Efficient and Size-Controllable Method and Mechanism for Preparing Cellulose Nanospheres

Cellulose nanosphere (CNS), reported as a novel cellulose material, has encountered significant challenges in achieving efficient and size-controllable preparation, which has considerably constrained its development. In this study, we have developed an innovative and size-controllable method that synthesizes CNS within only 7 min. A detailed investigation into the morphology, chemical structure, and crystalline structure of CNS was conducted, leading to the proposal of a formation mechanism for CNS. The mechanism is described as follows: cellulose dissolution, hydrophobic triethoxymethylsilane hydrolysis, condensation nucleation in supersaturation, growth through hydrogen-bonding interactions and condensation, and CNS forms in the critical supersaturation. The supersaturation level was controlled by adjusting the stirring speed, thus realizing the size-controllable preparation of CNS and verifying the proposed mechanism. The results demonstrate that the particle size of CNS increases from 63.4 ± 14.0 nm to 108.6 ± 27.1 nm as the stirring speed decreases from 1000 r/min to 300 r/min.