Electrical Conductivity Response of Poly(Phenylene-vinylene)/Zeolite Composites Exposed to Ammonium Nitrate

Poly(p-phenylenevinylene) (PPV) was chemically synthesized via the polymerization of p-xylene-bis(tetrahydrothiophenium chloride) monomer and doped with H2SO4. To improve the electrical conductivity sensitivity of the conductive polymer, Zeolites Y (Si/Al = 5.1, 30, 60, 80) were added into the conductive polymer matrix. All composite samples show definite positive responses towards NH4NO3. The electrical conductivity sensitivities of the composite sensors increase linearly with increasing Si/Al ratio: with values of 0.201, 1.37, 2.80 and 3.18, respectively. The interactions between NH4NO3 molecules and the PPV/zeolite composites with respect to the electrical conductivity sensitivity were investigated through the infrared spectroscopy

Proton Exchange Membrane Based on Sulfonated Poly (Aromatic Imide-Co-Aliphatic Imide) for Direct Methanol Fuel Cell

<div><p>A new sulfonated poly(aromatic imide-co-aliphatic imide) (SPI) for the use as a polymer electrolyte membrane was successfully synthesized from 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenylmethane-2,2'-disulfonic acid disodium salt (S-DDM), hexamethylenediamine, and 3,3',4,4'-benzophenonetetracarboxylic dianhydride in a one-step reaction. S-DDM was prepared by the direct sulfonation of DDM monomer. The degree of sulfonation of the sulfonated copolyimide was varied by using various molar concentrations of S-DDM. The sulfonated copolyimide with the highest degree of sulfonation possessed the proton conductivity of 0.0032 S.cm-1 in a wet state. The highest methanol permeability of the sulfonated copolyimide was 2.75 × 10-8 cm2.s-1 which is ~425 times lower than that of the Nafion 117. The highest membrane selectivity belonged to the membrane with 34% degree of sulfonation with the value of 1.65 × 106 s.S.cm-3 which is three orders of magnitude higher than the commercial Nafion 117.</p></div

Bis(pyrrolidene) Schiff Base Aluminum Complexes as Isoselective-Biased Initiators for the Controlled Ring-Opening Polymerization of <i>rac</i>-Lactide: Experimental and Theoretical Studies

A series of bis­(pyrrolidene) Schiff base aluminum complexes (<b>1</b>–<b>7</b>) were synthesized and characterized by NMR spectroscopy and elemental analysis. All complexes were efficient initiators for the ring-opening polymerizations of l-LA and <i>rac</i>-LA in toluene at 70 °C. Kinetic studies revealed first-order kinetics in monomer and the rates of l-LA and <i>rac</i>-LA polymerizations decreased in the order of 1,2-benzylene (<b>4</b>) ≫ 1,3-propylene (<b>2</b>) > 2,2-dimethyl-1,3-propylene (<b>3</b>) > 1,4-butylene (<b>5</b>) > <i>rac</i>-1,2-cyclohexylene (<b>7</b>) > 1,2-ethylene (<b>1</b>) ≫ 1,2-phenylene (<b>6</b>). Microstructure analyses of the resulting polylactides by homonuclear decoupled ¹H NMR spectroscopy disclosed the isotactic-biased stereocontrol of all synthesized complexes, except <b>5</b>. Isotactic stereoblock polylactide with a high <i>P</i>_m value of 0.80 was produced by <b>3</b>. A systematic DFT study on the <i>rac</i>-lactide ring-opening mechanism initiated by the initiators synthesized in this study revealed the correlation between the structure of backbone linker and the polymerization activity and stereoselectivity