Significantly enhanced crystallization of poly(L-lactide) by incorporation of poly(D-lactide) grafted cellulose nanocrystals

Poly( L -lactic acid) (PLLA), as a green, biodegradable polymer material, has garnered considerable attention due to its ease of processing and exceptional properties. However, the inherent slow crystallization rate and brittleness of PLLA substantially restrict its extensive applications across various domains. In present work, PLLA and poly( D -lactide) (PDLA)-modified cellulose nanocrystals (CNCs), referred as CNC- g -L and CNC- g -D, are serving as nano-fillers to enhance the crystallization rate of PLLA. Our findings demonstrate that both nano-fillers could enhance the crystallization rate of PLLA, but the CNC- g -D shows a more efficient nucleation agent compared with its counterpart, CNC- g -L. Isothermal crystallization analysis indicates that CNC- g -D substantially increases nucleation density of PLLA, with pronounced crystallization at an elevated temperature of 155°C as confirmed by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Wide-angle x-ray diffraction (WAXD) analysis shows the preformation of stereocomplex crystals on the CNC- g -D surface may result in a fast crystallization rate. Meanwhile, after incorporation of different nano-fillers, the toughness property of PLLA has also been significantly enhanced. Our result has shown the CNC- g -D could serve as an efficient nucleation agent toward PLLA and also facilitate to aiding in establishing comprehensive structure–property relationships of polymer materials.