Hong Yang

Synthesis and properties of UV-curable hyperbranched polyurethane acrylate oligomers containing carboxyl groups

Using step by step polymerization process, the first- and second-generation hyperbranched polyesters were synthesized with N,N-diethylol-3-amine methylpropionate as branched monomer and pentaerythrite as a core molecule. The second-generation hyperbranched polyurethane acrylate oligomers containing carboxyl groups were obtained by further reacting with semiadduct urethane monoacrylate and maleic anhydride. The structures of the oligomers were investigated with elemental analysis, FT–IR, and NMR. UV–Vis spectra results showed that the oligomers had sharp absorption bands at about 207xa0nm. The glass transition temperatures were investigated by differential scanning calorimetry and showed in the range of −44.96 to −19.83xa0°C. Gel permeation chromatograph was used to observe the molecular weights and polydispersities of the oligomers. UV-curing properties were characterized by FT–IR with different curing time. In addition, the solubilities and viscosity of the oligomers were also examined.

Synthesis of ternary graphene/molybdenum oxide/poly(p-phenylenediamine) nanocomposites for symmetric supercapacitors

A novel ternary graphene/molybdenum oxide/poly(p-phenylenediamine) nanocomposite (GMP) has been successfully synthesized via a two-step process including the generation of binary graphene/MoO3 composites through a hydrothermal method and chemical polymerization of p-phenylenediamine (pPD) monomer. When the feed ratio of pPD to Na2MoO4·2H2O is 1, the resulting composite (GMP-1.0) possesses superior electrochemical performance with a maximum specific capacitance of 1042.6 F g−1 at 1 A g−1 in a three-electrode system and 418.5 F g−1 at 1 A g−1 in a two-electrode system. Its energy density achieves 24.56 W h kg−1 at a power density of 325 W kg−1, and 6.8 W h kg−1 at a high power density of 3263 W kg−1. Furthermore, the ternary composite retains 86.7% of the initial capacitance after 3000 cycles, indicating its excellent cycling stability.

Hydrothermal synthesis of Ni-doped hierarchically porous carbon monoliths for hydrogen storage

Hierarchically porous carbon monoliths doped with nickel nanoparticles (Ni-HPCM) have been synthesized by hydrothermal method. The obtained Ni-HPCM materials exhibit a three dimensional interconnected macroporous network (0.5–3.5xa0μm), high specific surface area (620xa0m2/g), large pore volume (0.41xa0cm3/g), and narrow pore size distribution (3.9xa0nm). The Ni-HPCM materials present a high hydrogen storage capacity. At the pressure of 5xa0bar, the Ni-HPCM materials show a maximum hydrogen capacity of 4.29 and 1.69xa0wt% at 77 and 298xa0K, respectively. The enhanced hydrogen storage capacity is due to the hydrogen spillover effect, which allows the dissociation of hydrogen molecules on the surface of nickel nanoparticles and consequent adsorption of hydrogen atoms insidexa0the channels of HPCM material. Therefore, the Ni-doped hierarchically porous carbon monoliths in the present study are potentially suitable to be used in the range of hydrogen storage.

Magnetically-separable hierarchically porous carbon monoliths with partially graphitized structures as excellent adsorbents for dyes

Magnetically-separable hierarchically porous carbon monoliths with partially graphitized structures were synthesized through confinement self-assembly in polyurethane (PU) foam associated with a direct carbonization process from triblock copolymer F127, phenolic resol and ferric nitrate. It was observed that the magnetic Fe nanoparticles were embedded in the walls of graphitic porous carbon matrix, and the resulting materials exhibited hierarchically porous structure with macropores of 100–450xa0μm, mesopore size of 4.8xa0nm, BET surface area of 723xa0m2/g, pore volume of 0.46xa0cm3/g, and saturation magnetization of 3.1 emu/g. Using methylene blue as model dye pollutant in water, the carbon monolith materials showed high adsorption capacity of 190xa0mg/g, exhibiting excellent adsorption characteristics desirable for the application in adsorption of dyes and easy separation under an external magnetic field.

A new method to make polymers with flexible main chains and photoelectric pendants for organic semiconductors

Two novel polymers (PFMA-Ma and PFMA-Mb) were synthesized through an efficient and simple method combining conventional free radical polymerization and a Diels–Alder reaction. Different molar percentage compositions of the functionalized pendants in the polymers and two different steric configurations: endo and exo in the D–A adduct structures are revealed in 1H NMR spectra. In addition, DSC curves demonstrate that the reverse Diels–Alder reactions take place at higher temperatures (between 120 °C and 150 °C). Moreover, both of the fluorescence intensities of the two polymer films (PFMA-Ma (x = 0.700) and PFMA-Mb (x = 0.609)) become weak and even almost disappear with the increase of the annealing temperature, indicating that thermal annealing induces π–π stacking and aggregation of the pendants in the polymers. Concurrently, as the molar ratios of pendant moieties in the polymers are increased, a characteristic peak of face-to-face stacking appears in the fluorescence spectra of PFMA-Ma and a slight red-shift is observed in the fluorescence spectra of PFMA-Mb. These phenomena suggest that high molar percentage of pendants is also beneficial to their π–π stacking and aggregation. This study may provide some insights into the stacking of pendants in polymers and its influencing factors, which will be useful when these polymer materials are applied in optoelectronic devices.

Synthesis of novel poly(ester amine) dendrimers by Michael addition and acrylate esterification

Dendrimers are a new kind of polymers. They have gained widespread attentions due to their remarkable properties in recent years. In the present work, a facile and efficient synthetic approach to prepare poly(ester amine) dendrimers is presented. Three different generations of poly(ester amine) dendrimers are synthesized starting from using pentaerythritol tetraacrylate as a core, followed by Michael addition and acrylate esterification reactions. This synthetic protocol is highly efficient, high yielding, and environmentally benign. To the best of our knowledge, this is the first time that these novel poly(ester amine) dendrimers are synthesized by using Michael addition reaction as the key step. The chemical structures of these poly(ester amine) dendrimers were measured with Fourier transform infrared (FT-IR) spectroscopy, NMR, elemental analysis, gas permeation chromatography, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF). In addition, the hydroxyl value and solubilities of the poly(ester amine) dendrimers were also examined. These synthesized poly(ester amine) dendrimers, which have well-defined structures with very narrow polydispersities, can be used in many fields such as chemical engineering, medicine, and nanoengineering.