The development of morphology-controlled engineered fillers is critical for advancing high performance paper production. Herein, a mechanochemical approach was proposed to self-assemble precipitated calcium carbonate (PCC) and cellulose nanofibers (CNFs) into flexible composite fillers with tunable morphologies (granular, lamellar, and fibrous filler). By regulating the forces of composite formation, the filler morphology was precisely controlled, achieving a retention rate exceeding 90% even at 60% filler content. Notably, fibrous fillers (PCC/CNF F) exhibited superior performance, enhancing tensile and tear indices by 121.2% and 42.7%, respectively, compared to conventional PCC + CNF composites. Further optimization of fibrous filler diameter (78.7–162.5 μm) revealed that smaller diameters promoted interweaving with plant fibers, significantly improving paper tensile strength (44.65%) and opacity. This study provides a scalable strategy for designing high-content inorganic-cellulose composites, offering a breakthrough in sustainable paper engineering.
Shengjing et al. (2026) studied this question.