Hydrophilic Surface Modification of Microporous Polymer Membranes Using A Variety of Low-Temperature Plasma Treatments

Abstract

A variety of plasma treatments have been employed to achieve permanent hydrophilic surfaces throughout the membrane structure. Specifically, we have modified microporous polyethersulfone (PES) membranes using H 2 O, CO 2 , and N 2 plasma treatments to implant polar functional groups; alternatively, Ar-plasma treatment followed by grafting of hydrophilic monomers (acrylic acid and acrylamide) in the vapor phase has also been successful at modifying PES membranes. PES membranes treated with H 2 O and CO 2 plasmas as well as the grafted membranes are found to be permanently hydrophilic (for a minimum of six months), and the entire membrane cross-section is modified. Chemical changes to the modified PES membranes were determined with FTIR and XPS measurements. Furthermore, water bubble point measurements and electron microscopy results reveal that pore sizes of the modified membranes are only slightly affected, depending on the treatment. Incorporation of polar functionalities results in an increase in the glass transition temperature (T g ) and a moderate change in tensile strength of the modified membranes. Most importantly, the surfaces of the modified membrane are less susceptible to absorption by bovine serum albumin (BSA) proteins.

Hydrophilic Modification of Polysulfone Ultrafiltration Membranes by Low Temperature Water Vapor Plasma Treatment to Enhance Performance

“…Low‐temperature plasmas can be used to modify the surface properties of polymeric membranes via film deposition, functional group implantation, or plasma graft copolymerization . Some limitations of plasma‐based techniques include possible damage to the membrane by interactions with plasma species, non‐uniform plasma treatment across the thickness of the membrane, as well as the potential for short‐lived modification depending on the treatment parameters and material properties.…”

“…Thus, it is not clear whether the modification was the result of chemical or morphological changes. We previously reported inductively coupled rf water vapor [H 2 O (v)] plasma treatment of sub‐micron PSf membranes . In these studies, the membrane was placed perpendicular to the gas flow, ∼9 cm downstream from the most intense region of the plasma glow to achieve gas flow through the membrane and minimize membrane damage.…”

Chemical and morphological modification of polyethersulfone membrane and film following krypton florid laser irradiation

“…1 Though PES and PES-based membranes have been widely used, the hydrophobic character of PES is a disadvantageous in many applications. 2,3 Therefore, many efforts have been made to improve the hydrophilicity and anti-fouling ability of PES membrane to optimize its performance. [4][5][6][7] Modification procedures lead to a compromise between hydrophobicity and hydrophilicity of the membrane.…”

“…Polyethersulfone (PES) is an attractive material that has been used in various applications such as biology due to its excellent chemical resistance, good mechanical strength, and thermal endurance 1 . Though PES and PES-based membranes have been widely used, the hydrophobic character of PES is a disadvantageous in many applications 2 , 3 . Therefore, many efforts have been made to improve the hydrophilicity and anti-fouling ability of PES membrane to optimize its performance 4 …”