Janus Membranes via Diffusion‐Controlled Atomic Layer Deposition

• DOI: 10.1002/admi.201800658
• Publication Date: 2018-06-13T05:46:39Z
• Authors: Ruben Z. Waldman; Hao‐Cheng Yang; David J. Mandia; Paul F. Nealey; Jeffrey W. Elam; Seth B. Darling
• Keywords: Deposition

Abstract The first use of atomic layer deposition (ALD) to produce Janus membranes is reported, with an example system consisting a compositional gradient ranging from hydrophilic Al 2 O 3 on one face hydrophobic poly(propylene) the opposite face. Alternating pulses trimethyl aluminum and water vapor lead growth covalently bonded conforming membrane pore surfaces. Precise control ALD parameters significantly affects surface wetting modified depth infiltration into porosity. This derives slow precursor diffusion through 200 nm pores compared much faster reactions. For given exposure purge time, increasing number cycles decreases contact angle at hydrophilic, until droplet completely imbibed by membrane. To demonstrate utility these membranes, hydrophilic/superaerophobic treatment shown greatly reduce size air bubbles generated membrane, enabling mixing. technique represents application vapor‐deposited metal oxides form membranes. Further opportunities are afforded ability laterally pattern across via physical masking.