(357e) Design of Functionalized Membranes for Advanced Filtration Processes

Membrane technology is one of the most cost-effective and environmentally friendly separation techniques. However, the performance of membranes is often limited by (i) a tradeoff between the two key performance indicators, i.e., permeability and selectivity, and (ii) reduced membrane performance due to membrane fouling, which refers to the accumulation of matters and living microorganisms on a submerged surface.

To address those challenges in membrane science, I design and synthesize functional polymer thin films using the technique termed initiated Chemical Vapor Deposition (iCVD), and apply them to nanoporous membranes to achieve (i) narrowed pore size distribution, which simultaneously improves membrane selectivity and permeability, thus overcoming the aforementioned tradeoff; and (ii) antifouling/antimicrobial surfaces on the internal walls of nanopores in a membrane to maintain the performance and lifetime of membranes. While past research in iCVD has applied antifouling coatings to non-porous membranes, their application to nanoporous substrates has not been demonstrated. Furthermore, there is a critical knowledge gap in the effect of nanoconfinement on polymerization kinetics when it comes to iCVD polymerization, limiting the development of thickness-controlled polymer coatings for nanoporous membranes.

To address those challenges, my research in the past four years has enabled a detailed understanding of the deposition kinetics of 4-aminostyrene (AS) inside nanopores of 80 to 200 nm, and AS was chosen because its amine group enables further functionalization to boost membrane selectivity. As discussed in my publications #1,2,3 and pending submission #4 below, my research revealed a two-stage growth mechanism of iCVD polymers, which in turn enabled a narrowed pore size distribution in membranes with pores larger than 100 nm. To prevent membrane fouling, a series of environmentally friendly dual-functional and amphiphilic copolymers was developed, which outperformed a zwitterionic coating, i.e., the gold standard in antifouling chemistries, by over 39.3% as demonstrated by Pseudomonas aeruginosa biofilm formation (publication #5, and pending submission #6). My recent endeavors enabled the design of antifouling materials guided by advanced machine learning algorithms (pending submission #7). The future directions would focus on studying bacteria-surface interactions to understand the mechanism behind amphiphilic surfaces.

Research Interests: functional polymer thin films, coatings, anti-biofouling and antimicrobial coatings, Chemical Vapor Deposition, biomaterials, bacteria-surface interactions, polymers, enzyme immobilization and kinetics, biointerface, biofilm, membranes, nanoscale engineering, membrane-based separations, surface engineering, polymer thin film synthesis and characterization.

Publications:

1. Khlyustova, A., Yang, R*. Initiated Chemical Vapor Deposition Kinetics of Poly(4-aminostyrene). Frontiers in Bioengineering and Biotechnology, 2021, 9, 670541.

2. Cheng, Y.†, Khlyustova, A.†, Yang, R*. Kinetics of All-Dry Free Radical Polymerization under Nanoconfinement. Macromolecules, 2020, 53, 24, 10699-10710.

3. Cheng, Y.†, Khlyustova, A.†, Yang, R*. All-dry Free Radical Polymerization inside Nanopores: Ion-Milling-Enabled Coating Thickness Profiling Revealed 'Necking' Phenomena. Journal of Vacuum Science & Technology A, 2022, 40 (3), 033406.

4. Khlyustova, A.†, Cheng, Y.†, Yang, R*. Narrowing Pore Size Distribution by Initiated Chemical Vapor Deposition. ACS Macro Letters (in preparation).

5. Khlyustova, A., Kirsch, M., Cheng, Y., Yang, R*. Surfaces with Antifouling-Antimicrobial Dual Function via Immobilization of Lysozyme on Zwitterionic Polymer Thin Films. Journal of Materials Chemistry B, 2022, 10 (14), 2728-2739.

6. Khlyustova, A., Kirsch, M., Yang, R*. AmphiphilicCopolymer Thin Films with Short Fluoroalkyl Side Chains for Antifouling Properties at Solid-Liquid-Air Interface. ACS Sustainable Chem. Eng., submitted.

7. Feng, Z.†, Cheng, Y.†, Khlyustova, A. †, Wani, A.A., Franklin, T., Hook., A.*, Varner, J.D.*, Yang, R*. Virtual High-throughput Screening of Vapor-Deposited Amphiphilic Polymers for Biofilm Reduction with Machine/Deep Learning. Advanced Materials, submitted.