Polyphenylquinoxalines containing alkylenedioxy groups

A series of new polyphenylquinoxalines (PPQ) containing alkylenedioxy units within the backbone were prepared in high molecular weight forms (η_inh = 0.82–1.5 dL/g). The glass transition temperatures ranged between 203 and 241°C, decreasing with increasing length of the alkylenedioxy groups. Solution-cast films gave tensile strength, tensile modulus, and elongation at room temperature as high as 14,400 psi, 378,000 psi, and 8.1%, respectively. The PPQ were readily compression molded to provide compact tension specimens that gave fracture energy (G_Ic) as high as 10.5 in. lb/in.² Titanium to titanium tensile shear specimens provided average strengths of 4400 psi at 26°C, 3100 psi at 177°C, and 2010 psi at 203°C. The PPQ were resistant to normal aircraft fluids but were soluble in chlorinated solvents.     

Polyphenylquinoxalines: Synthesis,characterization, and mechanical properties

The synthesis of polyphenylquinoxalines (PPQ) is discussed in detail. Solutions of PPQ at 20% solids content from stoichiometric quantities of pure reactants are generally metastable, increasing in viscosity and, in some cases, gelling. This can be alleviated without any appreciable detrimental effect upon the polymer by upsetting the stoichiometry of the reactants. Relatively high molecular weight polymer (η_inh = 1.84 dl/g; H₂SO₄, 0.5%, 25°C) can be obtained when the stoichiometry is upset by 2%. Several new PPQ are reported which contain multiple phenyl ether groups located in the para position of the substituted phenyl ring. Introduction of a phenoxy group decreased T_g by 70°C. The properties of random and block copolymers of phenylquinoxaline and phenyl-as-triazine units are reported. Depending upon the processing conditions, PPQ Ti tensile shear specimens gave RT strength of 4900 psi and 316°C strength after 500 hr at 316°C of 1500 psi. Unidirectional high-modulus graphite composites provided RT flexural strength of 123,000 psi, flexural modulus of 15.6 × 10⁶ psi, and inter-laminar shear strength of 7000 psi.     

Crosslinkable poly(aryl ether ketone)s containing pendant phenylethynyl moieties: Synthesis, characterization and properties

A novel phenylethynyl-contained bisphenol monomer, (2,5-dihydroxyphenyl)(4-(2-phenylethynyl)phenyl)methanone (PEBP), has been synthesized and characterized. The resultant monomer was copolymerized with hydroquinone and 4,4′-difluorobenzophenone by means of an aromatic nucleophilic substitution reaction to provide a series of crosslinkable poly(aryl ether ketone)s containing pendant phenylethynyl moieties (PE-PAEKs). The solubility of PE-PAEKs tended to be improved with the increase in PEBP content. Wide-angle X-ray diffraction (WAXD) results showed that introduction of bulky pendant groups into molecular chains led to decrease in crystallinity. PE-PAEKs were successfully cured upon heating. Dynamic mechanical analysis (DMA) results indicated that the glass-transition temperature (T_g) of the cured PE-PAEKs was increased. Thermogravimetric analysis (TGA) results implied that the thermal stability of the cured PE-PAEKs was excellent.     

ABA triblock copolymers containing polyhedral oligomeric silsesquioxane pendant groups: synthesis and unique properties

The synthesis and characterization of POSS containing ABA triblock copolymers is reported. The use of atom transfer radical polymerization (ATRP) enabled the preparation of well-defined model copolymers possessing a rubbery poly(n-butyl acrylate)(pBA) middle segment and glassy poly(3-(3,5,7,9,11,13,15-heptaisobutyl-pentacyclo[9.5.1.1^3,9.1^5,15.1^7,13]-octasiloxane-1-yl)propyl methacrylate(p(MA-POSS)) outer segments. By tuning the relative composition and degree of polymerization (DP) of the two segments, phase separated microstructures were formed in thin films of the copolymer. Specifically, dynamic mechanical analysis and transmission electron microscopy (TEM) observations reveal that for a small molar ratio of p(MA-POSS)/pBA (DP=6/481/6) no evidence of microphase separation is evident while a large ratio (10/201/10) reveals strong microphase separation. Surprisingly, the microphase-separated material exhibits a tensile modulus larger than expected (ca. 2×10⁸ Pa) for a continuous rubber phase for temperatures between a pBA-related T_g and a softening point for the p(MA-POSS)-rich phase. Transmission electron microscopy (TEM) images with selective staining for POSS revealed the formation of a morphology consisting of pBA cylinders in a continuous p(MA-POSS) phase. Thermal studies have revealed the existence of two clear glass transitions in the microphase-separated system with strong physical aging evident for annealing temperatures near the T_g of the higher T_g phase (p(MA-POSS). The observed aging is reflected in wide-angle X-ray scattering as the strengthening of a low-angle POSS-dominated scattering peak, suggesting some level of ordering during physical aging. The T_g of the POSS-rich phase observed in the microphase separated triblock copolymer was nearly 25 °C higher than that of a POSS-homopolymer of the same molecular weight, suggesting a strong confinement-based enhancement of T_g in this system.     

