Jaana Vapaavuori: Taming Macromolecules by Light - Supramolecular Photoresponsive Materials at Three Different Length Scales
|Wanneer:||wo 14-02-2018 15:45 - 16:45|
When noncovalently bound to macromolecules, photoresponsive azobenzene derivatives can be harnessed for controlling the properties of materials at length scales spanning at least three orders of magnitude. In this presentation, I will discuss my recent work seeking fundamental understanding of how the nanometer-scale photoinduced changes in azobenzene geometry can be translated into different applications involving polymers. First, starting from the length scale of 10-100 nm, the morphology of self-assembled diblock copolymers can be switched by supramolecularly attaching azobenzene molecules selectively to one of the blocks. Second, by using a novel IR method, the molecular-level origins of the photoinduced surface patterning, in which azobenzene motion is converted into micron-scale material motion, are elucidated. Third, stimuli-induced (light and humidity) changes visible at the macroscopic scales are discussed, by introducing supramolecular polymer-azobenzene humidity memories and light-switchable polymer wrinkles at the scale of approximately 10-100 μm. This presentation highlights that the key to achieving high-tech applications is to first understand the delicate balance of supramolecular interactions in soft condensed materials, and then develop methods for controlling them.