Natural aging of multilayer films containing hydrophobically modified poly(acrylate)s or their complexes with surfactants

The paper reports the natural aging of polyelectrolyte multilayers containing sodium hydrophobically modified poly(acrylates) (PACnNa, n = 10 and 18) or complexes of PACnNa with alkyltrimethylammonium bromides (CxTAB, x = 10, 12, 14, 18) and poly(diallyldimethylammonium chloride) (PDADMAC). Wettability, thickness and surface morphology of aged multilayers are compared with those of freshly made. Contact angle (CA) increases with the alkyl chain length of the PACnNa and of the CxTAB in the complex with PACnNa. Wettability measurements unveil that only five bilayers of alternatively deposited PAC18Na-C18TAB and PDADMAC reach in 12 months the same CA as sixty freshly prepared bilayers. The PDADMAC outer layer gives higher CA and root mean square roughness than the negatively terminated multilayers. The results are significant for gaining new insight into the underlying mechanism of multilayers aging, saving materials, and improving the surface coatings for long term preservation.