Dynamic mechanical properties of polypentenamers with pendant ionic groups and their hydrogenated derivatives

Dynamic mechanical properties of substituted polypentenamers having thioglycolate side groups and their hydrogenated derivatives have been studied. Methyl esters, acids and salts were investigated at two concentrations, 5.5 mole (%) and 9.2 mole (%). In the un-hydrogenated derivatives one principal relaxation, labelled β, exists in the temperature range from-160 to 100°C. This relaxation arises from microbrownian segmental motion accompanying the glass transition. Its temperature is affected by the concentration of substituent but not the chemical nature of the substituent. A ‘rubbery plateau’ region exists in the acid and salt derivatives and in the latter the salt groups act as reinforcing fillers in this plateau region, consistent with the ionic domain model for their structures. In the hydrogenated derivatives, three relaxations occur in the temperature range from ?160 to 120°C and these are labelled α, β, and γ in order of decreasing temperature. The α relaxation arises from motions associated with the crystal phase except in the case of the 9.2 mole (%) sodium salt derivatives where it arises from motions occurring within ionic domains. The β relaxation arises from microbrownian segmental motions accompanying the glass transition, and the γ relaxation arises from localised motions which may involve both amorphous and crystalline phase components.     

Novel luminescent polymers containing backbone triphenylamine groups and pendant quinoxaline groups

Novel, conjugated polyfluorene derivatives that comprised an electron-donating triphenylamine group in the backbone and pendant, electron-accepting quinoxaline moieties, were synthesized via the Suzuki coupling reaction and their UV–vis absorption, fluorescence emission and electrochemical properties were investigated. The copolymers were readily soluble in common organic solvents and displayed good film-forming ability and excellent thermal stability. Electroluminescence devices, comprising indium tin oxide/poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid)/emitting polymer/Ba/Al, in which the polymers were employed as emissive layers, exhibited superior performance compared to that of corresponding, poly(9,9-dioctylfluorene) and poly(9,9-dioctylfluorene-co-4,4′-triphenylamine) based devices, indicating that the polymers offer promise as emissive materials in polymeric light-emitting diodes.     

Novel chemically amplified imaging materials containing malonate pendant groups

Summary A new chemically amplified polymeric imaging system based on polymers containingt-butylmalonate pendant groups has been demonstrated. Both the homopolymer of di-t-butyl (vinylbenzyl)benzylmalonate and its copolymer with styrene have been tested in coatings containing a photoacid generator. Imaging experiments confirm that the materials have very high sensitivities when exposed to UV radiation near 250nm.     

Novel polyacetylenes containing pendant 1-pyrenyl groups: synthesis, characterization, and thermal and optical properties

We report the synthesis as well as the thermal, optical and photophysical properties of four different polyacetylenes with pendant 1-pyrenyl groups: poly(1-ethynylpyrene) (PEP), poly(1-(trimethylsilanylethynyl)pyrene) (PTMSEP), poly(1-(4-(trimethylsilanyl-buta-1,3-diynyl)pyrene) (PTMSBDP) and poly(1-buta-1,3-diynylpyrene) (PBDP). Polymerizations were carried out with W and Ta catalysts, respectively, for mono- and disubstituted monomers. Soluble poly(1-ethynylpyrene) with high molecular weights (up to 4×10⁵) and extended conjugation of the main chain was obtained with good yields. Lower molecular weights (up to 6×10³) were obtained with the other polymers. Oligomers and polymers displayed high thermal stability. From the absorption spectra of the various polymers, it is found that PEP possesses a higher degree of conjugation than the other polyacetylenes. Molecular interactions occur between pyrene units present in each polymer giving rise to an emission due to associated pyrenes. These interactions are affected by the steric hindrance present in the polymer backbone. Excitation spectra combined with fluorescence decay profiles show that these interactions occur in the ground state (excited complex).     

Memory effect in polymer brushes containing pendant carbazole groups

Poly(9-(2-(4-vinyl(benzyloxy)ethyl)-9H-carbazole)) (PVBEC) brushes, have been successfully prepared on the silicon surfaces via surface-initiated atom transfer radical polymerization (ATRP). Conductance switching at a voltage of about −2.1 V is observed in the memory device based on the PVBEC brushes. The fabricated device shows the good memory characteristics as the ON/OFF current ratio up to 10⁵, and enduring 10⁶ read cycles under −1 V pulse voltages. Compared with those of the conventional Si/PVBEC/Al device fabricated by spin-coating, the switch voltage is lower and the ON/OFF current ratio is higher in the volatile Si-g-PVBEC/Al memory device.     

