A monotonic increase in CO2 permeance as a function of reaction temperature for a fixed reaction time of 1 h could be observed (Figure ). An average increase in permeance from 1091 GPU to 2444 GPU was observed when the temperature increased from 85 to 90 ºC. The average CO2/N2 selectivity increased from 20.2 to 22.8, respectively. This favorable increase in CO2 permeance, as well as CO2/N2 selectivity, can be attributed to a higher density of O clusters achieved at an elevated reaction temperature, given that cluster nucleation follows an energy barrier and is consistent with the literature on millimeter-scale PG membranes. Increasing the epoxidation time to 3 h at 85 ºC led to a further increase in CO2 permeance of 2850 GPU with CO2/N2 selectivity of 19.3.