Sulfonation of poly(phthalazinone ether sulfone ketone) by heterogeneous method and its potential application on proton exchange membrane (PEM)

Abstract

A series of sulfonated PPESK (SPPESKs) were synthesized through a heterogeneous sulfonation process with fuming sulfuric acid as sulfonating agent in a chloroform solvent. Membranes prepared from SPPESKs were investigated and proved to be candidates of proton exchange membrane in fuel cell operating at high temperature and low humidity. The heterogeneous sulfonation reaction is verified to first occur on the interface of the acid phase and the chloroform phase, then went on in the acid phase. SPPESKs with sulfonation degree (DS) up to 2.0 are obtained through a new reprecipitation method. Effects of reaction temperature, reaction time, acid/polymer ratio, and chloroform/polymer ratio on the sulfonation reaction are reported in details. An increase in sulfonation degree results in the increase of hydrophilicity, bringing about a substantial gain in proton conductivity. SPPESK membranes exhibit high water uptake of about 105.4% with DS of 1.01, almost two times higher than that of Nafion 1 with similar dimensional variation. Conductivity values at 358C, 60% R.H. ranging from 10 À3 to 10 À2 S/cm were measured, which are comparable to or higher than that of Nafion 1 112 (1.635 Â 10 À2 S/cm) under the same test condition. Thermogravimetric analysis shows that SPPESK membranes are stable up to 2908C in N 2 .

Novel interpenetrating polymer network sulfonated poly (phthalazinone ether sulfone ketone)/polyacrylic acid proton exchange membranes for fuel cell

“…8 three weight loss steps are observed for SPPESK membrane. Exclusive of the evaporation of water, the first weight loss peak is believed to be due to the splitting-off of sulfonic acid groups, which is confirmed by a resent report [15] and is coincidence of the weight loss calculated by different methods listed in Table 2. The second weight loss peak is associated with the evaporation of the residue solvent and the Fig.…”

“…Sulfonation of PPESK was performed according to a heterogeneous method [15]. AA was purified by under-pressure distillation.…”

“…Following literature reference [15], proton conductivity was determined using a complex impedance analyzer (Princeton Potentionstat/Galvanostat Model 283) over a frequency range of 1-10 6 Hz. SPPESK membrane of about 100 m thickness was sandwiched between two polished Cu electrodes (about 1 cm 2 area) and an AC perturbation of 5 mV was applied to the cell.…”

Electrospun nanofiber enhanced sulfonated poly (phthalazinone ether sulfone ketone) composite proton exchange membranes

“…With the increase of IEC, water uptake and swelling ratio increase in both the electrospun and the cast membranes due to the increasing number of the hydrophilic sulfonic acid group. At 80 o C, water uptake and swelling ratio increase dramatically at IEC 2.01 mmol g À 1 , which has been described in our previous work that an IEC threshold appeared at around 1.9 mmol g À 1 for water uptake and proton conductivity of SPPESK PEMs [34]. This is also typical of many other non-fluorinated PEMs [41,42].…”

“…In our previous works, sulfonated poly (phthalazinone ether sulfone ketone) (SPPESK) has been proposed as a promising PEM candidate because of its excellent thermal stability and methanol resistance [10,[32][33][34]. Recently, Ma et al attempted to electrospin pure SPPESK nanofiber, however resulted in electrospraying rather than electrospinning [35].…”