Structure and mechanical properties of transparent layered nanocomposites from LAPONITE®-hydroxyethyl cellulose vacuum-assisted self-assembly

Abstract

Transparent LAPONITE^® RD/hydroxyethyl cellulose (LRD/HEC) nanocomposite films, with a full composition range of LRD (0–100 wt%), were fabricated via a facile vacuum filtration process. The influence of the LRD content on the nanostructure and mechanical properties of the nanocomposites was systematically investigated, and there exists two critical points at a LRD content of 40 wt% and 70 wt%. In the range of 0–40 wt%, the nanocomposites showed a blurry oriented structure and the mechanical performance of the nanocomposite was improved dramatically with the increase of LRD content. In the range of 40–70 wt%, the nanocomposites showed a clearly oriented lamellar nanostructure with alternating LRD nanoplatelets and HEC layers. The mechanical properties of the nanocomposite were further enhanced at a relatively low rate with the increase of the LRD content, and reached a maximum value at a LRD content of 70 wt%. At this optimum LRD content, the nanocomposite possessed a Young’s modulus of 7.09 GPa and a tensile strength of 126.66 MPa, which are 43 times and 5.5 times higher than those of pure HEC films, respectively. Whereas when the LRD content was higher than 70%, the lamellar nanostructure was converted to tactoids with deteriorated mechanical properties. It is expected that the results herein will offer deepened understanding for the fabrication of bioinspired multilayered nanocomposites.