مشخصات پژوهش

BACKGROUND: perylene bisimide pigments are one of the high performance pigment categories which are utilized in near infrared reflective coatings. The structure-near infrared activity relationship in the perylene pigments is unknown up to now. RESULTS: Some of the factors suggested by previous researches affecting the near-infrared (NIR) reflectance of perylene-bisimide derivatives were investigated in this study and some are validated while some others are rejected. In the visible region, there are substantial differences between absorption spectra of the pigments in the solid-state and dissolved form indicating that crystallochromic phenomenon presents in the pigments. NIR properties of the synthesized pigments are investigated and the results exhibit an obvious correlation between the imide substitution structure and NIR properties of the pigments. However, a direct relationship cannot be established. Aliphatic substituted PDIs usually exhibit lower reflectance values in comparison to aromatic substituted ones but there are some exceptions in this regard. The results of UV-Vis-NIR reflectance spectra of each pigment were reported in both white and black substrates and in this regard, the synthesized pigments were classified. All the PDIs fall into absorbent-transparent category in the NIR region. Thermogravimetric analysis indicates that all the PDIs have a heat resistance of at least 200 ºC. CONCLUSION: structure-NIR reflectance relationship of the five synthesized perylene pigments is evaluated in which the results illustrate that the N-substitution of the imide group can significantly influence on the cool activity of the pigments.