High loading capacity of Fe3 + cations in LBL films made from poly(ethyleneimine) and tannic acid: An alternative to coordination driven multistep assembly using polyphenols and Fe3 +

•Step-by-step deposition of tannic acid and poly(ethyleneimine)•The obtained films display high loading affinity for Fe3 + and Cu2 + cations.•The Fe3 + loading is uniform across the film.•The Fe3 +/tannic acid stoichiometry is estimated.

Thin films incorporating tannic acid and Fe3 + ions appear as a versatile method to coat almost all surfaces in a one pot reaction or in a step-by-step manner. Both kinds of films display different optical properties and the films deposited in a step-by-step manner are more impermeable for FITC labeled dextran than the one pot deposited equivalents. Herein, tannic acid is deposited in a step by-step manner with poly(ethyleneimine) to yield linearly growing films able to incorporate Fe3 + cations in an irreversible manner and in an amount which is proportional to the film thickness. The stoichiometry of iron/tannic acid in the film was found to be close to 10 when the films were incubated with Fe(NO3)3. 9 H2O at 2.48 × 10− 3 mol·L− 1. This exceptional loading capacity may be exploited for environmental purposes. Cu2 + cations can also be loaded in the films.

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