Synthesis and properties of novel sulfonated (co)polyimides bearing sulfonated aromatic pendant groups for PEFC applications

Novel sulfonated diamines bearing aromatic pendant groups, namely, 3,5‐diamino‐3′‐sulfo‐4′‐(4‐sulfophenoxy) benzophenone (DASSPB) and 3,5‐diamino‐3′‐sulfo‐4′‐(2,4‐disulfophenoxy) benzophenone (DASDSPB), were successfully synthesized. Novel side‐chain‐type sulfonated (co)polyimides (SPIs) were synthesized from these two diamines, 1,4,5,8‐naphthalene tetracarboxylic dianhydride (NTDA) and nonsulfonated diamines such as 4,4′‐bis(3‐aminophenoxy) phenyl sulfone (BAPPS). Tough and transparent membranes of SPIs with ion exchange capacity of 1.5–2.9 meq g^?1 were prepared. They showed good solubility and high thermal stability up to 300 °C. They showed isotropic membrane swelling in water, which was different from the main‐chain‐type and sulfoalkoxy‐based side‐chain‐type SPIs. The relative humidity (RH) and temperature dependence of proton conductivity were examined. At low RH, the novel SPI membranes showed much higher conductivity than the sulfoalkoxy‐based SPIs. They showed comparable or even higher proton conductivity than Nafion 112 in water at 60 °C (>0.10 S cm^?1). The membrane of NTDA‐DASDSPB/BAPPS (1/1)‐s displayed reasonably high proton conductivities of 0.05 and 0.30 S cm^?1 at 50 and 100% RH, respectively, at 120 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2862–2872, 2006     

A chiral [(dipyridylphosphine)RuCl2(1,3-diphenylpropanediamine)] catalyst for the hydrogenation of aromatic ketones

The use of chiral 1,3-diphenylpropanediamine in combination with Ru-Xyl-P-Phos, gave up to 95% ee in the hydrogenation of acetophenone.     

Enhanced dehumidification performance of PVA membranes by tuning the water state through incorporating organophosphorus acid

A novel thin film composite membrane with superior propylene dehumidification performance was prepared by coating a high hydrophilic organophosphorus acid ethylene diamine tetra(methylene phosphonic acid) (EDTMPA) doped poly(vinyl alcohol) (PVA) on polysulfone (PS) hollow fiber membranes. Experimental studies and molecular dynamics simulations were combined to probe the existing states and the transport mechanism of water in the membranes. Water vapor sorption experiments revealed that the enhanced dehumidification performance was governed by the diffusion process. Water states and water distribution were investigated by molecular dynamics simulation. At low EDTMPA content (<10 wt.%), states of the water were not obviously changed and the increase of water diffusion coefficient was mainly attributed to enlarged free volume of the membrane. At high EDTMPA content (10–30 wt.%), the increase in the water diffusion coefficient mainly arose from the variations in the water states. Strong interaction between PVA and EDTMPA reduced the amount of water that bounded to the PVA and increased the proportion of free water. The diffusion coefficients of water increased with increasing proportion of free water, since the mobility of free water was higher than that of bound water. The permeance of water reached 997.7 GPU for the PVA–EDTMPA/PS membrane with a 20 wt.% EDTMPA content when the proportion of free water was the highest, and the separation factor increased to infinity.     

A comparative study of reactivity and selectivity of chiral diamines and structurally analogous amino alcohol ligands in enantioselective alkylations with diethylzinc

A series of chiral δ‐diamines and structurally analogous δ‐amino alcohols derived from natural tartaric acid were synthesized and a comparative study of their activity and selectivity in the enantioselective alkylation of aromatic aldehydes was carried out. Our results show that in general the δ‐diamines were found to be better chiral inducers than the corresponding δ‐amino alcohols. The highest selectivity was observed when benzaldehyde was alkylated in the presence of the benzylic diamine, giving (R)‐1‐phenylpropanol with an ee of 42%. Copyright © 2008 John Wiley & Sons, Ltd.     

Preparation of novel axially chiral NHC–Pd(II) complexes and their application in oxidative kinetic resolution of secondary alcohols

Novel axially chiral N‐heterocyclic carbene (NHC) Pd(II) complexes were prepared from optically active 1,1′‐binaphthalenyl‐2,2′‐diamine (BINAM) and H₈‐BINAM and their crystal structures were unambiguously determined by X‐ray diffraction. These chiral N‐heterocyclic carbene (NHC) Pd(II) complexes were applied in the oxidative kinetic resolution of secondary alcohols using molecular oxygen as a terminal oxidant or under aerobic conditions, affording the corresponding sec‐alcohols in good yields with moderate to good enantioselectivities. Copyright © 2009 John Wiley & Sons, Ltd.     