Crosslinking of heat-curable polybutadiene resins containing pendant acetylenic groups

Summary Copolymer of 1,3-butadiene with pendant carboxyl groups 1, was conveniently transformed into corresponding acetylenic terminal groups 2, and thermally studied. It was postulated that on heating, the polymer cures via an intermolecular cycloaddition reaction to form aromatic structures along the polymer backbone. The modified copolymer2, exhibited better thermal and thermooxidative stability and solvent resistance than the unmodified copolymer1.     

Metal catalyzed photocrosslinking of polymers containing pendant propargyl groups

Polymers containing the pendant propargyl groups can be effectively crosslinked upon UV irradiation in the presence of a small amount of W(CO)₆. The alkyne-tungsten carbonyl complex was formed initially as evident by IR spectroscopy, which was involved in the subsequent crosslinking reaction. Analyses by UV, IR, and ¹³C NMR CP/MAS spectroscopic methods confirmed the polymer crosslinking as a result of the conversion of the acetylenic units to the polyene and diacetylene moieties in the crosslinked system.     

Optical properties of block copolymers containing pendant carbazole groups and in situ synthesized CdS nanoclusters

Ultraviolet–visible absorption spectra and photoluminescence spectra were used to demonstrate efficient charge‐carrier migration in a novel bulk heterogeneous block copolymer system. One moiety of the block copolymer was functionalized with charge‐transporting carbazole groups, whereas the other block formed domains suitable for the in situ synthesis of CdS nanoclusters. The excitation of the cluster‐free copolymers with 350‐nm‐wavelength radiation led to a strong emission peak at 450 nm that was associated with the carbazole groups. When CdS clusters were present in nearby but spatially distinct domains, the carbazole emission was completely quenched and replaced by a very broad emission in the visible range (near 560 nm). The implications of these observations are discussed in the context of the energy‐transfer mechanism and possible device applications. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 177–182, 2003     

Novel polyphosphazenes containing charge-transporting agent and chromophore as pendant groups

Summary Two novel functionalized polyorganophosphazenes containing charge-transporting agent and electro-optical chromophore as side chains for the photorefractive application are synthesized. The structure characterization was carried out by ¹H-NMR, IR and UV-Visble spectra, gel permeation chromatograply and differential scanning calorimetry. Due to the good flexibility of the backbone and the high degree of functionalization, polyphosphazenes are expected to be a good candidate for photorefractive polymeric materials. Received: 13 March 2000/Revised version: 12 July 2000/Accepted: 24 July 2000     

Synthesis and properties of novel soluble fluorinated aromatic polyamides containing 4-benzoyl-2,3,5,6-tetrafluorophenoxy pendant groups

A new diaroyl chloride monomer, 5-(4-benzoyl-2,3,5,6-tetrafluorophenoxy)isophthaloyl dichloride (BTFPIPC), was prepared in a three-step synthesis. Six novel aromatic polyamides containing 4-benzoyl-2,3,5,6-tetrafluorophenoxy pendant groups were synthesized by low temperature polycondensation of BTFPIPC with six aromatic diamines in N,N-dimethylacetamide (DMAc). All these new polymers are amorphous and readily soluble in various dipolar solvents such as DMAc, N-methyl-2-pyrrolidinone (NMP), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) at room temperature. These polymers showed glass transition temperatures between 212 and 243 °C and 5% weight loss temperatures ranging from 439 °C to 456 °C. These polyamides could be cast into transparent, flexible and strong films from DMAc solution with tensile strengths of 73.5–85.4 MPa, tensile moduli of 2.06–2.72 GPa, and elongations at break of 6.4–9.3%. These new polyamide films exhibited low dielectric constants of 3.26–3.57 (1 MHz), lower water uptakes in the range of 1.27–2.28%, and excellent transparency with an ultraviolet-visible absorption cut-off wavelength in the 326–373 nm range. Primary characterization of these new polyamides shows that they might serve as new candidates for processable high-performance polymeric materials.     

Comb-branched poly(alkyl itaconates) containing pendant ethylene amine groups

Comb-branched copolymers containing ethylene amine side chains of the general structure -NH(CH₂CH₂NH)_x? H with x=1, 2, 3 and 4, were prepared by the reaction of poly(monoalkyl-codialkyl itaconate)s, using an excess of the appropriate diamine in the presence of dicyclohexylcarbo-diimide. Incorporation of ethylene amine units in the itaconate copolymers resulted in an increase in the glass transition temperature (T_g) and in the complex modulus of the modified copolymers above T_g. Both effects were proportional to the ethylene amine content of the copolymers. Chemical modification also occurred when samples were heated to about 450 K when imide formation was detected.     

