The impact of esterification reactions on physical properties of cellulose thin filmsElectronic supplementary information (ESI) available: Results of the characterization of the compared cellulose materials by x-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and group selective fluorescence labelling (FDAM). See DOI: 10.1039/c0sm00005a

Carboxylic acid groups introduced in cellulose by various oxidative pre-treatments (purification, dissolution) can massively influence materials' properties motivating research on counteracting conversion schemes. We used cellulose thin films to unravel the patterns of different intra- and intermolecular esterification reactions. The impact of the formation of ester bonds on the charging and swelling was studied by streaming potential/streaming current measurements and in situ ellipsometry. Methylation was found to result in a slightly reduced swelling and ion conductivity of the cellulose layers. Self-esterification reactions caused higher degrees of conversion of the carboxylic acid functionalities producing a dramatically altered swelling and ion conductivity pattern. "Carbodiimide-activated" induced self-esterification was found to be more efficient than any thermally induced conversion. Together, our study quantitatively shows the potential of self-esterification protocols for the modulation of performance-related characteristics of cellulose materials. Carboxylic acid groups in cellulose, introduced by oxidative treatments, massively influence materials' properties motivating research on counteracting conversion schemes. Using cellulose thin films we quantitatively unraveled the impact of esterification reactions on ionisation and swelling of cellulosic materials.