Journal of Membrane Science

journal homepage: www.elsevier.com/locate/memsci

Swelling of 9 polymers commonly employed for solvent-resistant

nanofiltration membranes: A comprehensive dataset

Emiel J. Kapperta,⁎,1, Michiel J.T. Raaijmakersa,2, Kristianne Tempelmana, F. Petrus Cuperusb,

Wojciech Ogiegloa,3, Nieck E. Benesa

a Films in Fluids, Department of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, the Netherlands

b SolSep B.V. Robust Membrane Technologies, St. Eustatius 65, NL-7333 NW Apeldoorn, the Netherlands

A R T I C L E I N F O

Keywords:

Organic solvent nanofiltration (OSN)

Solvent resistant nanofiltration (SRNF)

Polymer swelling dynamics

In situ spectroscopic ellipsometry

A B S T R A C T

The presence of a solvent in a dense polymeric nanofiltration membrane layer can affect the macromolecular

dynamics of the polymer material and the mobility of the solvent penetrant molecules. In addition, even the

affinity of the swollen material for the solvent molecules can be distinct from that of the pure polymer material.

These effects can substantially affect the membrane's performance. This paper provides sorption and swelling

data of 9 thin polymer films that are commonly used for organic solvent nanofiltration (P84, Matrimid, PEI, PAN,

PES, PSf, PEBAX, PTMSP, PDMS) swollen by 10 common solvents (hexane, toluene, dichloromethane, ethyl

acetate, methyl ethyl ketone, acetone, isopropanol, ethanol, methanol, water). The paper describes the swelling

dynamics during short-term solvent exposure (0–8 h), assesses the stability upon long-term solvent exposure (up

to 2 months), and provides quantitative data on the solvent volume fractions inside the swollen layers. Among

the surprising findings are the glubbery behavior of PTMSP and the completely different response of PES and PSf

to toluene exposure. The results of this work demonstrate three crucial findings relevant to organic solvent

nanofiltration membranes and other applications:

1. For many polymers, the swelling changes over long timescales of up to 2 months and longer. Results obtained

on short timescales do however not always allow for direct extrapolation to longer time scales.

2. Structural similarity of polymers does not guarantee similar swelling behavior.

3. Swelling behavior of solvents cannot be solely explained by classifying solvents into aprotic, polar aprotic

and polar protic solvents.

The results of this work can aid in constructing transport models and can help predicting polymer-solvent

compatibility and membrane performance in OSN applications.

1. Introduction

Organic solvent nanofiltration (OSN) membranes separate solvents

from solutes based on the difference in their permeability through the

membrane [1,2]. Solvent permeation through dense nanofiltration

membranes can be described by the combined contributions of the

dissolution of the solvent into the polymer and its diffusion through the

polymer layer. The presence of the solvent in the polymer matrix can

result in changes in the properties of the polymer layer, of which the

most evident change is the swelling of the polymer matrix. In membrane

applications, the swelling of the polymer matrix can result in a

decreased retention of small solutes [3], an increased diffusion coefficient

for the permeating components [4], plasticization [5–8] and/or

pore collapse and mechanical instabilities [1,9].

To study membrane swelling, it is important to distinguish between

the swelling or dilation of the material on one hand and the solvent (mass)

uptake in the layer on the other hand. In the field of membrane science,

the term swelling is often used synonymously with mass uptake,

https://doi.org/10.1016/j.memsci.2018.09.059

Received 30 May 2018; Received in revised form 29 August 2018; Accepted 25 September 2018

⁎ Corresponding author.

1 Present address: BASF SE, Carl-Bosch-Str. 38, 67056 Ludwigshafen am Rhein, Germany.

2 Present address: AkzoNobel Specialty Chemicals, Zutphenseweg 10, P.O. Box 10, 7400AA Deventer, The Netherlands.

3 Present address: Functional Polymer Membranes Group, Advanced Membranes and Porous Materials Ceivision of Physical Sciences and Engineering, King

Abdullah University of Science and Technology (KAUST), Thuwal, Jeddah 23955-6900, Kingdom of Saudi Arabia.

E-mail address: [email protected] (E.J. Kappert).

Journal of Membrane Science 569 (2019) 177–199

Available online 27 September 2018

0376-7388/ © 2018 Elsevier B.V. All rights reserved.

T

Typically, fluids with similar Hanson Solubility Parameters to the polymer will swell and/or dissolve the polymer. The closer the solubility parameters are to the polymer, the more the fluid will provide enhanced solubility of the polymer.

Dear all, you can simply add a plasticizer to break the intrinsic cohesion of the polymer. However, this approach has a major shortcoming, i.e there is risk of migration or leaching of all additives contained in the polymer including the plasticizer itself. The best strategy is via grafting of short segments side groups to the main polymer chain backbone with good affinity to the swelling solvent. In this approach internal cohesion is reduced by the grafts as they act as chain spacers, with no tendency to migration upon swelling. My Regards

Thank you all...