Effects of Nanoparticle Concentration and Plasticizer Type on Colorimetric Behavior of Polydiacetylene/Silica Nanocomposite as Time-temperature Indicator

Effects of silica nanoparticle concentration and plasticizer type on color transition of PDA/SiO2 nanocomposite were investigated. Four types of plasticizer were poly(ethylene glycol-400), glycerol, xylitol and sorbitol. The number of hydroxyl groups in polyol affected to the stability of PDA/SiO2 nanocomposite molecules. The color of plasticized PDA films exhibited a stronger purple color tone than those of plasticized PDA/SiO2 films. As increasing time and temperature, the color change of plasticized PDA films occurred faster than plasticized PDA/SiO2 (10 wt.%) films and plasticized PDA/SiO2 (20 wt.%) films, respectively. Higher concentration of silica nanoparticles yielded higher stability of PDA/SiO2 nanocomposite molecules. Plasticized PDA and plasticized PDA/SiO2 films clearly changed the color from blue to purple, reddish purple and finally red stored at higher temperature (35 °C), whereas they only shifted the color from blue to purple kept at lower temperature (5 °C) throughout storage time. This study confirmed that it is possible to develop a time-temperature indicator for applying with chilled food products.