Flexible-templated imprinting for fluorine-free, omniphobic plastics with re-entrant structures

Authors

Xiaoxiao Zhao, Center for BioModular Multiscale Systems for Precision Medicine, Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803, United States.
Daniel S. Park, Center for BioModular Multiscale Systems for Precision Medicine, Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803, United States.
Junseo Choi, Center for BioModular Multiscale Systems for Precision Medicine, Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803, United States.
Sungook Park, Center for BioModular Multiscale Systems for Precision Medicine, Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803, United States.
Steven A. Soper, Departments of Chemistry and Mechanical Engineering, University of Kansas, Lawrence, KS 66045, United States.
Michael C. Murphy, Center for BioModular Multiscale Systems for Precision Medicine, Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803, United States. Electronic address: murphy@lsu.edu.

Document Type

Article

Publication Date

3-1-2021

Abstract

HYPOTHESIS: Compared to vertical micro-pillars, re-entrant micro-structures exhibited superior omniphobicity for suspending liquids to Cassie-Baxter state. However, the existing re-entrant structures rely on complex multi-step deposition and etching procedures. The conventional, rigid-templated imprinting would instead damage the re-entrant structures. This leads to the question: is it possible to preserve the re-entrant curvatures by a flexible-templated imprinting? EXPERIMENTS: We facilely imprinted the re-entrant structures on a plastic substrate using a flexible nylon-mesh template. The effect of imprinting time (15-35 min), temperature (110-120 °C) and pressure (15-50 Bar) was investigated. To further improve the liquid-repellency and abrasion resistance, the silica nanoparticles (30-650 nm) along with epoxy resin binder (10 mg/mL) were pre-coated. FINDINGS: A one-step imprinting is sufficient to fabricate the re-entrant structures by utilizing flexible nylon-mesh template, without damaging the imprinted structures after the demolding process. The pre-coated silica nanoparticles and epoxy resin (1) improved liquid repellency by introducing hierarchical surface structures (e.g. contact angle hysteresis of olive oil reduced > 10°), and (2) acted as a protective layer against mechanical abrasion (omniphobicity maintained after 25 cycles, ~1.6 kPa sand paper abrasion). Additionally, the fluorine-free post-treatment was sufficient for the omniphobicity on the obtained plastic structures.

Publication Source (Journal or Book title)

Journal of colloid and interface science

First Page

668

Last Page

675

Recommended Citation

Zhao, X., Park, D. S., Choi, J., Park, S., Soper, S. A., & Murphy, M. C. (2021). Flexible-templated imprinting for fluorine-free, omniphobic plastics with re-entrant structures. Journal of colloid and interface science, 585, 668-675. https://doi.org/10.1016/j.jcis.2020.10.046