| Fabricating technologies for functional surfaces are worth studying due to itsimportance for development of interface science. In this thesis, LB films of switchablespiropyran molecule SP-12, which has different light-triggered changes of itsmolecular structure and surface morphology under various pressure, were successfullyfabricated by Langmuir-Blodgett technology. It is found that the LB films have twodifferent molecular scale self-healing behaviors. Deduced from the available dataobtained, a rational mechanism is conjectured to explain both phenomena.The optical microscope and atomic force microscopy (AFM) were employed tocharacterize the surface structure and self-healing performance. Differentlight-triggered morphological changes, including two molecular level self-healingprocess, are found on the LB films fabricated at different surface pressure. These lighttriggered morphological changes of SP-12films under UV or visible light radiationare resulted from structural transformation of the molecule.To find more proofs for the conjectured mechanism, light-triggered contact anglechanges of SP-12LB films and their change speed were further studied in details. Theresults confirm the light-triggered film morphological changes proceed in both microand nano scales. Combining the results of the contact angle test, Brewster angle microscopyimages and Gaussian simulation, a rational mechanism of the molecular levelself-healing is deduced, that is resulted from structural twist and molecular movementof the SP-12, and it is further amplified by their ordered arrangement.The self-healing effect in molecular level showed in this thesis can be used toreduce surface defects. In addition, the mechanism proposed here based on theprinciple of the ordered arrangement successfully connect the different scale ofmorphological behavior from nanoscopic to mesoscopic and the macroscopic range. |
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