Nacre-Mimetic Clay/Xyloglucan Bionanocomposites: A Chemical Modification Route for Hygromechanical Performance at High Humidity

作者：Kochumalayil Joby J; Morimune Seira; Nishino Takashi; Ikkala Olli; Walther Andreas; Berglund Lars A^*

来源：Biomacromolecules, 2013, 14(11): 3842-3849.

DOI：10.1021/bm400883e

Nacre-mimetic bionanocomposites of high montmorillonite (MTM) clay content, prepared from hydra. colloidal suspensions, suffer from reduced strength and stiffness at high relative humidity. We address this problem by chemical modification of xyloglucan in (XG)/MTM nacremimetic nanocomposites, by subjecting the XG to regioselective periodate oxidation of side chains to enable it to form covalent cross-links to hydroxyl groups in neighboring XG chains or to the MTM surface. The resulting materials are analyzed by FTIR spectroscopy, thermogravimetric analysis, carbohydrate analysis, calorimetry, X-ray diffraction, scanning electron microscopy, tensile tests, and oxygen barrier properties. We compare the resulting mechanical properties at low and high relative humidity. The periodate oxidation leads to a strong increase in modulus and strength of the materials. A modulus of 30 GPa for cross-linked composite at 50% relative humidity compared with 13.7 GPa for neat XG/MTM demonstrates that periodate oxidation of the XG side chains leads to crucially improved stress transfer at the XG/MTM interface, possibly through covalent bond formation. This enhanced interfacial adhesion and internal cross-linking of the matrix moreover preserves the mechanical properties at high humidity condition and leads to a Young%26apos;s modulus of 21 GPa at 90%RH.

• 出版日期2013-11