Fine tuning the colorimetric response to thermal and chemical stimuli of polydiacetylene vesicles by using various alcohols as additives

In this study, we demonstrate a simple approach for fine tuning the color-transition behaviors of polydiacetylene (PDA) vesicles when exposed to thermal or chemical stimuli. The strength of inter- and intrachain interactions within PDA vesicles, fabricated by using 10,12-tricosadiynoic acid (TCDA) and 10,12-pentacosadiynoic acid (PCDA), are manipulated by mixing with 1-butanol, 1-pentanol or 2-methyl-1-butanol. The swelling of alcohol molecules weakens the interactions within the PDA layers, which in turn affects the color-transition behaviors. We observe that the resultant PDA vesicles exhibit color-transition temperatures ranging from about 35. °C to 55. °C, depending on concentration and structure of the added alcohols. The color-transition temperature and alcohol concentration exhibits linear correlation, where its slope varies with the alcohol structure. This approach is further utilized for controlling the color-transition behaviors of these PDA vesicles upon exposure to chemical stimuli including tetrahydrofuran, pyridine, ethylamine and phenol. The color transition of PDA vesicles at desired concentration of each chemical stimulus can be achieved by varying the concentration of alcohol additives. The ability to control the color-transition behaviors of PDA vesicles is very important for their development as chromatic sensor, extending their utilization in various applications.