Physical Insight into the Conditions Required in the Solid-Phase Molecular Self-Assembly of SDS Revealed by Coarse-Grained Molecular Dynamics Simulation

Effect of the Molecular Weight of Polyelectrolyte and Surfactant Chain Length on the Solid-Phase Molecular Self-Assembly

Solid-phase molecular self-assembly (SPMSA) is emerging as an efficient approach, leading to scale-span self-assembled supramolecular films. With SPMSA, freestanding macroscopic supramolecular films can be formed upon mechanically pressing the precipitates formed with polyelectrolytes and oppositely charged surfactants. Herein, we report that the film formation ability and the mechanical strength of the resultant film depend highly on the surfactant chain lengths and the molecular weight of polyelectrolytes. A coarse-grained molecular dynamics study revealed that the longer surfactant chains are beneficial for the ordered assembly of surfactant bilayers in the film, whereas the larger molecular weight of PE favors the enhanced mechanical strength of the film by promoting the long-range order of the surfactant bilayers. The current results disclosed the physical insight of the surfactant chain length and the molecular weight of polyelectrolytes into the film structure and mechanical strength, which is of practical importance in guiding the creation of SPMSA materials.

Surface Hydrophobization Provides Hygroscopic Supramolecular Plastics Based on Polysaccharides with Damage-Specific Healability and Room-Temperature Recyclability

Supramolecular materials with room-temperature healability and recyclability are highly desired because they can extend materials lifetimes and reduce resources consumption. Most approaches toward healing and recycling rely on the dynamically reversible supramolecular interactions, such as hydrogen, ionic and coordinate bonds, which are hygroscopic and vulnerable to water. The general water-induced plasticization facilitates the healing and reprocessing process but cause a troubling problem of random self-adhesion. To address this issue, here it is reported that by modifying the hygroscopic surfaces with hydrophobic alkyl chains of dodecyltrimethoxysilane (DTMS), supramolecular plastic films based on commercial raw materials of sodium alginate (SA) and cetyltrimethylammonium bromide (CTAB) display extraordinary damage-specific healability. Owing to the hydrophobic surfaces, random self-adhesion is eliminated even under humid environment. When damage occurs, the fresh surfaces with ionic groups and hydroxyl groups expose exclusively at the damaged site. Thus, damage-specific healing can be readily facilitated by water-induced plasticization. Moreover, the films display excellent room-temperature recyclability. After multiple times of reprocessing and re-modifying with DTMS, the rejuvenated films exhibit fatigueless mechanical properties. It is anticipated that this approach to damage-specific healing and room-temperature recycling based on surface hydrophobization can be applied to design various of supramolecular plastic polysaccharides materials for building sustainable societies.