Role of cellulose nanocrystals on hysteretic sorption and deformation of nanocomposites

Abstract

A molecular model of an all-cellulose nanocomposite, with an amorphous cellulose matrix reinforced by cellulose nanocrystals, is built to study the role of cellulose nanocrystal (CN) as a nanofiller in the coupled behavior between sorption and deformation. We find two competitive mechanisms. The first mechanism is the reinforcing effect through CN-matrix mechanical interaction, which constrains the sorption-induced swelling of the matrix and results in a reduction of sorption amount and of hysteresis in both sorption and deformation. The second mechanism is the CN-water interaction, enhancing water sorption in the matrix at the CN-matrix interface, increasing the sorption-induced swelling of the matrix, and increasing the resulting hysteresis in sorption and deformation. The final gain/reduction in sorption, swelling and related hysteresis depends on which of the two effects prevails. These findings shed light on the tailoring of cellulose-based composites for applications involving sorption and deformation. © 2020, Springer Nature B.V.