- Zhao, Yuejun and Chen, Tao and Zhang, Xiaodong and Zauscher, Stefan and Chen, Chuan-Hua, Development of an Adaptive Vapor Chamber with Thermoresponsive Polymer Coating,
in PROCEEDINGS OF THE ASME MICRO/NANOSCALE HEAT AND MASS TRANSFER INTERNATIONAL CONFERENCE, VOL 3
pp. 395-398 .
(last updated on 2011/08/19)
We propose a novel concept for an adaptive vapor chamber using a thermoresponsivc polymer coating to enhance heat transfer and reduce local thermal gradients. By coating the wick structures with stimulus-responsive polymer brushes with an upper critical solution temperature (UCST), the hotter surface becomes more wettable than the colder surface. The smaller contact angle at higher temperature generates larger capillary forces and promotes stronger return flow toward the hotspots. In this paper, we present our progress toward developing the adaptive vapor chamber. We have grafted poly(2-(meth-acryloyloxy)ethyl(dimethyl(3-sulfopropyl) ammonium hydroxide) (PMEDSAH) brushes on silica wafers, and the PMEDSAH polymer coating exhibits UCST properties with stable and tunable wettability. We have captured infrared images of the evaporator with steady and transient heating, and developed a thermographic technique that can be used to test the adaptive wick functionality in a vapor chamber.