Cellulose nanofibrils surfaces were functionalized for the design of poly(<sub>L</sub>-lactide) (PLLA)-nucleating surfaces. PLLA is one of the most widely used biodegradable polymers. However, a major drawback of PLLA is its low heat resistance. Although the crystallization of PLLA itself is a simple and effective way to solve the problem, the crystallization rate of PLLA is very low. Therefore, in this study, the nucleating ability of the surface functionalized cellulose nanofibrils were investigated to widen the application range of PLLA. Cellulose nanofibrils with a width of ~3 nm were obtained from wood cellulose via the oxidation using 2,2,6,6-tetramethylpiperidiniyl-1-oxyl as a catalyst and successive mechanical treatment. The surface carboxyl groups of the nanofibrils were selectively modified with amine-terminated poly(ethylene glycol) chains, via simple ionic bonds. The isothermal and non-isothermal crystallization kinetics of the PLLA in the composites were studied using differential scanning calorimetry and polarized optical microscopy. The surface functionalized cellulose nanofibril/PLLA nanocomposite films were successfully prepared using a solvent casting method with chloroform. With the aid of the surface modification, the nanofibrils, which have extraordinary large specific surface areas, were individually dispersed in the PLLA matrix. As a result, the nanofibrils efficiently increased the nucleation rate of the PLLA on the surfaces. After isothermal crystallization for 5 minutes, the thermal expansion values were more than 10 times lower than neat PLLA films, because of the increased degree of crystallization of the PLLA in the nanocomposite. Therefore, the surface functionalized cellulose nanofibrils showed nucleating ability for PLLA, and effectively improved the thermomechanical properties.

Functionalization of cellulose nanofibril surfaces to enhance crystallization and mechanical properties of poly-l-lactide

249th National Meeting (2015)

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