Design of Extruded\nNanostructured Composites via Decoupling\nof the Cellulose Nanofibril/Poly(butylene adipate-<i>co</i>-terephthalate) Interface

The full exploitation of the outstanding mechanical properties\nof cellulose nanofibrils (CNFs) as potential reinforcements in nanocomposite\nmaterials is limited by the poor interactions at the CNF–polymer\nmatrix interface. Within this work, tailor-made copolymers were designed\nto mediate the interface between CNFs and biodegradable poly(butylene\nadipate-<i>co</i>-terephthalate) (PBAT), and their effect\non extruded nanocomposite performance was tested. For this purpose,\ntwo well-defined amphiphilic anchor–tail diblock copolymer\nstructures were compared, with a fixed anchor block length and a large\ndifference in the hydrophobic tail block length. The aim was to evaluate\nthe impact of the copolymers’ chain length on the nanocomposite\ninterface. The presence of amphiphilic diblock copolymers significantly\nimproved the mechanical properties compared to those of PBAT nanocomposites\ncontaining unmodified CNFs. In particular, the copolymer with a longer\ntail was more effective for CNF–PBAT dispersion interactions,\nleading to a 65% increase of Young’s modulus of neat PBAT,\nwhile retaining high deformability (670%). The results provide insights\ninto the effectiveness of a waterborne third component at the CNF–matrix\ninterface and its structure–property relationship.