Modification of cellulose nanocrystals via surface-initiated ARGET ATRP and their reinforcement of poly(lactic acid)-based biocomposites

In order to improved the thermal stability and compatibility between cellulose nanocrystals (CNCs) and poly(lactic acid) (PLA), using activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP), customized functionalization of CNCs was achieved by surface grafting of poly(butyl acrylate) (PBA). PLA nanocomposites with different amounts of nanofillers (ranging from 1 to 5 wt%) was processed via hot-press approach. After the modification, the initial contact angle of nanocellulose increased from 50° to 120°, and the initial thermal degradation temperature increased from 150 °C to 270 °C. SEM revealed that modified CNCs were dispersed uniformly throughout the PLA matrix. The thermal characteristics of PLA composites reinforced with PBA-grafted CNCs were analyzed using DSC, demonstrating that the modified CNCs and PLA matrix had improved interactions. The compatibility of modified CNCs with the matrix was enhanced as a consequence of surface modified CNCs having better hydrophobicity and improved thermal stability. Tensile tests were used to evaluate the impact of CNCs on the mechanical characteristics, pointing an increase in the tensile strength, elongation and Young’s Modulus of roughly 350%, 100% and 120%, respectively, at 2 wt% CNC-PBA400 content.