Effect of cationic surfactants on characteristics and colorimetric behavior of polydiacetylene/silica nanocomposite as time–temperature indicator

•Only pure PDA yielded a hole-like vesicle.•An addition of surfactant led to a decrease in a size of either PDA or PDA/SiO2.•Cationic group of surfactants affected to an appearance of PDA/SiO2.•Surfactant-added PDA/SiO2/F127 solution could change the color below 60°C.•They were expected to be applied as a new polymer-based TTI. Polydiacetylene (PDA)/silica nanocomposites were synthesized by self-assembly method using polymerizable amphiphilic diacetylene monomers, 10,12-pentacosadiynoic acid (PCDA). Addition of cationic surfactants (PDADMAC and CTAB) to PDA/SiO2 nanocomposites induced higher intermolecular force which affected their size, shape and color transition. Pure PDA, PDA/SiO2, PDA/SiO2/PDADMAC and PDA/SiO2/CTAB were investigated by particle size analysis, TEM, SEM, UV–vis spectroscopy and FT-IR. It was found that the PDA/SiO2 nanocomposites exhibited slightly larger particle sizes than those of other samples. The PDA/SiO2 nanocomposites with a core–shell structure were almost regarded as spherical-shaped particles. Cationic surfactants, especially CTAB, presumably affected the particle size and shape of PDA/SiO2 nanocomposites due to the disruption of hydrogen bonding between PDA head group and ammonium group. The colorimetric response of both PDA/SiO2/surfactant and surfactant-free PDA/SiO2 aqueous solutions directly changed in relation to time and temperature; thus they were expected to be applied as a new polymer-based time–temperature indicator (TTI).