Light triggered surface motility in a liquid crystal polymer coating

Student thesis: Master

Abstract

Photo-responsive liquid crystal polymer coatings are attracting more attention in various fields of research recently, not only because they can function with a clean and human-friendly stimulus, but also, they enable us to control their function remotely. In addition, altering surface properties remotely is of paramount importance in many soft robotic applications, where controllable adhesion or friction is required, or in biomedical fields where a controllable liquid release is desired. Some requirements for these applications were addressed previously by Gelebart et al., where they developed a photo-responsive liquid secretion coating.
In this research, the primary objective is set to obtain more control over the liquid secretion from the liquid crystal polymer coating, followed by the second objective, which is to test if the coating has the potential of refilling after removing the secreted liquid. As an outcome, a photo-responsive liquid crystal polymer coating is obtained, which is capable of localized secretion of 8CB triggered by UV light (365 nm), using a mask- exposure approach. The secretion is proved to be programmable in advance, by varying the photomask pattern. Under visible light (455 nm) irradiation the liquid can be reabsorbed by the coating, confirming the reversibility of its function. Furthermore, a brand-new approach is implemented to develop fine indentations of hundred nano meters at the coating surface, by washing off the locally secreted liquid. It was proved that not only these surface structures are rather stable at ambient conditions, but also, they can be erased by refilling, providing us with a flat coating again, which has the same functionality as the initial coating.
To summarize the outcomes of this research, a versatile and sustainable functionality is developed in a photo-responsive coating, which can locally release and reabsorb the liquid and moreover, the released liquid can be removed and refilled, where the coating retains its initial properties. This functionality is shown to be fully reversible and reproducible.
Date of AwardApr 2019
Original languageEnglish
SupervisorDanqing Liu (Supervisor 1), Dirk J. Broer (Supervisor 2), Albert P.H.J. Schenning (Supervisor 2), Jaap M.J. den Toonder (External coach) & Yuanyuan Zhan (Supervisor 1)

Keywords

  • Liquid crystals
  • light-responsive
  • Smart material
  • surface motility

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