Functional Sulfonated Polymer
What is Functional Sulfonated Polymer?
Functions of sulfonated group contain proton conductivity, electron conductivity and hydrophilicity, etc. In recent years, sulfonated polymer materials such as ion exchange materials, separator for battery, and separation membrane are attracting attention.
Sulfonated Polyether sulfone【S-PES】
We hereby introduce Functional Sulfonated Polymer which is Sulfonated Polyether sulfone(S-PES)
■Typical structural formula of Sulfonated Polyether sulfone(S-PES)
■An example of S-PES quality
| Items | An example of S-PES quality |
|---|---|
| Appearance | Light brown powder |
| Sulfonation degree | 30% |
| Water contents | ≤ 3% |
| Weight-average molecular weight | 130,000 |
| Developmental stage | Pilot stage |
Novel Sulfonation Technology
Sulfonation of polymers in the conventional technology had the problem that the molecular weight declined as the reaction progressed. We developed a new sulfonation method for aromatic polymers and succeeded in achieving both high sulfonation degree and prevention of molecular weight reduction. (Konishi Chemical Ind. Co., Ltd. Patent No. JP5824734, US9228060, KR10-1731242, CN103998492, DE112012005418, TW522394)
■New manufacturing method of S-PES
| New method | Conventional-1 | Conventional-2 | Raw material PES | Target | |
|---|---|---|---|---|---|
| Sulfonation degree | 30% | 9% | 30% | - | 30% |
| Weight-average molecular weight | 130,000 | 100,000 | 20,000 | 100,000 | 100,000～150,000 |
The following are examples of application of S-PES to water treatment membrane and ion exchange membrane for redox flow battery.
Application to water treatment membrane
S-PES/PES blend hollow fiber membrane module improved fouling resistance compared to PES membrane.
What is fouling?
The hydrophobic surface adsorbs organic compounds etc. due to the interaction.
■S-PES/PES blend hollow fiber membrane
Figure：The morphology of pure PES(M22-0) and S-PES/PES (M20-10：S-PES/PES ratio：1/9) blend hollow fiber membranes
■Air bubble contact angle
The surface hydrophilicity of the PES and S-PES/PES blend membranes were characterized by the air bubble contact angle. We measured contact angle between membrane and air in water.
The results indicated that the S-PES/PES blend membranes was more hydrophilic than the PES membrane.
Figure： Air bubble contact angle of PES and S-PES/PES blend membrane(S-PES/PES ratio：1/9)
■S-PES/PES blend hollow fiber membrane module
The drying bundle of the hollow fiber membranes(M22-0, M20-10) was placed into a module with a length of 1 m and ~ 330 pieces of fibers. The module was designed to be an “out to in” filtration type and hollow fibers only opened at one end.
The photo of full size membrane module with the length of 1 m.
The outlet for the permeate solution of a membrane module.
■Antifouling Properties of Membrane Modules
Typical model foulants (sodium alginate(SA), sodium humate(HA) and bovine serum albumin (BSA)) were used to evaluate the membrane antifouling properties. The flux decay during fouling process for S-PES/PES blend hollow fiber membranes module was obviously suppressed when compared with that for PES hollow fiber membranes module.
SA 100 ppm
HA 100 ppm
BSA 100 ppm
■（MD22-0)：PES
●（MD20-10)：S-PES/PES membrane module
Figure: Effect of different model foulants (SA, HA and BSA) on the antifouling properties of full-size membrane modules.
【引用】
H. Matsuyama et al., Ind. Eng. Chem. Res., 2017, 56, 11302–11311
H. Matsuyama et al., Ind. Eng. Chem. Res., 2018, 57, 4430−4441
Application to ion exchange membrane for redox flow battery
S-PES membrane was investigated as ion exchange membranes for vanadium redox flow battery (VRFB) applications. The S-PES membrane exhibited good stability and high performance.
■ Membrane durability test in vanadium sulfate solution
The S-PES membrane had excellent durability properties as same as perfluoro carbon membrane.
■ Crossover test
The S-PES membrane exhibited much superior proton/vanadium ion selectivity to perfluoro carbon membrane.
| Membrane durability ※1 | Crossover ※2 | |
|---|---|---|
| S-PES membrane | 1.0 | 1.1 x 10-7 cm2/min |
| Perfluoro carbon membrane | 1.0 | 4.8 x 10-7 cm2/min |
| S-PEEK membrane | 3.7 | 1.1 x 10-6 cm2/min |
※1：V4+ concentration increase rate in the vanadium solution Relative comparison in UV-visible absorption spectrum. blank：1.0. ※2：V4+ diffusion coefficient
【References】
National Institute of Advanced Industrial Science and Technology （AIST）evaluation result