Photoisomerization induced scission of rod-like micelles unravelled with multiscale modeling

Effect of the Substituent Position on the Phase Behavior and Photoresponsive Dynamic Behavior of Mixed Systems of a Gemini Surfactant and trans-Methoxy Sodium Cinnamates

“…TEM observation shows (Figure a,b) that the average size of spherical micelles is approximately 40 nm, while the length of wormlike micelles exceeds several microns. The negatively charged cinnamate ions interact with the positively charged Gemini surfactant micelles by electrostatic attraction and promote the growth of micelles to some extent, − which should be the primary cause for the micellar growth. With the further addition of cinnamates, the single phase of wormlike micelles would be transformed into coexisting two phases in the macroscopic level (II, ATPS), as exhibited in Figure c.…”

“…In this study, the MCAs with different substituent positions have different properties. Among them, the centralized potential distribution, greater hydrophobicity, and smaller molecular volume of trans -OMCA – endow it with the ability to insert into the micelle barrier layer easily. , This should be the main cause why the phase diagram of 12-3-12·2Br – / trans -OMCA/H 2 O is different from that of the other two systems. By comparison, the similar diagrams of 12-3-12·2Br – / trans -MMCA/H 2 O and 12-3-12·2Br – / trans -PMCA/H 2 O should be due to the similar solvation free energies of trans -MMCA and trans -PMCA and the analogous binding energies of trans -MMCA and the Gemini surfactant with trans -PMCA and the Gemini surfactant.…”

“…Among them, the centralized potential distribution, greater hydrophobicity, and smaller molecular volume of trans-OMCA − endow it with the ability to insert into the micelle barrier layer easily. 52,53 This should be the main cause why the phase diagram of 12 From Figure 3, the potential distributions of cis-MCAs with different substituent positions are all smaller than those of trans isomers; meanwhile, the isomerization of MCAs can be excited by UV illumination. These results mean that the molecular interaction between cis isomers and surfactants is different from that of trans isomers with surfactants, providing a theoretical foundation for the photoresponsive behavior of the studied systems.…”

“…49−51 According to previous studies, the rationale of lightresponsive behavior of surfactant/cinnamate mixed systems is the trans to cis isomerization reaction of cinnamates caused by light, which profoundly affects the properties of cinnamate molecules including molar volume and amphipathicity 52 and further influences the interaction between the surfactant and photosensitizer. 53,54 Correspondingly, the rearrangement of surfactant aggregates may be induced by light illumination. Generally, the photoinduced microstructural transitions and the changes in macroscopic physicochemical properties depend on the changes in both the intermolecular interactions and the photoisomerization rate of photosensitive molecules.…”

“…This disadvantage of azobenzenes limits the development of photoresponsive self-assemblies; it is urgent to find a substitute for azobenzenes with good biocompatibility and no biotoxicity. Cinnamic acids and cinnamate esters are widely found in Arabidopsis plants and exhibit superior biocompatibility; they are regarded as suitable alternatives of azobenzenes in fabricating light-sensitive materials in recent years. − According to previous studies, the rationale of light-responsive behavior of surfactant/cinnamate mixed systems is the trans to cis isomerization reaction of cinnamates caused by light, which profoundly affects the properties of cinnamate molecules including molar volume and amphipathicity and further influences the interaction between the surfactant and photosensitizer. , Correspondingly, the rearrangement of surfactant aggregates may be induced by light illumination.…”