Preparation and characterization of crosslinked sulfonated poly(ether ether ketone) membranes using 4-vinylbenzyl chloride via electron beam irradiation and subsequent Friedel-Craft reaction

Synthesis of 4,4′‐Diacryloylphenyl Ether to Conveniently Crosslink Sulfonated Poly(ether ether ketone) Membranes via Electron Beam Irradiation

“…DAPE is expected to crosslink polymer chains via radical process. We proposed one of possible mechanisms for crosslinking SPEEK with 4‐vinylbenzyl chloride on electron beam irradiation . A similar mechanism may also occur in this system.…”

“…The experimentally measured IEC value of the SPEEK membrane (1.69 mmol/g) is very close to the theoretical value (1.71 mmol/g), whereas the experimental IEC values of all the c‐SPEEK membranes were smaller than their corresponding calculated values, as listed in Table . Perhaps, this discrepancy resulted from incomplete ion exchange between SO 3 H groups in the c‐SPEEK membranes and NaCl dissolved in the aqueous solution, probably because it may be more difficult for Na + ions to diffuse into SO 3 H groups for ion exchange within the more highly crosslinked membranes …”

“…The lowered degradation temperatures may be because of the unreacted or partially reacted DAPE. If some polymer chains had been cleaved into shorter chains during the electron beam irradiation process, the resulting small polymer molecules would also contribute to the slightly decreased thermal stability of the c‐SPEEK membranes …”

“…The methanol permeabilities of the membranes were measured in an aqueous 3.0 M methanol solution at 35 °C, following the reported procedure . The methanol permeability of the original SPEEK membrane (2.8 × 10 −6 cm 2 /s) was close to that of Nafion 212, because of the high content of the sulfonic acid group.…”

“…Gel fraction, ion‐exchange capacity (IEC), dimensional stability, water uptake, proton conductivity, and methanol permeability of polymer membranes were determined following the reported procedures . The thermal and mechanical properties were also measured following the reported procedures, using a Q‐50 thermogravimetric analyzer (TA instruments, New Castle, DE, USA) and an INSTRON Series IX Universal Testing System Model 4400 (Instron Co. Norwood, MA, USA), respectively.…”