No abstract

Semi-interpenetrating polymer network (semi-IPN) membranes based on novel sulfonated polyimide (SPI) and poly (ethylene glycol) diacrylate (PEGDA) have been prepared for the fuel cell applications. SPI was synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4 0 -diaminobiphenyl 2,2 0 -disulfonic acid, and 2-bis [4-(4-aminophenoxy) phenyl] hexafluoropropane. PEGDA was polymerized in the presence of SPI to synthesize semi-IPN membranes of different ionic contents. These membranes were characterized by determining, ion exchange capacity, water uptake, water stability, proton conductivity, and thermal stability. The proton conductivity of the membranes increased with increasing PEGDA content in the order of 10 À1 S cm À1 at 908C. These interpenetrating network membranes showed higher water stability than the pure acid polyimide membrane. This study shows that semi-IPN SPI membranes based on PEGDA which gives hydrophilic group and structural stability can be available candidates comparable to Nafion 1 117 over 708C.

No abstract

A series of photoinitiator-free photosensitive polyimides (PSPIs) with lower dielectric constants have been synthesized by reaction of fluorine aromatic diamine, 2,2 0 -bis(3-amino-4-hydroxyphenyl)hexafluoropropane diamine (AHHFP) with 3,3 0 ,4,4 0 -benzophenonetetracarboxylic dianhydride (BTDA) and a mixture of various mole ratios of 3,3 0 ,4,4 0 -benzophenonetetracarboxylic dianhydride (BTDA) and 4,4 0 -(hexafluoroisopropylidene)diphthalic anhydride (6FDA) by using solution polycondensation reaction at room temperature and further imidization at 180 C. These aromatic polyimides were further acrylated via a reaction with acryloyl chlroride in the presence of triethyl amine to produce negative photoinitiator-free PSPIs. All the photoinitiator-free photosensitive polyimides were characterized by FTIR and NMR while their morphologhy was evaluated by X-ray diffractions study. These newly synthesized PSPIs were evaluated to determine their electrical, thermal, and photolithographic properties. The PSPI (AHHFP-BTDA-6FDA [1 : 0.5 : 0.5]) with high mole ratio of 6FDA showed lower dielectric constants of 2.420 at 1 kHz and 2.170 at 1 MHz in capacitance and optical methods, respectively. Further, the acrylated AHHFP-BTDA showed the highest photosensitivity than other PSPIs.

No abstract