SAN-Based Block Polymers as a Platform for Manufacturing Strong Isoporous Membranes

Journal Article · Thu Oct 02 00:00:00 UTC 2025 · Macromolecules

DOI: https://doi.org/10.1021/acs.macromol.5c01452 · OSTI ID:3022053

Mann, Adam N. ^[1]; Wamble, Noah P.  ^[1]; Kuehster, Louise  ^[1]; Landsman, Matthew R. ; Arrowood, Anthony J. ^[1]; Su, Gregory M.  ^[2]; Lynd, Nathaniel A.  ^[1]; Freeman, Benny D.  ^[1]; Sanoja, Gabriel E.  ^[1]

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1. Univ. of Texas, Austin, TX (United States)
2. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)

Ultrafiltration (UF) membranes are ubiquitous in water purification and bioprocessing. However, co-designing their mechanical and transport properties remains challenging because of the broad pore size distributions at the surface and within the bulk that result from nonsolvent-induced phase separation (NIPS) – their typical manufacturing process. These distributions influence the hydrodynamic resistance to water flow and the stress concentrations around the pores. Developing advanced UF membranes requires innovative molecular designs that offer control over the surface and bulk pores, as well as the mechanical properties of the load-bearing, polymer. Here, we introduce a platform for designing UF membranes by leveraging solution self-assembly of block polymers and chain architectures with pendant polar groups. The block polymers consist of a poly(styrene-co-acrylonitrile) hydrophobic block, which is known for its strength, and a poly(4-vinyl pyridine) hydrophilic block, which drives solution self-assembly. We focus on a series of block polymers with constant molecular weight, M_n ≈ 115 kDa, SAN fraction, 75 wt.%, and varying acrylonitrile content, 0 to 40 mol%, to demonstrate that: (i) RAFT dispersion copolymerization of acrylonitrile and styrene provides a facile route to synthesize strong block polymers, (ii) incorporation of acrylonitrile into the hydrophobic block enhances membrane strength by facilitating chain entanglements and dipole-dipole interactions, and (iii) acrylonitrile alters the balance between membrane permeance and rejection, even when the membranes feature similar surface and bulk pores. Overall, our results provide insights into the molecular design of UF membranes with enhanced mechanical and separation properties, contributing to the development of materials for water and energy technologies.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Univ. of Texas, Austin, TX (United States)
• Sponsoring Organization: National Energy Research Scientific Computing Center (NERSC); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: AC02-05CH11231; SC0012704; SC0019272
• OSTI ID: 3022053
• Journal Information: Macromolecules, Journal Name: Macromolecules Journal Issue: 19 Vol. 58; ISSN 1520-5835; ISSN 0024-9297
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English