Investigation on a novel photo-responsive system formed by N-methyl-N-cetylpyrrolidinium bromide and ortho-methoxycinnamic

In this work, we report a simple class of photo-responsive system that consists of cationic surfactant, N-methyl-N-cetylpyrrolidinium bromide (C16MPB), and the photoresponsive organic derivative, trans-ortho-methoxycinnamic acid (trans-OMCA). The system is studied by UV spectra, cryo-transmission electron microscopy, and rheological measurements. C16MPB and trans-OMCA in basic aqueous solution can self-assemble to form viscoelastic wormlike micelles. Upon exposure to UV light, OMCA undergoes a photoisomerization from trans to cis, which results in a change of the geometry of the C16MPB-OMCA complexes. The wormlike micelles can transform into spherical or rodlike micelles. We hope this study may enrich the understanding of photo-responsive wormlike micelles composed by cationic surfactants and photo-sensitive additives in water.