Nitrophenoxy groups containing polybenzimidazoles as polymer electrolytes for fuel cells: Synthesis and characterization

Abstract

Polybenzimidazoles containing different contents of pendant nitrophenoxy groups were prepared by condensation of 3,3 0 -diamino-benzidine with a mixture of 3,5-dicarboxyl-4 0 -nitro diphenyl ether and isophthalic acid (IPA) in different ratios in polyphosphoric acid. The polymers are soluble in polar aprotic solvents, they have inherent viscosities in the range of 0.75-1.10 dL g À1 and they form tough and transparent films on solution casting. They have good thermal stability with initial decomposition temperature ranging from 380 to 416 C in nitrogen, good tensile strength ranging from 56 to 65 MPa and reasonably good oxidative stability. Phosphoric acid uptake of these polymers is low compared with PBI and membranes doped with phosphoric acid exhibit good proton conductivity in the range of 6.6Â 10 À3 to 1.9Â 10 À2 S/cm at 25 C and 1.2Â 10 À2 to 4.9Â 10 À2 S/cm at 175 C, compared with 3.9Â 10 À3 S/cm at 25 C and 3.2Â 10 À2 S/cm at 175 C for PBI. These membranes are suitable for applications as polymer electrolyte for fuel cell and presumably for gas separation at high temperature.

Flexible piezoelectric sensor based on polyacrylonitrile/MWCNT/MXene composites films for human physiological health detection

“…Figure 10 displays the stress-strain curves of films; as shown in Table 1, PAN itself had a Young's modulus of 6.10 MPa, after adding 3% CNT, the Young's modulus reached 22.00 MPa, but decreased in strain, it may be that CNT led to defects inside the material, resulting in a decrease in mechanical properties [51][52][53] ; after adding 1% MXene, the strain is almost the same as the original film that without any filler and the Young's modulus increased to 9.52 MPa, it may be that the MXene and PAN have good compatibility, with the help of MXene, CNT was well distributed in PAN. 45…”

Algae infused enhancement of PBAT stiffness: Investigating the influence of algae content on mechanical and thermal properties

“…Several scholars enhanced their efforts into embedding natural fillers into polymer matrix to produce bio-composites with equivalent properties to synthetic materials. [20][21][22] These include stiffness, strength, hardness, while being sustainable, environmentally friendly, and biodegradable. Therefore, the integration of algae into polymer matrix has emerged as a promising avenue for enhancing the properties of biodegradable materials.…”

“…The usage of abundant and bio‐based material offers several sustainability advantages such as biodegradability and reduce the dependency on fossil fuels. Several scholars enhanced their efforts into embedding natural fillers into polymer matrix to produce bio‐composites with equivalent properties to synthetic materials 20–22 . These include stiffness, strength, hardness, while being sustainable, environmentally friendly, and biodegradable.…”

Enhancing the piezoelectric performance of composite PVDF flexible films through optimizing β phase content, investigating additive effects, step‐wise polarization, and thermal pressing time for energy harvesting applications

“…In the studies, different polarization techniques have been examined as an additive effect to enhance the piezoelectric properties, namely the effect on the energy harvesting. 8,9 Graphene, SiO 2 , and h-BN were investigated as potential additives to enhance the piezoelectric properties of polyvinylidene fluoride composite films. Graphene, renowned for its unique atomic structure, is particularly well-suited for micro/nano-electromechanical system actuators and sensors.…”