UV-Assisted Graft Polymerization of N-vinyl-2-pyrrolidinone onto Poly(ether sulfone) Ultrafiltration Membranes:  Comparison of Dip versus Immersion Modification Techniques

Abstract

Two different techniques were used to photochemically modify 50 kDa poly(ether sulfone) (PES) membranes with the monomer N-vinyl-2-pyrrolidinone (NVP) to increase surface wettability and decrease adsorptive fouling during the constant volume diafiltration of 0.1 wt % bovine serum albumin (BSA). The filtration performance of the modified membranes was compared to that of a commercially available PES membrane and a regenerated cellulose membrane. Both the dip and immersion modification techniques produced membranes with essentially the same wettability as regenerated cellulose, a wettability increase of 30% over the base PES membrane. There was a substantial decrease in the irreversible adsorptive fouling of the base membrane as measured by the permanent flux drop after water cleaning with respect to the initial buffer flux using either modification (from 0.42 to 0-0.09). The immersion-modified membrane with the best performance exhibited no adsorptive fouling, similar permeability, and higher rejection than the regenerated cellulose membrane. Both modification techniques sharply decreased membrane permeability at high monomer concentrations due to pore blockage by grafted polymer chains. The dip-modified membranes exhibited simultaneous loss of BSA rejection and permeability, which suggested that although radiation cleaved PES bonds and enlarged the pores, the high degree of grafted polymer chains on the surface blocked the pores and decreased the permeability. The immersionmodified membranes retained their rejection because the monomer NVP solution was found to absorb up to 88% of the emitted energy, depending on its concentration, thereby protecting the pore structure from intense irradiation. Thus, the dip and immersion techniques are useful for applications where high protein transmission and retention are desired, respectively.

An Optically Reversible Switching Membrane Surface

“…1 Preparation of modified membranes: 30-kDa PES membranes were modified by using a UV-induced graft polymerization method as described in detail in Taniguchi, Belfort and co-workers. [3,6,15,16] A Rayonet photochemical chamber reactor system (Model RPR-100, Southern New England, Ultraviolet Co., Branford, CT) containing 300-nm UV lamps ( % 15 % of the energy was at < 280 nm) was used. The membranes were dipped in spyropyran monomer solution (1 % w/v in ethyl acetate) for 1 h with stirring at 22 AE 1 8C, removed from the monomer solution, purged with N 2 for 10 min, and irradiated with 300-nm UV light in water-saturated N 2 for 4 min.…”

“…Previously, binding of photochromic moieties to solid substrates required complicated and multi-step procedures, [13,14] whereas herein we use a relatively simple two-step dip and UV-irradiation process that could be easily incorporated into a commercial manufacturing process. [15] The challenge was to synthesize optically active vinyl spiropyran (1'-(2-propylcarbamylmetha- pyran-2,2'-indoline) and determine whether the photografting process that uses UV light at 300 nm would allow the vinyl spiropyran molecules to graft and retain their switchable properties. A commercial PES 30-kDa synthetic membrane filter was chosen as a model membrane surface because of its high sensitivity to 300-nm UV radiation and because it is one of the most widely used polymeric materials that is used to produce commercial ultrafiltration membranes and support layers for reverse osmosis and nanofiltration membranes.…”

Surface modification of chromatography adsorbents by low temperature low pressure plasma

“…These polymer coated materials were characterised by selectivity indices less than unity (Fig 4b). Poly(vinyl pyrrolidone) is widely recognized as a potentially important surface modification agent for biomedical and bioprocessing applications, given its excellent biocompatibility with living tissues and extremely low cytotoxicity [70], and that it prevents cell adhesion, inhibits binding of platelets [52] and plasma proteins [51,52,63], increases surface wettability and reduces adsorptive fouling [48][49][50]. Numerous studies conducted with model proteins, including BSA, confirm that 5 modification of a given support material with poly(vinyl pyrrolidone) significantly reduces protein adsorption.…”

“…The 20 ability to change the characteristics of a given material surface from hydrophobic to hydrophilic or vice versa is another important application of plasma technology. The modification of chromatography supports using plasma methods is, in contrast to membrane materials [43,[47][48][49][50][51][52], not well documented, and most reports to date have concerned fabrication of restricted access packing materials for analytical separations of small molecules 25…”

Surface Functionalization by Grafting (2-Dimethylamino)ethyl Methacrylate Methyl Chloride Quaternary Salt (DMAEMAq) onto Hollow Fiber Polyethersulfone (PES) Membranes for Improvement of Antibiofouling Properties

“…Hydrophilic modifiers such as N-vinyl-2-pyrrolidone (NVP), acrylic acid (AA) and acylamide (AAm) monomers or monomers containing hydroxyl or amine groups have been used for surface modification of PES membranes [13][14][15][16]. Zhu et al [17] modified a porous PES membrane by corona-induced graft polymerization of acrylic acid (AA).…”