[en] By screening uronic acid-based surfactant interfacial properties, the eﬀect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water interface has been evidenced by experimental and computational approaches. Physical and optical properties of a monolayer characterized by Langmuirﬁlmbalance, Brewster angle microscopy, and ellipsometry at 20°C reveal that the derivative of glucuronate (C14/14–GlcA) forms a more expanded monolayer, and shows a transition state under compression, in the opposite to that of galacturonate (C14/14–GalA). Both ﬁlms are very mechanically resistant (compression modulus > 300m Nm-1) and stable (collapse pressure exceeding 60mNm-1), while that of C14/14–GalA exhibits a very high compression modulus up to 600mNm-1 like ﬁlms in the solid state. Computational approaches provide single and assembly molecular models that corroborate the molecule expansion degree and interactions data from experimental results. Diﬀerences in the molecular conformation and ﬁlm behaviours of uronic acid bicatenary derivatives at the air–water interface are attributed to the intra-H-bonding formation, which is more favourable with an OH-4 in the axial (C14/14–GalA) than in the equatorial position (C14/14–GlcA).
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