Synthesis and characterization of radiation curable polyurethanes containing pendant acrylate groups

A series of radiation sensitive and relatively high molecular weight poly(tetramethylene adipate) polyurethanes containing pendant acryfate functionality was synthesized. These radiation curable materials possess good mechanical properties and behave like common thermoplastic elastomers prior to chemical crosslinking which further enhances their strength and insolublizes them. Both the precursor and the cured materials were characterized by stress-strain, differential scanning calorimetry. and dynamic mechanical testing. It was found that the poly-(tetramethylene adipate) soft segments with molecular weight of 2000 or higher were crystallizable in the cross-linked network. The soft segment molecular weight and the diisocyanate type were found to be important in determining the tensile and thermal properties of these male-rials. The crosslinking process was found to depress crystallization of the soft segments and to improve tensile properties. Increasing the soft segment molecular weight resulted in an Increased elongation al break bill a decreased ultimate stress for both the precursor linear polymers and the crosslinked materials.     

Synthesis and memory characteristics of polyimides containing noncoplanar aryl pendant groups

A series of soluble aromatic polyimides were prepared from 2,2′-diphenyl-4,4′-biphenyl diamine (DPBD), 2,2′-bis(biphenyl)-4,4′-biphenyl diamine (BBPBD), 2,2′-bis[4-(naphthalen-1-yl)phenyl]-4,4′-biphenyl diamine (BNPBD) and 2,2′-bis(3,5-dimethoxyphenyl)-4,4′-biphenyl diamine (BMPBD) by polycondensation with 2,2′-bis[4′-(3′′,4′′,5′′-trifluorophenyl)phenyl]-4,4′,5,5′-biphenyl tetracarboxylic dianhydride via a two-step procedure. The resulting polymers were fully characterized and they exhibited excellent organosolubility, high thermal and dimensional stability. Resistive switching devices with the configuration of Al/polymer/ITO were constructed from these polyimides by using conventional solution coating process. Devices with the active layer based on DPBD, BBPBD and BNPBD exhibited nonvolatile and rewritable flash type memory characteristics with the turn-on voltage at ?2.0 to ?3.0 V and the turn-off voltage at 2.0–3.0 V. Whereas, device based on BMPBD demonstrated a bipolar write-once read-many times (WORM) memory capability with the writing voltage around ±3.0 V. The ON/OFF current ratio of these devices was of about 10⁶ and the retention times can be as long as 10⁴ s.     

Chemically modified polystyrene containing pendant vinyl groups: a photosensitive polymer exhibiting chemical amplification

Soluble polystyrene, modified to contain pendant vinyl groups, was prepared in high functional yield from PStCH₂Cl or PstCHO via Wittig reactions. The polymer was used to prepare a negative-working photosensitive resist in which absorbed light initiated a free radical crosslinking chain reaction.     

UV-curable polyurethane acrylate resin containing multiple active terminal groups for enhanced mechanical properties

In this article, aiming to develop the high performance ultraviolet (UV)-curable resin used in the polymer matrix composite, a series of polyurethane acrylate (PUA) resins with the different numbers of allyl terminal groups were elaborately designed and synthesized, in which the contents of hard segments and soft segments were also adjusted simultaneously. The effects of allyl number on properties of PUA were systemically investigated. It was found that allyl number had the negligible effect on the processability as well as positive effect on thermal performances, and all PUA resins exhibited the low viscosity and rapid UV polymerization. Besides, with the change of allyl number in the range of 2–4, PUA resin casting with three allyls possessed the preferable mechanical properties such as 85.1 MPa tensile strength, 3.94 GPa tensile modulus, and 20.7 kJ m⁻² impact strength. More importantly, the high strength and high modulus of the composite further demonstrated the wide potentials of the as-prepared PUA resin as the ideal resin matrix candidate for the fiber reinforced polymer composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48147.     

化学交联胍基功能化阴离子交换膜的制备

化学交联改性是提高阴离子交换膜机械性能的有效方法。采用有机强碱五甲基胍（PMG）作为功能化试剂,对氟化聚芳醚噁二唑（FPAEO）进行了功能化反应,加入六氟双酚A（6F-BPA）进行化学交联改性处理制得交联型氟化聚芳醚噁二唑阴离子交换膜(FPAEO-AEMs)。分析结果表明：交联剂6F-BPA为6%时,溶胀率为28.8%;吸水率为86.27%;电导率达到3.12×10^-2 S·cm^-1;离子交换容量（IEC）为2.57 mequiv·g^-1;热分解温度可达280℃。