TY - JOUR
T1 - Influence of Molecular Weight on the Performance of Polyelectrolyte Multilayer Nanofiltration Membranes
AU - Regenspurg, Jurjen A.
AU - Martins Costa, Ana F.
AU - Achterhuis, Iske
AU - de Vos, Wiebe M.
N1 - Funding Information:
Funding was received from the research programme Innovatiefonds Chemie (LIFT) Project Number 731.016.404, financed by The Netherlands Organisation for Scientific Research (NWO), NX Filtration (Enschede, The Netherlands), and Oasen (Gouda, The Netherlands). This work was also supported by the European Union Horizon 2020 research and innovation program (ERC StG 714744 SAMBA).
Publisher Copyright:
©
PY - 2022/5/13
Y1 - 2022/5/13
N2 - Polyelectrolyte multilayers (PEMs) are highly promising selective layers for membrane applications, especially because of their versatility. By careful choice of the types of polyelectrolyte and the coating conditions, the PEM material properties can be controlled to achieve desired separations. Less understood, however, is how the molecular weight (Mw) of the chosen polyelectrolytes (PEs) will impact layer build-up and thus separation properties. In this work, we investigate the influence of Mw on the performance of two types of PEM-based membranes. PEM membranes have been fabricated from low (15–20 kDa) and high (150–250 kDa) Mw poly(allylamine hydrochloride) (PAH), poly(sodium-4-styrenesulfonate)(PSS), and poly(acrylic acid) (PAA) to obtain PAH/PSS- and PAH/PAA-based nanofiltration membranes. For the linear growing PSS/PAH system, with low PE mobility, the Mw is found to influence the pore closure of the support membrane during coating but not its subsequent performance. In contrast, for the exponentially growing PAH/PAA system with a high PE mobility, much stronger effects of Mw are observed. For low-Mw PAH/PAA PEM membranes, separation properties are found that would be expected of a negatively charged separation layer, while for high-Mw PAH/PAA PEMs a positive separation layer is found. Moreover, molecular weight cutoff (MWCO) measurements show that the low-Mw PAH/PAA multilayers are much denser than their high-Mw counterparts. Here the higher mobility of the small PE chains is expected to lead to more optimal binding between the oppositely charged PEs, explaining the denser structure. Lastly, we find that PEM pH stability is lowest for low-Mw PAH/PAA multilayers which can again be attributed to their higher mobility. Clearly, the Mw can significantly influence the separation performance of PEM-based membranes, especially for more mobile PEM systems such as PAA/PAH.
AB - Polyelectrolyte multilayers (PEMs) are highly promising selective layers for membrane applications, especially because of their versatility. By careful choice of the types of polyelectrolyte and the coating conditions, the PEM material properties can be controlled to achieve desired separations. Less understood, however, is how the molecular weight (Mw) of the chosen polyelectrolytes (PEs) will impact layer build-up and thus separation properties. In this work, we investigate the influence of Mw on the performance of two types of PEM-based membranes. PEM membranes have been fabricated from low (15–20 kDa) and high (150–250 kDa) Mw poly(allylamine hydrochloride) (PAH), poly(sodium-4-styrenesulfonate)(PSS), and poly(acrylic acid) (PAA) to obtain PAH/PSS- and PAH/PAA-based nanofiltration membranes. For the linear growing PSS/PAH system, with low PE mobility, the Mw is found to influence the pore closure of the support membrane during coating but not its subsequent performance. In contrast, for the exponentially growing PAH/PAA system with a high PE mobility, much stronger effects of Mw are observed. For low-Mw PAH/PAA PEM membranes, separation properties are found that would be expected of a negatively charged separation layer, while for high-Mw PAH/PAA PEMs a positive separation layer is found. Moreover, molecular weight cutoff (MWCO) measurements show that the low-Mw PAH/PAA multilayers are much denser than their high-Mw counterparts. Here the higher mobility of the small PE chains is expected to lead to more optimal binding between the oppositely charged PEs, explaining the denser structure. Lastly, we find that PEM pH stability is lowest for low-Mw PAH/PAA multilayers which can again be attributed to their higher mobility. Clearly, the Mw can significantly influence the separation performance of PEM-based membranes, especially for more mobile PEM systems such as PAA/PAH.
KW - Polyelectrolyte multilayer
KW - Nanofiltration
KW - Micropollutants
KW - Tuning parameter
KW - Mobility
KW - Membrane technology
KW - UT-Hybrid-D
U2 - 10.1021/acsapm.1c00826
DO - 10.1021/acsapm.1c00826
M3 - Article
SN - 2637-6105
VL - 4
SP - 2962
EP - 2971
JO - ACS Applied Polymer Materials
JF - ACS Applied Polymer Materials
IS - 5
ER -