Rheology on novel UV–light irradiation thinning and thickening viscoelastic oleamidopropyl dimethylamine/<i>trans</i>-<i>o</i>-methoxycinnamic acid micelle systems

Abstract For the enrichment of photosensitive micelle systems, several novel types of UV light viscoelastic photosensitive micelle systems were prepared by compounding oleamidopropyl dimethylamine (PKO–O) and trans - o -methoxy-cinnamic acid ( trans -OMCA). The flow curves and viscoelastic properties of the micelle systems were investigated before and after UV irradiation at a wavelength of 365 nm. The concentration of PKO–O was controlled at 1.0 wt% and 2.0 wt%, with a fixed molar ratio (MR) of PKO–O to trans -OMCA of 1:0.75, after exposure to UV light, the zero shear viscosity ( η 0 ) of the optimal micellar system decreased by more than 99 %. Furthermore, when the mass concentration of PKO–O ranged from 3.0 wt% to 5.0 wt%, while maintaining the same molar ratio, the optimal micelle system achieved a more than 15-fold increase in η 0 . These phenomena are attributed to the isomerization of trans -OMCA to cis -OMCA under UV light irradiation. The Carreau-Yasuda model effectively describes the flow curves of the PKO–O/OMCA micelle systems. The viscoelastic response of the micelle systems can be well characterized by the Maxwell model. Furthermore, the four-parameter rheokinetic model was used to accurately describe the variation of η 0 with UV light exposure time. This study promises to explain the irreversible photosensitive thickening and thinning of tertiary amine viscoelastic micellar systems, while also providing valuable rheological references.