Coexistence of aggregates and flat states of hydrophobically modified sodium alginate at an oil/water interface: A molecular dynamics study.

Hydrophobically modified sodium alginate stabilizes benzene in water emulsions. The stability of the emulsion is related to the interface properties at the mesoscopic scale, but the details of the polymer adsorption, conformation and organization at oil/water interfaces at the microscopic scale remain largely elusive. In this study, hydrophobically modified sodium alginate was used as a representative of amphiphilic polymers for prediction of distribution of HMSA at the oil/water interface by coarse-grained molecular dynamics simulation. The result showed that driven by the interaction energy between the hydrophobic segment and benzene, HMSA will actively accumulate at the oil/water interface. The HMSA molecules parallel to the oil/water interface prevent the hydrophobic segments in the micelles from approaching the oil/water interface, so that the micelles can exist stably by steric hindrance. This study would be helpful to understand the aggregation behavior of amphiphilic polymers at the oil/water interface, these results can have applications in diverse sectors such as drug, food industry, where polymers are used to stabilize emulsions.

Highly stretchable and tough alginate-based cyclodextrin/Azo-polyacrylamide interpenetrating network hydrogel with self-healing properties.

Most structural self-healing materials were developed based on either reversible supramolecular interaction or dynamic covalent bonding. It seems a good idea to incorporate self-healing properties into high-performance materials. In this study, we fabricated the alginate-based cyclodextrin and polyacrylamide azobenzene highly stretchable and tough interpenetrating composite hydrogel with self-repairing behavior under light irradiation. Initially, the alginate-based cyclodextrin and polyacrylamide azobenzene were designed and synthesized. The corresponding structural, thermal, and morphological properties of hydrogels were characterized. The reversible transformation of the sol-gel can be achieved by the irradiation upon ultraviolet light and visible light. The self-healing behavior of this composited gel is based on the host-guest interaction between cyclodextrin and azobenzene. The recovery gel elongation at 48 h healing in the dark condition was is 0.04 MPa, with an elongation of 1140 %. Therefore, this gel can achieve self-healing ability while maintaining highly stretchable and tough performance.