bis(chloroacetyl)diphenyl sulfone ( III ) with various aliphatic and aromatic diamines. The model compounds IV, V and VI were synthesized from the monomers I, II and III with aniline in dry benzene and their structures were confirmed by elemental and spectral analyses. The resulting polymers were characterized by elemental and spectral analyses, as well as by solubility and viscometry measurements. The thermal properties were evaluated by TGA and DSC and correlated to their structural units. X‐ray analysis showed that the polymers had some degree of crystallinity in the region 2θ = 5° to 60°. The UV‐visible spectra of some selected polymers were measured in dimethylsulfoxide (DMSO) solution and showed absorption bands in the range 260–475 nm, due to n–π* and π–π* transition. In addition, the morphological properties of selected examples were tested by SEM, and the electrical properties of these polymers were measured. Copyright © 2005 Society of Chemical Industry     

Creep rupture properties of homopolymer,copolymer, and terpolymer based on poly(oxymethylene)

Polyacetal copolymers were prepared by cationic ring‐opening copolymerizations of 1,3,5‐trioxane (TOX) with 1,3‐dioxolane (DOX), and polyacetal terpolymers were prepared by terpolymerizations of TOX, DOX, and 2‐ethylhexyl glycidyl ether (EHGE). Polyacetal polymers with three different structures such as polyacetal homopolymers, polyacetal copolymers, and polyacetal terpolymers were compared in the mechanical properties and the creep characteristics, and discussed from the view point of the polymer structure. The polyacetal copolymers and the polyacetal terpolymers were determined by ¹H‐MNR measurement. About 80 mol % of DOX and EHGE amounts in feed were incorporated randomly into the each polymer. From the plots of the degree of crystallinity (X_c) versus the tensile strength, the tensile strength and crystallintiy of the polyacetal homopoymers are higher than those of the polyacetal copolymers and the polyacetal terpolymers. However, the tensile strength does not decrease linearly with a decrease in the crystallinity among the polyacetal polymers with three different structures, the polyacetal homopolymer, the polyacetal copolymers, and the polyacetal terpolymers. Creep rupture was characterized by the activation volume, υ_c, value in Zhurkov's equation, which can be estimated from the slope in the plots of load versus log (rupture time) at 80°C. The polyacetal polymers with higher molecular weight have larger values of the activation volume than those with lower molecular weight. When the activation volume values are compared among the polyacetal polymers with the same molecular weights, they increase in the following order: the polyacetal homopolymers < the polyacetal copolymers < polyacetal terpolymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of new polyesters with methacrylate pendant groups

Summary A catalytic process for synthesis of new polyesters with methacrylate pendant groups is presented. Thus, zinc succinate catalyzed reaction of succinic anhydride with glycidyl methacrylate (GMA) in dimethoxyethane gives linear oligoesters with low molecular weights (1380-2400 Da). The polyester formation takes place via simultaneous ring opening of the cyclic anhydride and oxirane units. GMA component can be partially replaced with cyclohexeneoxide to obtain polyesters with methacrylate pendant groups in various percentages. Nearly colorless waxy polymers are obtained in excellent yields (69–97%) within 48–60 h. at 90 °C. In the study structure of the polymers have been elucidated by conventional spectroscopic techniques and photo-crosslinking of ability of their thin films have been tested by monitoring intensity of methacrylate double bonds, using IR-spectrometry methodology.     

Synthesis,characterization, thermal stability,and compatibility properties of poly(vinyl p‐nitrobenzal acetal)‐g‐polyglycidylazides

A series of energetic polymers, poly(vinyl p‐nitrobenzal acetal)‐g‐polyglycidylazides (PVPNB‐g‐GAPs), are obtained via cross‐linking reactions of poly(vinyl p‐nitrobenzal acetal) (PVPNB) with four different molecular weights polyglycidylazides (GAPs) using toluene diisocyanate as cross‐linking agent. The structures of the energetic polymers are characterized by ultraviolet visible spectra (UV‐Vis), attenuated total reflectance‐Fourier transform‐infrared spectroscopy (ATR‐FT‐IR), ¹H nuclear magnetic resonance spectrometry (¹H NMR), and ¹³C nuclear magnetic resonance spectrometry (¹³C NMR). Differential scanning calorimetry (DSC) is applied to evaluate the glass‐transition temperature of the polymers. DSC traces illustrate that PVPNB‐g?2^#GAP, PVPNB‐g?3^#GAP, and PVPNB‐g?4^#GAP have two distinct glass‐transition temperatures, whereas PVPNB‐g?1^#GAP has one. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are used to evaluate the thermal decomposition behavior of the four polymers and their compatibility with the main energetic components of TNT‐based melt‐cast explosives, such as cyclotetramethylene tetranitramine (HMX), cyclotrimethylene‐trinitramine (RDX), triaminotrinitrobenzene (TATB), and 2,4,6‐trinitrotoluene (TNT). The DTA and TGA curves obtained indicate that the polymers have excellent resistance to thermal decomposition up to 200°C. PVPNB‐g?4^#GAP also exhibits good compatibility and could be safely used with TNT, HMX, and TATB but not with RDX. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42126.     

