Hyperbranched Polyarylenes from Copolycyclotrimerization

High molecular weight hyperbranched polyarylenes were synthesized in high yields by one-pot copolycyclotrimerizations of 2,5-diethynylthiophene (1), 4,4' -biphenyldiyne (2) and 2,7-diethynylfluorenes (3) with l-heptyne (4) and 1-dodecyne (5) using TaCl5·Ph4Sn catalysts in toluene. The structures and properties of the polymers were characterized and evaluated by 1R, NMR, TGA, UV, fluorescence and optical limiting analyses. All the polymers possess high thermal stability and emit strong blue light upon UV irradiation, whose intensities are higher than that from poly( 1 -phenyl-1 -octyne) ( PPO) , a well-known highly luminescent disubstitut-ed polyacetylene. Little aggregation-induced red shift in the photoluminescence is observed in the thin films of the polymers.

HYPERBRANCHED CONJUGATIVE MACROMOLECULES CONSTRUCTED FROM TRIPLE-BOND BUILDING BLOCKS

Polycyclotrimerization and polycoupling of acetylenic monomers respectively furnish hyperbranched polyarylenes and polyynes with high molecular weights （up to 1 × 10^6） in high yields （up to 99.9%）. The polymers possess low intrinsic viscosities and high thermal stabilities, losing little of their weights when heated to 〉 400℃. Upon pyrolysis at 〉 800℃, the polymers graphitize with high char yields （up to 86%）. Hyperbranched polyarylenes efficiently emit deep-blue to blue-green lights with fluorescence quantum yields up to 98% and strongly attenuate intense laser pulses with optical power-limiting performances superior to that of C60, a well-known optical limiter. Poly（alkenephenylenes）, poly（aroylarylenes） and polyynes are readily cross-linkable by UV irradiation, serving as excellent photoresist materials for the generation of patterns with nanometer resolution. Thin films of hyperbranched polyynes exhibit very high refractive indexes （n up to 1.86）. The internal and terminal acetylene moieties of the polyynes readily form complexes with cobalt carbonyls, which can be transformed into soft ferromagnetic ceramics with high magnetic susceptibilities （Ms up to ca. 118 emu/g） and near-zero magnetic losses.

LINEAR AND HYPERBRANCHED POLYMERS WITH HIGH THERMAL STABILITY AND LUMINESCENCE EFFICIENCY

New acetylene monomers, 6-{[(1-naphthylethynyl-4-phenyl)carbonyl]oxy}-1-phenyl-1-hexyne (1), 2,5-diethynyl-thiophene (3), and 4,4'-diethynylbiphenyl (6) were synthesized. Homopolymerization of 1 and copolycyclotrimerizations of 3 and 6 with 1-heptyne and 1-octyne have been achieved with WCl6- and TaCl5-Ph4Sn catalysts, respectively, giving soluble linear disubstituted polyacetylene (2) and hyperbranched polyarylenes (5 and 8) with high molecular weights (up to 1.2 x 10(5)) in high yields (up to 98%). The structures and properties of the polymers are characterized and evaluated by R NMR, TGA, UV, photoluminescence (PL), and electroluminescence (EL) analyses. All the polymers possess high thermal stability and emit strong blue light upon photoexcitation. The intensity of the emitted light is greater than that of poly(1-phenyl-1-octyne), a well-known highly luminescent disubstituted polyacetylene. Little aggregation-induced red shift in the PL was observed in the thin films of the polymers. By constructing a multi-layer EL device, high EL quantum yield (0.18%) has been achieved in 2, which are the best results for substituted polyacetylenes attainable so far.

SYNTHESIS AND MORPHOLOGICAL STRUCTURE OF POLY (PHENYLENE SULFIDE AMIDE)

Poly(phenylene sulfide amide) (PPSA) has been synthesized by using sulfur as S source which reacts with dichlorobenzamide (DCBA) and alkali in polar organic solvent at the atmospheric pressure. The polymer structures were determined by elemental analysis, FT-IR and H-1-NMR. It is shown that the yielded polymer has linear structure and its structure unit is -p-C6H4-CONH -p-C6H4-S-. The polymer morphology was studied by X-ray diffraction and polarized microscopy. The results show that PPSA is a crystalline polymer and its spherulites are the aggregation of nontwisting lamella or micro-thread structure. Under shearing force, these crystals are dispersed to form micro-fibrillar structure. The decomposition kinetics of PPSA was also studied at different heating rates. The decomposition energy of PPSA is higher than that of PPS.

Synthesis and Characterization of Novel Polyarylene Sulfide

A novel polyarylene sulfide, polyarylene sulfide sulfone imide, was polymerized with a new monomer （Dichlorodiimide） and sodium sulfide by taking high temperature （200℃） N-methyl-2-pyrrolidinone （NMP） as solvent. The polymer was characterized by using conventional methods. Physical properties of the polymer, including thermal stability and solubility, were also studied. DSC and TG analyses reveal that the glass transition temperature T is equal to 252.4 ℃ and that the thermal decomposition temperature Td is equal to 484.9℃.

