Department of Chemistry and Applied Biological Sciences and ‡Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology , Rapid City, South Dakota 57701, United States.
ACS Appl Mater Interfaces. 2017 Feb 1;9(4):4272-4278. doi: 10.1021/acsami.6b16116. Epub 2017 Jan 19.
Electrospun nanofiber membranes (ENMs) have demonstrated promising applications for water purification primarily due to high water flux and low degree of fouling. However, the equivalent/apparent pore sizes of as-electrospun ENMs are in microns/submicrons; therefore, the ENMs can only be directly utilized for microfiltration applications. To make regenerated cellulose (RC) ENMs for ultrafiltration applications, atom transfer radical polymerization (ATRP) was studied to graft polymer chains onto the surface of RC nanofibers; specifically, monomers of 2-hydroxyethyl methacrylate (HEMA) and sodium acrylate (AAS) were selected for surface-grafting water-insoluble and water-soluble polymer chains onto RC nanofibers, respectively. With prolonging of the ATRP reaction time, the resulting surface-modified RC ENMs had reduced pore sizes. The water-insoluble poly(HEMA) chains coated the surface of RC nanofibers to make the fibers thicker, thus decreasing the membrane pore size and reducing permeability. On the other hand, the water-soluble poly(AAS) chains did not coat the surface of RC nanofibers; instead, they partially filled the pores to form gel-like structures, which served to decrease the effective pore size, while still providing elevated permeability. The surface-modified RC ENMs were subsequently explored for ultrafiltration of ∼40 nm nanoparticles and ∼10 nm bovine serum albumin (BSA) molecules from water. The results indicated that the HEMA-modified RC membranes could reject/remove more than 95% of the nanoparticles while they could not reject any BSA molecules; in comparison, the AAS-modified RC membranes had complete rejection of the nanoparticles and could even reject ∼58% of the BSA molecules.
静电纺纳米纤维膜（ENMs）由于具有高通量和低污染程度，在水净化方面具有广阔的应用前景。然而，原电纺 ENMs 的等效/表观孔径处于微米/亚微米范围内；因此，ENMs 只能直接用于微滤应用。为了将再生纤维素（RC）ENMs 用于超滤应用，研究了原子转移自由基聚合（ATRP）以将聚合物链接枝到 RC 纳米纤维的表面上；具体而言，选择 2-羟乙基甲基丙烯酸酯（HEMA）和丙烯酸钠（AAS）单体分别用于将水不溶性和水溶性聚合物链接枝到 RC 纳米纤维的表面上。随着 ATRP 反应时间的延长，所得的表面改性 RC ENMs 的孔径减小。不溶性聚（HEMA）链涂覆在 RC 纳米纤维的表面上，使纤维变厚，从而减小膜孔径并降低渗透性。另一方面，水溶性聚（AAS）链没有涂覆在 RC 纳米纤维的表面上；相反，它们部分填充了孔，形成凝胶状结构，从而减小了有效孔径，同时仍提供了较高的渗透性。随后，对表面改性的 RC ENMs 进行了超滤研究，以从水中分离约 40nm 的纳米颗粒和约 10nm 的牛血清白蛋白（BSA）分子。结果表明，HEMA 改性的 RC 膜可以截留/去除超过 95%的纳米颗粒，而不能截留任何 BSA 分子；相比之下，AAS 改性的 RC 膜可以完全截留纳米颗粒，甚至可以截留约 58%的 BSA 分子。