Cyclic alkyl ketene oligomers

Two alkyl ketene oligomers (AKOs) with almost 100% purities were prepared in high yields of 80–90% from palmitic acid chloride and alkyl ketene dimer (prepared from palmitic acid chloride) in the presence of amine promoters. Two AKOs thus obtained had quite similar molecular weights (1000–10,000), carbon/hydrogen contents, X‐ray diffraction patterns, solution‐state ¹³C‐NMR spectra, and water‐contact angles. However, two AKOs had different size‐exclusion chromatograms, differential scanning calorimetric curves, FTIR spectra, and solution‐state ¹³C‐NMR spectra for ¹³C‐labeled AKOs. Based on the ¹³C‐NMR spectra of ¹³C‐unlabeled AKOs, AKOs are likely to have cyclic structures, thus having the limited molecular weights of <10,000. The results of FTIR spectra and ¹³C‐NMR spectra of ¹³C‐labeled AKOs indicated that three different repeating units were linked with various molar ratios and various connection patterns and combinations, constituting the cyclic AKOs. As a result, ¹³C‐NMR spectra of ¹³C‐labeled AKOs showed quite a number of carbon signals due to various ¹³C?O and ¹³C?C structures present in AKOs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3668–3673, 2013     

Synthesis and properties of liquid‐ crystalline triblock copolymers by ATRP,having electron‐transporting thiadiazole unit

ABA‐type block copolymers composed of 2,5‐diphenyl‐1,3,4‐thiadiazole (DPTD) oligoester and poly(methyl methacrylate) (PMMA) segments (M_n = 16 200 and 23 000) were synthesized by atom‐transfer radical polymerization and their liquid‐crystalline (LC) and photoluminescence (PL) properties were examined. The structures of block copolymers were identified by Fourier transform infrared and ¹H NMR spectroscopies. Differential scanning calorimetry measurement, polarizing microscopy observation and wide‐angle X‐ray analysis revealed that the block copolymers form thermotropic LC phase (smectic C) independent of molecular weights of PMMA segments, but a model polymer (PMMA segments having the DPTD unit in the central part) has no LC melt. Solution and solid‐state PL spectra indicated that all the block copolymers display blue emission arising from the DPTD unit. Their quantum yields are 17–21%, which increase with the PMMA chain lengths. The block copolymers have good aligned structures in the LC states, but their order parameter (S) values in sheared LC states were lower than those in the sheared LC compounds. The PL properties in the LC states were independent of the LC aligned structures. Cyclic voltammetry measurements showed that these block copolymers have deep HOMO levels compared with polymers composed of oxadiazole rings. Copyright © 2007 Society of Chemical Industry     

Synthesis,properties, and self‐assembly of poly(benzyl ether)‐b‐polystyrene dendritic–linear polymers

Poly(benzyl ether)‐b‐polystyrene dendritic–linear polymers were successfully synthesized using a dendritic chloric poly(benzyl ether) (G₁‐Cl, G₂‐Cl, and G₃‐Cl) as the macroinitiator through the atom transfer radical polymerization process. The structure and properties of the resultant polymers were characterizated by gel permeation chromatography, ¹H‐NMR, Fourier transform IR, thermogravimetric analysis, and differential scanning calorimetry. It was found that the temperature, reaction time, molar ratio of the macroinitiator to styrene, and the generation number of the macroinitiator have significant effects on the molecular weights, conversion, and polydispersities of the resulting polymers. These dendritic–linear block polymers had very good solubility in common organic solvents at room temperature. The terminal group (dendritic segments) of the polymers can affect their thermal stability. These dendritic–linear polymers after self‐assembling in selective solvents (chloroform/acetone) formed core–shell micelles. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1106–1112, 2005     

New polymer syntheses. V. Synthesis,characterization, and morphology of new conjugated polymers,copolymers, and terpolymers containing piperidone moiety in main chain

A new interesting category of polyconjugated polymer, poly(3,5‐benzylidene)isopropylpiperidone, was obtained by condensation of isopropylpiperidone with terephthalaldehyde. Copolymerization and terpolymerization with cyclopentanone and/or cyclohexanone were also carried out. The model compound was prepared by the condensation of 2 mol benzaldehyde with isopropylpiperidone; the structure was elucidated by IR, ¹H‐NMR spectra, and elemental analyses. The polymers, copolymers, and terpolymers were characterized by elemental analyses, IR, ¹H‐NMR spectra, UV and visible spectra, viscometry, and X‐ray analysis. The thermal behavior of the synthesized polymers was evaluated by TGA and DSC analyses and correlated with their structures. The morphology of terpolymer IV was examined by a scanning electron microscope. Electrical conductivities in the 10⁻⁹–10⁻¹¹ Ω⁻¹ cm⁻¹ range were observed: doping with iodine showed a small increase. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2369–2377, 1999     

Simple and versatile method for the one‐pot synthesis of segmented poly(urethane urea)s via in situ‐formed AB‐type macromonomers

We present a one‐pot method for the synthesis of poly(urethane urea)s (PUUs) with uniform (monodisperse) hard segments that eliminates tedious approaches to control the exothermic nature of isocyanate–amine reaction, is less sensitive to impurities and involves no isolation of intermediates. Reaction of two moles of hexamethylene diisocyanate with one mole of polycaprolactone of various molecular weights under optimum time and temperature led to NCO‐terminated polyurethane prepolymers. Addition of an equimolar quantity of benzoic acid and excess dimethylsulfoxide at ambient temperature produced quantitative yields of PUUs with high molecular weight. The structure of the PUUs was fully characterized using spectroscopic methods and a reasonable mechanism for the reaction sequences was determined via preparation and characterization of a model compound. Dynamic mechanical thermal analysis data confirmed the phase‐separated structure of the PUUs. Evaluation of stress‐strain curves revealed the wide‐ranging mechanical properties depending on soft‐segment molecular weight. Monitoring the remaining weight and molecular weight of polymers incubated in phosphate‐buffered saline showed hydrolytic degradability with rate depending on soft‐segment molecular weight. Also, a preliminary investigation of the interaction of L929 fibroblast cells with the prepared polymers confirmed no cytotoxicity and acceptable cytocompatibility for the PUUs. Copyright © 2010 Society of Chemical Industry