Impact of casting conditions on mechanical properties of polynorbornene membranes under typical biobutanol operating conditions.*

Poly(butylnorbornene)-ran-poly(hydroxyhexafluoroisopropyl norbornene) (BuNB-r-HFANB) is a promising material for biobutanol membranes with T_g’s for both segments exceeding 300^oC to provide the potential for highly stable membranes. During operation, the BuNB-r-HFANB is swollen by the aqueous butanol in the broth that impacts its properties. The membrane performance is dependent on how it is cast. Here we investigated effect of four different casting solvents (THF, Toluene, DMF and Butanol) on the mechanical properties of these membranes using DMA. The change in mechanical properties in the butanol broth was enabled by using a submersion cell with DMA. The effect of temperature in both the dry and swollen state was also examined to provide insights into how the mechanical properties of these membranes would be expected to change during operation.