Multilamellar spherical micelles of alkali lignin: dissipative particle dynamics simulations

Lignin has an immense potential for the production of lignin-based functional materials. In this work, effect of 2-chloro-ethyltrimethyl ammonium chloride (AC)-grafted alkali lignin (AL) on the morphologies in water was investigated by dissipative particle dynamics (DPD) simulations. The results showed that AL molecules formed spherical micelles, but the corresponding phenylpropane units of AL were randomly distributed in spherical micelles. However, AC-grafted modification of phenolic hydroxyl groups in AL led to the formation of multilamellar spherical micelles. The formation of multilamellar spherical micelles of AL mainly went through four stages: small clusters, larger aggregates with a core-shell structure, trilaminar, and multilamellar spherical micelles. AL molecules resulted in dimethomorph molecules being randomly distributed in the spherical micelle, while the dimethomorph molecules were perfectly entrapped into the spherical micelles of AC-grafted AL. Various molecular weights of AL had no effect on the formation and size of multilamellar spherical micelles. With increasing the content of AC-grafted AL, small clusters, multilamellar spherical micelles, tube-like, and lamellar aggregates were observed successively. This work highlights the potential of lignin to prepare monodispersed lignin-based functional colloidal spheres.

Coarse-grained beads were performed energy minimization, geometric optimization, NPT ensemble (298 K and 1.0 bar), and NVT ensemble (298 K) calculations. DPD simulations were carried out at 300,000 steps in a 30×30×30 Rc³ cubic box with Materials Studio 7.0 program.