ABSTRACT For improving functional and exploitation characteristics of the poly(phenylene oxide) (PPO) gas separation membrane, it was loaded with nitrogen‐doped carbon quantum dots (CQDs) (0.5–1.5 wt%). The latter were synthesized from citric acid and L‐phenylalanine via a one‐step hydrothermal method. Both PPO and PPO/CQDs materials were studied with scanning electron microscopy; UV–vis, FTIR, and XPS spectroscopy techniques; and subjected to mechanical tests. The selectivity in the He/N 2 and O 2 /N 2 gas pair separation was shown to increase with increasing CQDs content in the PPO/CQDs membranes. Meanwhile the permeation of individual He, O 2 , and N 2 gases through the PPO/CQDs membranes decreases with increasing CQDs content since the CQDs incorporation into the PPO matrix increases the density of the films and decreases their free volume.
Borodina et al. (Sun,) studied this question.