Ionic conductivity of conjugated water‐soluble rigid‐rod polymers

Abstract

Poly[(1,7‐dihydrobenzo[1,2‐d:4,5‐d′] diimidazole‐2,6‐diyl)‐2‐(2‐sulfo)‐p‐phenylene], a conjugated rigid‐rod polymer, was derivatized with pendants of propane‐sulfonated ionomers. The derivatized rigid‐rod polymer was soluble in aprotic solvents as well as in water for isotropic solutions that were processed into isotropic films. Direct‐current electrical conductivity σ of the films was measured using the four‐probe technique. Room‐temperature σ as high as 2.9 × 10−4S/cm was achieved on pristine isotropic films without using dopants. When the rigid‐rod polymer concentration exceeded 25 wt %, the isotropic solution could be transformed into a liquid‐crystalline solution that allowed deformations to be applied to produce anisotropic films. Significant increase in σ was obtained in a sheared film along both the parallel direction (∥) and the transverse direction (⊥) with a σ∥/σ⊥ = 5. Additionally, enhanced σ was realized in films heat‐treated at about 100°C, in the derivatized polymer with higher molecular weight from dialysis, and in substituting the sulfonated ion Na+ by H+ in the pendants of the polymers. Constant‐voltage measurements were applied to the polymers to monitor the σ stability for ascertaining the nature of the conductivity. No electronic contribution in σ was detected. Instead, a monotonically decreasing σ was consistently observed indicative of ionic conductivity. © 1993 John Wiley & Sons, Inc.

Crystallinity and order of poly(ethylene oxide)/lithium triflate complex confined in nanoporous membranes

“…For instance, alignment of the polymer backbones and crystalline units by stretching [22][23][24] and by magnetic fields [25] have been found to increase ionic conduction by an increased factor of 4-40-fold. Dang et al [26] have seen anisotropic ionic conduction in rigidrod, liquid-crystalline polymers while Hubbard et al [27] aligned liquid-crystalline polymer electrolytes by use of a magnetic field. Wright's group has conducted studies on the ionic conductivity of liquid crystal, smectic phase polymer electrolytes [28][29][30].…”

Structure–property relationships for a series of polyimide copolymers with sulfonated pendant groups

“…Sulfonated polyarylene-based systems (e.g., sulfonated poly(ether ether ketone), SPEEK, 2) are one of the most widely studied due to the attractive mechanical properties, as well as thermal and chemical stabilities of the parent, high temperature, thermoplastics [2]. Examples of polyarylene-based systems that have been studied for application as PEMs include poly (phenylene)s [10][11][12][13][14][15][16], poly(arylene ether)s [2,17], poly(arylene ether sulfides) [2,18,19], polyimides [20][21][22][23] and polybenzimidazoles [24][25][26][27]. In addition to the previously mentioned advantages, polyarylenes are relatively easily to functionalize and can be readily sulfonated by reagents such as concentrated sulphuric acid, fuming sulphuric acid, chlorosulfonic acid and sulphur trioxide.…”

Nanostructure, Morphology, and Properties of Fluorous Copolymers Bearing Ionic Grafts

“…Over the past decade, significant research effort has been devoted to the design of alternate membrane materials with the intention of improving properties and lowering cost. [2][3][4][5][6][7] A wide variety of different polymer systems have been examined including perfluorinated ionomers, 5,8 partially fluorinated ionomers, [9][10][11][12][13][14] polystyrene-based systems, [15][16][17][18][19][20][21][22] poly(arylene ether)s, [23][24][25][26][27][28] polyimides, [29][30][31][32][33] polybenzimidazoles, [34][35][36][37] and polyphosphazenes. [38][39][40][41] Despite this growing body of research, there exists a void in our understanding of fundamental structure-property relationships of PEMs in terms of the role of microstructure on morphology and the role of morphology on a membrane's property.…”