Thickness-Dependent Swelling Behavior of Vapor-Deposited Hydrogel Thin Films

• Main Authors: Fabian Muralter, Alberto Perrotta, Anna Maria Coclite
• Format: Article
• Language: English
• Published: MDPI AG 2018-12-01
• Series: Proceedings
• Subjects: hydrogel; thin film; thickness; LCST; lower critical solution temperature; iCVD; initiated Chemical Vapor Deposition; temperature-responsive
• Online Access: https://www.mdpi.com/2504-3900/2/13/757

Hydrogel thin films containing temperature sensitive chemical functionalities (such as <i>N</i>-isopropylacrylamide, NIPAAm) are particularly interesting for sensor and actuator setups. Complex 3D structures can be conformally coated by the solvent free technique initiated Chemical Vapor Deposition, with precise control over chemical composition and film thickness. In this study, NIPAAm-based thin films with film thicknesses ranging from tens to several hundreds of nanometers and with different amounts of cross-linking were deposited. Above the lower critical solution temperature (LCST), these films repel out water and hence shrink. The amount of cross-linking and the deposited film thickness were successfully identified to both affect shape and position of the LCST transition of these systems: a promising basis for tuning response properties.