Impact of Carbon Chain Structures in the Backbone on the Flexibility of Modified Polyarylene Sulfide Resins: Molecular Dynamics Simulations and Mesoscopic Analysis

In the domain of high-performance engineering polymers, the enhancement of mechanical flexibility in poly(phenylene sulfide) (PPS) resins has long posed a significant challenge. A novel molecular structure, designated as PP-He-IS, wherein imide rings and an aliphatic hexylene chain are covalently incorporated into the PPS backbone to enhance its flexibility, is introduced in this study. Molecular dynamics (MD) simulations are employed to systematically explore the effects of diversifying the backbone chain structures by substituting phenyl units with alkyl chains of varying lengths, referred to as PP-A-IS where “A” signifies the distinct intermediary alkyl chain configurations. Computational analyses reveal a discernable decrement in the glass transition temperature (Tg) and elastic modulus, counterbalanced by an increment in yield strength as the alkyl chain length is extended. Notably, the PP-He-IS variant is shown to exhibit superior yield strength while simultaneously maintaining reduced elastic modulus and Tg values, positioning it as an advantageous candidate for flexible PPS applications. Mesoscopic analyses further indicate that structures such as PP-He-IS, PP-Pe-IS, and PP-Bu-IS manifest remarkable flexibility, attributable to the presence of freely rotatable carbon-carbon single bonds. Experimental validation confirms that a melting temperature of 504 K which is lower than that of conventional PPS, and lower crystallinity are exhibited by PP-He-IS, thereby affording enhanced processability without compromising inherent thermal stability. Novel insights into the strategic modification of PPS for mechanical flexibility are thus furnished by this study, which also accentuates the pivotal role played by molecular dynamics simulations in spearheading high-throughput investigations in polymer material modifications.

Polyarylene Ether Nitrile and Titanium Dioxide Hybrids as Thermal Resistant Dielectrics

With the expanding application of capacitors,thermal resistant dielectric materials are in high demand due to the increasing harsh environments where the capacitors are needed and the heat generated by the capacitors.Herein,we present polyarylene ether nitrile and titanium dioxide hybrids which can be used as thermal resistant dielectrics for these capacitors.Phthalonitrile modified titanium dioxide(TiO_(2)-CN)and phthalonitrile end-capped polyarylene ether nitrile(PEN-Ph)are firstly prepared.After being cast into TiO_(2)-CN/PEN nanocomposite films,these composites self-crosslink upon heating at 320℃for 4 h,forming the polyarylene ether nitrile and titanium dioxide hybrids(TiO_(2)-PEN).Improved dielectric constants which are stable from room temperature to 200℃of these hybrids are observed,indicating the potential application of the hybrids as thermal resistant dielectrics.

PEN/BADCy Interlayer Dielectric Films with Tunable Microstructures via an Assist of Temperature for Enhanced Frequency Stability

Low dielectric in terlayer films have become an important element to ensure the development of the microelectr onics industry.A kind of flexible interlayer dielectrics,polyarylene ether nitrile/bisphenol A cyanate ester(PEN/BADCy)film,with good thermal stability and low frequency dependence,has been developed by solution casting method.Herein,materials were designed to incorporate bisphenol A cyanate ester as a part of blend,contributing to the frequency stability and structural integrity.The morphological study combined with electron microscopy revealed the uniform and flexible microstructure information with controllable morphology through self-polymerization of cyanate esters with different prepolymerization time and curing temperatures.The dielectric films could present high thermal stability with Tg>180℃.Significant improvement in the dielectric properties was achieved for the dielectric constant and loss was much stabler than neat PEN over the frequency range from 100 Hz to 5 MHz.When the prepolymerization time was 3h and final curing temperature reached 230℃,the dielectric constant and dielectric loss of the films were 3.36 and 0.013 at 100 kHz,respectively.The dimensional stability(CTE=53.67×10^-6 K^-1)was confirmed and con sidered beneficial to use as an in terlayer dielectrics.

3D confined self-assembling of QD within super-engineering block copolymers as biocompatible superparticles enabling stimulus responsive solid state fluorescence

Eliminating colloidal toxicity and enabling its intrinsic fluorescence in aggressive environmental conditions are the key challenges for commercializing hydrophobic cadmium based quantum dots(QD).Polyarylene ether nitriles(PEN)are an example of super-engineering thermoplastics that possess a unique combination of thermal stability,intrinsic fluorescence,biocompatibility and distinct emulsion self-assembly feature.Herein,the co-self-assembly of amphiphilic PEN with hydrophobic CdSe@ZnS QD,confined in the three-dimensional(3D)oil-in-water emulsion droplets,has been explored tofabricate fluorescent microparticles(FMP).It was found that these FMP demonstrated good biocompatibility(cell viability above 90%),while exhibiting a fluorescence emission in aqueous solution that was retained(intensity retention ratio above 80%)within the whole pH range of 1-14,as well as,after being subjected to autoclaving at 120℃for 1 h.Interestingly,it was discovered that introduction of calcium ions in the emulsion self-assembly contributed to in-situ generation of phase changing nanoplates inside the FMP,which led to the photo-thermal modulated solid state fluorescence from drop-casted FMP film.Thanks to their versatile fluorescence,these FMP colloids were exploited as fluorescent probes for macrophages imaging,while micro-patterns with reversible changing of emission color were induced via thermal treatment and direct laser lithography.

Sulfonated Polyarylene Ether Sulfone（SPES） and Ga2O3 Based Hybrid Polymer Electrolyte Membrane for Direct Methanol Fuel CelIs（DMFCs）

Novel hybrid polymer electrolyte membrane, based on sulfonated polyarylene ether sulfone（SPES） and Ga2O3, was prepared and characterized. The structure of the composite membrane substantially modified the properties of SPES in terms of thermal stability, mechanical properties, methanol permeability, and so on. The structure and performance of the hybrid membrane were investigated by means of Fourier transform infrared spectrophotometry（FTIR）, scanning electron microscopy（SEM）, electrochemical impedance spectroscopy（EIS）, thermal gravimetric analysis（TGA）, and water uptake（WU） test. The hybrid polymer electrolyte membrane containing a certain quantity of Ga2O3 was found to gain good proton transport characteristics, particularly at relatively high temperatures. In ad- dition, this membrane reduced methanol permeability and improved thermal stability in comparison to an unfilled reference membrane. The hybrid membrane was found suitably to be used as a polymer electrolyte membrane（PEM） in direct methanol fuel cells（DMFCs）.