Sulfonated Poly(arylene-co-naphthalimide)s Synthesized by Copolymerization of Primarily Sulfonated Monomer and Fluorinated Naphthalimide Dichlorides as Novel Polymers for Proton Exchange Membranes

Abstract

A novel sulfonated aromatic dichloride monomer was successfully prepared by the reaction of 2, 5-dichlorobenzophenone with fuming sulfuric acid. Copolymerization of this monomer in the form of sodium salt (1) with N-(4-chloro-2-trifluoromethylphenyl)-5-chloro-1,8-naphthalimide (2) or bis(N-(4-chloro-2-trifluoromethylphenyl)-1,4,5,8-naphthalimide (3) generated two series of novel poly(arylene-co-naphthalimide)s I-x and II-x where x represents the content of the sulfonated monomer. The synthesized copolymers with the -SO 3 H group in the side chains possessed high molecular weights revealed by their high viscosity and the formation of tough and flexible membranes. The copolymers exhibited excellent stability toward water and oxidation due to the introduction of the hydrophobic CF 3 groups. The sulfonated copolyimides that incorporated with 1,8naphthalimide (I-x) exhibited better hydrolytic and oxidative stabilities than those with 1,4,5,8-naphthalimide.Copolymer I-50 membrane endured for more than 83 h in Fenton's reagent at room temperature. The mechanical properties of I-50 membrane kept almost unchanged after immersing membrane in boiling water for 196 h. The proton conductivities of copolymer films increased with increasing IEC and temperature, reaching values above 6.8 × 10 -1 S/cm at 80 °C. Consequently, these materials proved to be promising as proton exchange membranes.

Sulfonated poly(arylene-co-imide)s as water stable proton exchange membrane materials for fuel cells

“…The films NPI(1)/SPP(50) and NPI(1)/SPP(70) had an original tensile strength of 69 and 54 MPa, respectively, which are decreased with the increasing water uptake. The similar phenomenon was observed in our previous study [24]. This phenomenon is attributed to the plastic effect of the absorbed water.…”

“…Incorporation of hydrophobic trifluoromethyl groups ortho to the imide nitrogen could protect the polymer main chains from being attacked by water molecules containing highly oxidizing radical species. The synthesis of the copolymer NPI(2)/SPP and NPI(3)/SPP have been reported in our previous paper [24]. Following the similar synthetic procedure, the novel of sulfonated poly(aryleneco-naphthalimide)s (NPI(1)/SPP(x)) were synthesized by Ni(0) catalytic coupling polymerization of NPI(1) and SPP, where x is the molar fraction of monomer SPP in the feed.…”

Poly(sulfonated phenylene)‐block‐Polyimide Copolymers for Fuel Cell Applications

“…[16] Zhang et al developed sulfonated poly(arylene-conaphthalimide)s as PEMs. [17] Their copolymers are random (statistical) ones and showed poor water stability. They modified the chemical structure of naphthalimide monomer to improve the water stability.…”

Preparation and evaluation of a proton exchange membrane based on oxidation and water stable sulfonated polyimides

“…Sulfonated polyimides (SPIs) with six-membered imide rings have been identified as one of the most promising membrane materials for PEMFC application due to their low methanol permeability, excellent thermal and mechanical stabilities, and good film forming ability [16][17][18][19][20][21][22][23]. Some of them have been claimed to display higher proton conductivity than perfluorinated materials.…”