Synthesis and Excimer Formation Properties of Electroactive Polyamides Incorporated with 4,5-Diphenoxypyrene Units

A new dietherpyrene-cored diamine monomer, namely, 4,5-bis(4-aminophenoxy)pyrene, was successful synthesized and formed a series of electroactive polyamides with an aryloxy linkage in a polymer main chain and bearing pyrene chromophore as a pendent group using conventional one-pot polycondensation reactions with commercial aromatic/aliphatic dicarboxylic acids. The resulting polyamides exhibited good solubility in polar organic solvents and, further, can be made into transparent films. They had appropriate levels of thermal stability with moderately high glass-transition values. The dilute NMP solutions of these polyamides exhibited pyrene characteristic fluorescence and also showed a remarkable additional excimer emission peak centered at 475 nm. Electrochemical studies of these polymer films showed that these polyamides have both p- and n-dopable states as a result of the formation of radical cations and anions of the electroactive pyrene moieties.

The effects of the inclusion of 1,2,4-triazole derivatives into the main chains of the polyurethane urea exposed to UV radiation

Linear polyurethane urea containing 1,2,4-triazole segments was obtained by polyaddition of the 3,5-diamino-1,2,4-triazole (DATA) to urethane prepolymer. Also, three crosslinked polymers with different crosslinkers (2,4,6-triaminopyrimidine (TAP), glycerin (Gly), castor oil (CO)) were synthesized. Thermogravimetric analysis, of the obtained polymers, indicated good thermal stability up to 310°C. The polyurethane urea chemical structure was confirmed by FTIR analysis. The glass transition temperatures (Tg) of these polymers, measured by differential scanning calorimetry (DSC), were found in the range of −52°C to −56°C. These values were not significantly influenced by the structure of the hard domain and the intermolecular interactions. The tensile testing showed that the inclusion of 1,2,4-triazole in polyurethane structure substantially improves the tensile strength up to 58 MPa. The obtained polyurethane urea presents surface slight hydrophobic and low interfacial tension. The positive effect of the 1,2,4-triazole segment from the polymer main chain in the UV aging process of these polymer materials has been studied. After exposure to UV radiation, few changes were observed in the molecular structure, in the surface morphology and the mechanical properties.

Synthesis of Degradable Sulfur-Containing Polymers: Precise Control of Structure and Stereochemistry

Sulfur-containing polymers refer to the polymers contain at least one sulfur atom in their repeat units of the main-chain. The incorporation of sulfur atoms into the polymer main chain endows...

Poly(para-phenylene) ionomer membranes: effect of methyl and trifluoromethyl substituents

Sulfonated poly(para-phenylene)s with high molecular weight and membrane forming capability were obtained by use of the effect of methyl and trifluoromethyl substituents. The linearity of the polymer main chain decreased...

Excellent performance of aromatic polyguanamines induced by multiple hydrogen bondable tetraazacalix[2]arene[2]-triazine ring in their main chain

Poly(guanamine)s containing tetraazacalix[2]arene[2]triazine ring within the polymer main-chain show outstanding thermal and mechanical properties arisen from the multiple-hydrogen bond.

[Rh(L-alaninate)(1,5-Cyclooctadiene)] Catalyzed Helix-Sense-Selective Polymerizations of Achiral Phenylacetylenes

The [Rh(L-alaninate)(cod)] (cod = 1,5-Cyclooctadiene) complex was synthesized and characterized. Asymmetric polymerizations of achiral phenylacetylene with two hydroxyl groups and a dodecyl group (DoDHPA) were performed by using the rhodium complex as the catalyst to provide polymers with a higher molecular weight (>105) than the polymers obtained using the [Rh(cod)Cl]2 initiator systems. The resulting polymers showed circular dichroism (CD) signals at approximately 310 and 470 nm, indicating that they have a preferential one-handed helical structure. The helix sense in the polymer main chain was controlled by the sign of the catalyst chirality. These findings suggest that the rhodium complex with a chiral amine is the true active species for the helix-sense-selective polymerization of DoDHPA. The [Rh(L-alaninate)(cod)] complex also exhibits high catalytic activity in the polymerization of phenylacetylene (PA) to give a high yield and molecular weight. All these results demonstrate that this Rh complex is an excellent catalyst for the polymerization of phenylacetylene monomers.

High Proton Conductive Sulfonated Graph Copolyimide Membranes Containing Chemically Stable Naphthalene Moieties

Syntheses, proton conductivity, gas permeability properties, and membrane stabilities of novel sulfonated graft copolyimides were investigated. The sulfonated graft copolyimide membrane showed significantly high proton conductivity (0.96 S/cm at 90°C and 98%RH, more than 6 times that of Nafion), suggesting that the protons in the sulfonated graft copolyimide membranes were efficiently transported. The oxidative stability of the novel sulfonated graft copolyimide was higher than that of the conventional graft copolyimide because of their polymer structures containing chemically stable naphthalene moieties and non–sulfonated polymer main–chain. Furthermore, the oxygen permeability of the membrane was approximately one–fourth the value of Nafion and had a very excellent gas barrier property. We demonstrated that the graft copolymer membrane could realize high proton conductivity and low gas permeability to have potential applications for use in fuel cells.