Thermal imaging applications using polydiacetylene supramolecules

Abstract

In this thesis, thermal imaging applications using polydiacetylene (PDA) supramolecules were presented. Four novel applications were studied in detail by using the thermochromic and thermofluorescence features of the PDA vesicles. In the first phase, a temperature sensitive self-standing microchip platform was fabricated by using replica molding (REM) method. Functional three-dimensional (3D) micropatterns of diacetylene supramolecules embedded in a host polymer, polyvinyl alcohol (PVA), were successfully transferred from a SU-8 master. The measurements proved that a significant dimensional reduction of the prepared patterns due to curing process did not disturb the conformational structure of the micro-scale replicated features. Polymerization of the diacetylene vesicles using 254nm UV-light irradiation from the back-side of the transparent substrate induced blue color polydiacetylene (PDA) micro-images selectively in the molded areas owing to the sub- 300nm light blocking property of SU-8. Heat treatment to the chip caused a blue-to-red color transition of the 3D micropatterns and as a consequence, generation of fluorescence signal from the red phase was observed. The second application covered an all-organic counterfeit detection label based on polydiacetylene (PDA) supramolecules. Distinctive chemical and material properties of PDAs comprised the signatures of originality and render a new generation, multi-step anti-fake inspection system. Replica molding method was used to fabricate 3-D patterns on the composite film of PDA and polyvinyl alcohol. The height and frequency of the patterns were particularly designed to match to the human tactile perception so that they were recognized as intaglio printings for tactile confirmation. The intriguing characteristics of as prepared 3-D structures: a) visible blue-to-red thermochromic transition b) photo-sensitivity to generate colored micro-patterns and c) thermally induced non-fluorescent to fluorescent swit...