Controlled Swelling of Monolithic Films as a Facile Approach to the Synthesis of UHMWPE Membranes

Konstantin Pochivalov; Andrey Basko; Tatyana Lebedeva; Mikhail Yurov; Alexey Yushkin; Alexey Volkov; Sergei Bronnikov

doi:10.3390/membranes13040422

Controlled Swelling of Monolithic Films as a Facile Approach to the Synthesis of UHMWPE Membranes

Membranes (Basel). 2023 Apr 9;13(4):422. doi: 10.3390/membranes13040422.

Authors

Konstantin Pochivalov¹, Andrey Basko¹, Tatyana Lebedeva¹, Mikhail Yurov¹, Alexey Yushkin², Alexey Volkov^{2

3}, Sergei Bronnikov⁴

Affiliations

¹ G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, 1 ul. Akademicheskaya, 153045 Ivanovo, Russia.
² A.V. Topchiev Institute of Petrochemical Synthesis of the Russian Academy of Sciences, 29 Leninsky Prospect, 119991 Moscow, Russia.
³ Biological and Environmental Science, and Engineering Division (BESE), Advanced Membranes and Porous Materials Center (AMPM), King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia.
⁴ Institute of Macromolecular Compounds of the Russian Academy of Sciences, 31 Bolshoy pr., 199004 St. Petersburg, Russia.

Abstract

A new method of fabricating porous membranes based on ultra-high molecular weight polyethylene (UHMWPE) by controlled swelling of the dense film was proposed and successfully utilized. The principle of this method is based on the swelling of non-porous UHMWPE film in organic solvent at elevated temperatures, followed by its cooling and further extraction of organic solvent, resulting in the formation of the porous membrane. In this work, we used commercial UHMWPE film (thickness 155 μm) and o-xylene as a solvent. Either homogeneous mixtures of the polymer melt and solvent or thermoreversible gels with crystallites acting as crosslinks of the inter-macromolecular network (swollen semicrystalline polymer) can be obtained at different soaking times. It was shown that the porous structure and filtration performance of the membranes depended on the swelling degree of the polymer, which can be controlled by the time of polymer soaking in organic solvent at elevated temperature (106 °C was found to be the optimal temperature for UHMWPE). In the case of homogeneous mixtures, the resulting membranes possessed both large and small pores. They were characterized by quite high porosity (45-65% vol.), liquid permeance of 46-134 L m^-2 h^-1 bar^-1, a mean flow pore size of 30-75 nm, and a very high crystallinity degree of 86-89% at a decent tensile strength of 3-9 MPa. For these membranes, rejection of blue dextran dye with a molecular weight of 70 kg/mol was 22-76%. In the case of thermoreversible gels, the resulting membranes had only small pores located in the interlamellar spaces. They were characterized by a lower crystallinity degree of 70-74%, a moderate porosity of 12-28%, liquid permeability of up to 12-26 L m^-2 h^-1 bar^-1, a mean flow pore size of up to 12-17 nm, and a higher tensile strength of 11-20 MPa. These membranes demonstrated blue dextran retention of nearly 100%.

Keywords: phase diagram; semicrystalline polymer; swelling; thermally induced phase separation; ultra-high molecular weight polyethylene; ultrafiltration membrane.

Grants and funding

The work was carried out within State Programs of ISC RAS, TIPS RAS, and IMC RAS.