Double network self-healing chitosan/dialdehyde starch-polyvinyl alcohol film for gas separation

Intrinsic self-healing materials have attracted great attention as its self-healing ability endowed by dynamic linkage. In this work, we report a double-network self-healing film which is built by Schiff base linkage between chitosan (CS) and dialdehyde starch (DS), and hydrogen bond between oxygen-containing groups in the polymer. The double-network film has been characterized by the FTIR spectra, thermal decomposition, swelling property, and morphology. The self-healing ability of (CS/DS-PVAx)n film with different concentration of PVA has been measured. The results show self-healing efficiency of (CS/DS)15 film, (CS/DS-PVA5)15 film, (CS/DS-PVA7.5)15 film and (CS/DS-PVA10)15 film is ca. 87.5%, ca.74.2%, ca. 88.4%, and ca. 75.5%, respectively. Meanwhile, the gas separation property is desirable for self-healing (CS/DS-PVAx)n films due to dense structure and amino groups in the film. According to results, (CS/DS-PVA10)15 film performed a CO2/N2 selectivity of 19.8, with ∼18 fold increment in gas selectivity as compared to (CS/DS)15 film. The combination of gas separation property and self-healing property provides a new way to improve the lifetime of gas separation films.