Polyaddition of bis(seven‐membered cyclic carbonate) with diamines: A novel and efficient synthetic method for polyhydroxyurethanes

This article deals with the polyaddition of a novel bis(seven‐membered cyclic carbonate), 1,2‐bis[3‐(1,3‐dioxepan‐2‐one‐5‐yl)‐propylthio]ethane, with the diamines 4,9‐dioxa‐1,12‐dodecanediamine and p‐xylylenediamine. The polyaddition was carried out at 30–70 °C for 6–24 h in dimethyl sulfoxide to obtain the corresponding polyhydroxyurethanes with number‐average molecular weights of 10,900–35,700 in good yields. The reaction of a monofunctional seven‐membered cyclic carbonate, 5‐allyl‐1,3‐dioxepan‐2‐one (7CC), with monoamines was also carried out to examine the reactivity in comparison with that of six‐ and five‐membered cyclic carbonates. The reaction rate constants of 7CC with n‐hexylamine and benzylamine were estimated to be 48.5 and 11.0 L/mol · h, respectively, in dimethyl sulfoxide‐d₆ (initial reagent concentration = 1 M) at 30 °C. The seven‐membered cyclic carbonate ring was 2.98 and 5.82 kcal/mol more strained than those of the six‐ and five‐membered cyclic carbonates, respectively, according to a semiempirical molecular orbital calculation with the PM3 Hamiltonian. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4091–4100, 2001     

淀粉接枝丙烯酸甲酯与乙二胺合成高分子螯合剂

以淀粉为原料,接枝丙烯酸甲酯,然后与乙二胺反应,合成了具有多个酰胺基和胺基的螯合淀粉(SMAEN)。接枝淀粉(SMA)的接枝率(GP)和接枝效率(GE)分别为44.14%和18.42%。由凯式定氮法测得此螯合淀粉的含氮量为2.86%。红外光谱分析结果表明,淀粉已经成功地被接枝和螯合。将螯合淀粉用于对铜离子和银离子的吸附,结果表明,对铜离子和银离子的吸附量分别为:3.328和1.667 mmol/g。     

树枝状多氨基环氧树脂固化剂的合成及其固化行为

树枝状多氨基环氧树脂固化剂的合成及其固化行为;树枝状大分子;丙烯酸酯双键;乙二胺(EDA)     

An optimized preparation of bismaleimide–diamine co‐polymer matrices

The main aim of this study was to develop an improved method for the preparation of a bismaleimide–diamine (BMI/DDM) polymer matrix, achieving shorter curing time, longer processing time (pot life), and good thermal mechanical properties. A matrix of BMI/DDM thermoset was prepared at optimal conditions and formulation, containing BMI and DDM in a 2:1 mol ratio with 0.1 wt% of dicumyl peroxide (DCP) as the curing accelerator. An optimal temperature of 150°C was selected for both melt‐mixing and curing processes. The mechanism of matrix preparation was also investigated using differential scanning calorimetry and quantitative Fourier transformed infrared analysis. DCP at the optimal concentration was found to accelerate cross‐linking reactions between BMI and DDM without inhibiting the chain‐extension reaction of BMI. The specified formulation exhibited longer gel time (208 s/g) and shorter post‐curing time (2 h) compared to other formulations. In addition, thermomechanical behavior and thermal stability were analyzed by dynamic mechanical analysis and thermomechanical analysis, and thermogravimetric analysis, respectively. The storage modulus (E′), glass transition temperature (T_g), and decomposition temperature (T_d) of the BMI/DDM thermosets increased with the BMI content of the formulations, while the coefficient of thermal expansion and damping behavior (tan δ) decreased in a similar manner, primarily because of an increase in the degree of cross‐linking. Copyright © 2014 John Wiley & Sons, Ltd.     

Investigation on thermal conductivity and physical properties of polythiophene/p-phenylenediamine-graphene oxide and polythiophene-co-poly(methyl methacrylate)/p-phenylenediamine graphene oxide composites

An efficient approach was employed to simultaneously functionalize and reduce the graphene oxide (GO) with p-phenylene diamine (PPD) using simple refluxing. There was a possibility of nucleophilic substitution of amino moieties of PPD with the epoxy groups of GO. The polythiophene (PTh) and polythiophene-co-poly(methylmethacrylate) (PTh-co-PMMA) nanocomposites with chemically modified GO were prepared using in situ polymerization technique. Two series of nanocomposites that is PTh/PPD-GO and PTh-co-PMMA/PPD-GO were designed. The nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, scanning electron microscopy (SEM), thermal conductivity, and electrical conductivity measurement. The FTIR spectra depicted the characteristic absorption peaks for the formation of copolymer and their composites with PPD-GO. The SEM micrographs showed that the PPD-GO nanosheets were homogeneously dispersed in copolymer matrix forming nano-granular morphology. The nanofluids were prepared by suspending modified GO particles inside the basefluid of polythiophene and PTh-co-PMMA. The thermal conductivity of nanocomposites was significantly improved even with low PPD-GO loading. The thermal conductivity of PTh-co-PMMA/PPD-GO with 1.5 wt.% filler was increased to 1.42 W/mK at a higher temperature. The XRD patterns confirmed the presence of chemical interactions between the copolymer and filler particles. The electrical conductivity of PTh-co-PMMA/PPD-GO was also found to increase in the range of 6.1 × 10^?3–2.5 × 10^?2 S/cm. Novel PTh-co-PMMA/PPD-GO-based nanocomposite is potentially significant in high-performance thermal systems.