Atomic Layer Deposition for Gradient Surface Modification and Controlled Hydrophilization of Ultrafiltration Polymer Membranes

Abstract

In recent years, atomic layer deposition (ALD) has emerged as a powerful technique for polymeric membrane surface modification. In this research, we study Al 2 O 3 growth via ALD on two polymeric phase-inverted membranes: polyacrylonitrile (PAN) and polyetherimide (PEI). We demonstrate that Al 2 O 3 can easily be grown on both membranes with as little as 10 ALD cycles. We investigate the formation of Al 2 O 3 layer gradient through the depth of the membranes using high-resolution transmission electron microscopy and elemental analysis, showing that at short exposure times, Al 2 O 3 accumulates at the top of the membrane, reducing pore size and creating a strong growth gradient, while at long exposure time, more homogeneous growth occurs. This detailed characterization creates the knowledge necessary for controlling the deposition gradient and achieving an efficient growth with minimum pore clogging. By tuning the Al 2 O 3 exposure time and cycles, we demonstrate control over the Al 2 O 3 depth gradient and membranes' pore size, hydrophilicity, and permeability. The oil antifouling performance of membranes is investigated using in situ confocal imaging during flow. This characterization technique reveals that Al 2 O 3 surface modification reduces oil droplet surface coverage.

Improving Li Anode Reversibility in Li–S Batteries by ZnO Coated Separators Using Atomic Layer Deposition

“…Interestingly, the amount of Zn is increased with number of cycles in a nonlinear way, the measured ICP AES values (in ppm under the current experimental conditions) for 25, 35, and 50 ALD cycles are 0.0068, 0.0826, and 0.2316 respectively. We attribute this observation to the unique morphology of the coated substrate similar to cylindrical substrate on which a linear growth will end up with nonlinear volumetric change (dependence on radius in power of 2)of the ZnO on-to and into the porous polymer, 26,27 a more comprehensive analysis of the growth mechanism is beyond the scope of the current paper, since the major goal here was to modify the surface with ZnO with controllable effect on porous structure (to be shown below).…”

Atomic layer deposition enables multi-modal three-dimensional electron microscopy of isoporous membranes

“…In SNIPS membranes as well as in other filtration membranes, electron microscopy is a central tool for characterizing and studying the membrane structure and correlating between the nanoscale structure and the membrane's performance. 17,[23][24][25] Typically, scanning electron microscopy (SEM) is used to probe the surface properties, such as the pore size and its distribution, and the membrane's cross-sectional morphology. 26 Transmission electron microscopy (TEM) is often used to observe the membrane at high magnifications, allowing insights into the pore morphology.…”

Mechanical Behavior of Hybrid Thin Films Fabricated by Sequential Infiltration Synthesis in Water-Rich Environment

“…2,3 These novel materials benefit from the synergic interactions, presenting improved properties compared to bulk scale composites, such as enhanced UV and chemical stability 4 and augmented optical, 1,5 mechanical, 6,7 thermal, 1 and electrical 8 performance. Thus, it is not surprising that hybrid materials are marked as potential key features for various advanced applications such as flexible and stretchable electronics and sensors, 9,10 optical devices, 11,12 membranes, 13,14 and energy storage devices. 15,16 One of the intriguing features of hybrid materials is their unusual mechanical properties.…”

“…However, unlike traditional bulk-scale composites, which consist of a matrix and filler dispersion at the micron and submicorn levels with distinct interfaces between the phases, hybrid materials comprise constituents at the nanoscale and molecular levels, with physical or chemical interactions between them. , These novel materials benefit from the synergic interactions, presenting improved properties compared to bulk scale composites, such as enhanced UV and chemical stability and augmented optical, , mechanical, , thermal, and electrical performance. Thus, it is not surprising that hybrid materials are marked as potential key features for various advanced applications such as flexible and stretchable electronics and sensors, , optical devices, , membranes, , and energy storage devices. , …”

“…It has been demonstrated, for example, in poly­(methyl methacrylate) (PMMA), − poly­(2-vinylpyridine) (P2VP), SU-8, and polyvinyl alcohol (PVA) through growing inorganic materials such as aluminum oxide (AlO x ), − zinc oxide (ZnO x ), titanium oxide (TiO x ), indium oxide (InO x ), and gallium oxide (GaO x ) . The high precision of SIS and the plethora of matrix materials are the foundation for developing advanced applications such as advanced membranes, , antireflective coatings, and hydrophobic surfaces …”