Preparation of pH-Responsive PET TeMs by Controlled Graft Block Copolymerisation of Styrene and Methacrylic Acid for the Separation of Water–Oil Emulsions

Muslimova, Indira B.; Omertassov, Dias D.; Zhumanazar, Nurdaulet; Assan, Nazerke; Zhatkanbayeva, Zhanna K.; Korolkov, Ilya V.

doi:10.3390/polym17162221

Open AccessArticle

Preparation of pH-Responsive PET TeMs by Controlled Graft Block Copolymerisation of Styrene and Methacrylic Acid for the Separation of Water–Oil Emulsions

by

Indira B. Muslimova

^1,2,*,

Dias D. Omertassov

^1,2,

Nurdaulet Zhumanazar

¹,

Nazerke Assan

²,

Zhanna K. Zhatkanbayeva

² and

Ilya V. Korolkov

^1,2,*

¹

The Institute of Nuclear Physics, Ibragimov Str. 1, Almaty 050032, Kazakhstan

²

L.N. Gumilyov Eurasian National University, Satpaev Str., 2, Astana 010000, Kazakhstan

^*

Authors to whom correspondence should be addressed.

Polymers 2025, 17(16), 2221; https://doi.org/10.3390/polym17162221

Submission received: 20 June 2025 / Revised: 6 August 2025 / Accepted: 12 August 2025 / Published: 14 August 2025

(This article belongs to the Special Issue Modification and Functionalization of Polymer Materials for Sustainable Development)

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Abstract

To develop membranes capable of efficient and switchable emulsion separation under variable pH conditions, pH-responsive surfaces were engineered on poly(ethylene terephthalate) track-etched membranes (PET TeMs) via a two-step UV-initiated RAFT graft polymerization process. Initially, polystyrene (PS) was grafted to render the surface hydrophobic, followed by the grafting of poly(methacrylic acid) (PMAA) to introduce pH-responsive carboxyl groups. Optimized conditions (117 mM MAA, RAFT:initiator 1:10, 60 min UV exposure at 10 cm) resulted in PET TeMs-g-PS-g-PMAA surfaces exhibiting tunable wettability, with contact angles shifting from 90° at pH 2 to 65° at pH 9. Successful grafting was confirmed by FTIR, AFM, SEM, TGA, and TB dye sorption. The membranes showed high degree of rejection (up to 98%) for both direct and reverse emulsions. In direct emulsions, stable flux values (70 ± 2.8 to 60 ± 2.9 L m⁻² h⁻¹ for cetane-in-water and 195 ± 8.2 to 120 ± 6.9 L m⁻² h⁻¹ for o-xylene-in-water) were maintained over five cycles at 900 mbar, indicating excellent antifouling performance. Reverse emulsions initially exhibited higher flux, but stronger fouling; however, flux recovery reached 91% after cleaning. These findings demonstrate the potential of PET TeMs-g-PS-g-PMAA as switchable, pH-responsive membranes for robust emulsion separation.

Keywords: pH-responsive membranes; track-etched membranes; RAFT graft polymerization; separation; antifouling; poly(ethylene terephthalate)

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MDPI and ACS Style

Muslimova, I.B.; Omertassov, D.D.; Zhumanazar, N.; Assan, N.; Zhatkanbayeva, Z.K.; Korolkov, I.V. Preparation of pH-Responsive PET TeMs by Controlled Graft Block Copolymerisation of Styrene and Methacrylic Acid for the Separation of Water–Oil Emulsions. Polymers 2025, 17, 2221. https://doi.org/10.3390/polym17162221

AMA Style

Muslimova IB, Omertassov DD, Zhumanazar N, Assan N, Zhatkanbayeva ZK, Korolkov IV. Preparation of pH-Responsive PET TeMs by Controlled Graft Block Copolymerisation of Styrene and Methacrylic Acid for the Separation of Water–Oil Emulsions. Polymers. 2025; 17(16):2221. https://doi.org/10.3390/polym17162221

Chicago/Turabian Style

Muslimova, Indira B., Dias D. Omertassov, Nurdaulet Zhumanazar, Nazerke Assan, Zhanna K. Zhatkanbayeva, and Ilya V. Korolkov. 2025. "Preparation of pH-Responsive PET TeMs by Controlled Graft Block Copolymerisation of Styrene and Methacrylic Acid for the Separation of Water–Oil Emulsions" Polymers 17, no. 16: 2221. https://doi.org/10.3390/polym17162221

APA Style

Muslimova, I. B., Omertassov, D. D., Zhumanazar, N., Assan, N., Zhatkanbayeva, Z. K., & Korolkov, I. V. (2025). Preparation of pH-Responsive PET TeMs by Controlled Graft Block Copolymerisation of Styrene and Methacrylic Acid for the Separation of Water–Oil Emulsions. Polymers, 17(16), 2221. https://doi.org/10.3390/polym17162221

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Preparation of pH-Responsive PET TeMs by Controlled Graft Block Copolymerisation of Styrene and Methacrylic Acid for the Separation of Water–Oil Emulsions

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