Debaditya Bera

Synthesis, characterization and gas transport properties of cardo bis(phenylphenyl)fluorene based semifluorinated poly(ether amide)s

Here we report the synthesis and properties of a series of processable poly(ether amide)s (PAs) having the bis(phenylphenyl)fluorene moiety prepared from a new diamine monomer, 9,9-bis-[3-phenyl-4-{2′-trifluoromethyl-4′-(4′′-aminophenyl) phenoxy}phenyl]fluorene. Analogous PAs having the bis(phenyl)fluorene moiety have also been prepared from the diamine 9,9-bis-[4-{2′-trifluoromethyl-4′-(4′′-aminophenyl) phenoxy} phenyl]fluorene for comparative purposes. The synthesized PAs exhibited high thermal stability (up to 517 °C and 539 °C in air and nitrogen respectively, for 10% weight loss), high glass transition temperature (272–299 °C) and high tensile strength up to 117 MPa. The optically transparent membranes (λcut-off ≥ 368 nm) from these PAs showed high gas permeability in barrer (PCO2 up to 67.42 and PO2 up to 15) and high permselectivity (PCO2/PCH4 up to 88.37 and PO2/PN2 up to 10.84); especially for the O2/N2 gas pair the PAs surpass or touch the present upper boundary limit of 2008 drawn by Robeson. The effect of the bis(phenylphenyl)fluorene moiety and diacid moieties in PAs on the dielectric values, thermal, mechanical, optical and gas transport properties were correlated.

Fluorinated Polyazoles: Synthesis, Properties, and Applications

Polyazoles are a class of high-strength heterocyclic polymers applied for different high-end applications like fibers, films, coatings, composites, ballistic-protection fabrics, and panel preparation as well as in membrane-based gas separation, pervaporation, and fuel cell applications. Polyazoles can be classified into three broad classes depending on the hetero atoms: polybenzoxazole, polybenzimidazole, and polybenzothiazole. However, their inherent insolubility in common organic solvents restricts their growth in practical applications. Incorporation of the fluorinated moiety in the polymer backbone is one of the important ways to improve the solubility and processability. This chapter deals with the detailed synthesis, properties, and membrane-based applications of these fluorinated high-performance polyazoles.

Fluorinated Polyamides: Synthesis, Properties, and Applications

Aromatic polyamides are a class of high-performance polymers. However, their insolubility and processing difficulty has restricted their applications. Fluorinated polyamides exhibit enhanced solubility in common organic solvents. Additionally, fluorinated polyamides show improved properties in comparison to the nonfluorinated analogs. This chapter describes the synthesis, properties, and applications of the fluorinated polyamides. The first part deals with the general synthetic procedure of aromatic polyamides. The structural modification and properties of the fluorinated polyamides are discussed thereafter. Finally, the use of these fluorinated polyamides in different membrane-based applications such as in gas permeation and pervaporation and as a proton exchange membrane in fuel cell application has been discussed.