"This is the peer reviewed version of the following article: [Daniel, D., Goh, S. S., Truong, T. N. B., Koh, X. Q., &amp;amp;amp; Tomczak, N. (2020). Origin of Underwater Oil‐Repellence in Polyelectrolyte Brush Surfaces. Advanced Materials Interfaces, 8(2), 2001203. ], which has been published in final form at [doi:10.1002/admi.202001203]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."