Free Volume Enhanced Proton Exchange Membranes from Sulfonated Triptycene Poly(Ether Ether Ketone)

Lionel C.H. Moh
Massachusetts Institute of Technology
Graduate Student

Abstract: 

Triptycene based poly(ether ether ketone) (tripPEEK) were synthesized and sulfonated to form proton exchange membranes. The increase in intrinsic free volume resulting from the incorporation of sterically bulky triptycene moiety, imparts high affinity to water at all levels of relative humidity (RH) from 10 %RH to 90 %RH. S-tripPEEK membranes showed proton conductivities of 334 mS/cm at 85 °C at 90 %RH and 0.37 mS/cm at 85 °C at 20 %RH as compared to 18.9 mS/cm and 0.0014 mS/cm observed in Nafion117TM membranes measured under the same respective conditions. Membranes of similar ion exchange capacity (IEC) are also compared to deconvolute the effect of free volume from IEC in enhancing proton conductivity. Increasing the free volume of the membranes increases the proton conductivity and decreases the activation energy for proton conduction at low humidity.

Date of Talk: 

April 13, 2017