Abstract
Membranes are prepared by self-assembly and casting of 5 and 13 wt% poly(styrene-b-butadiene-b-styrene) (PS-b-PB-b-PS) copolymers solutions in different solvents, followed by immersion in water or ethanol. By controlling the solution-casting gap, porous films of 50 and 1 µm thickness are obtained. A gradient of increasing pore size is generated as the distance from the surface increased. An ordered porous surface layer with continuous nanochannels can be observed. Its formation is investigated, by using time-resolved grazing incident small angle X-ray scattering, electron microscopy, and rheology, suggesting a strong effect of the air-solution interface on the morphology formation. The thin PS-b-PB-b-PS ordered films are modified, by promoting the photolytic addition of thioglycolic acid to the polybutadiene groups, adding chemical functionality and specific transport characteristics on the preformed nanochannels, without sacrificing the membrane morphology. Photomodification increases fivefold the water permeance to around 2 L m(-2) h(-1) bar(-1) , compared to that of the unmodified one. A rejection of 74% is measured for methyl orange in water. The membranes fabrication with tailored nanochannels and chemical functionalities can be demonstrated using relatively lower cost block copolymers. Casting on porous polyacrylonitrile supports makes the membranes even more scalable and competitive in large scale.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1701885 |
| Journal | Small |
| Volume | 14 |
| Issue number | 18 |
| DOIs | |
| State | Published - Oct 4 2017 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledged KAUST grant number(s): 1671 – CRG2
Acknowledgements: This work was sponsored by the King Abdullah University of Science and Technology (KAUST) Grant 1671 – CRG2. The authors thank Christopher Waldron, Nimer Wehbe, and Mohamed Nejib Hedhili for the assistance on the XPS measurements, as well as Alessandro Genovese for the EFTEM and STEM–EELS analysis, and Long Chen for the assistance in the AFM measurements. The authors acknowledge Cornell High Energy Synchrotron Source (CHESS) in USA and Laboratório Nacional de Luz Síncrotron (LNLS) in Brazil for the access to the GISAXS and SAXS synchrotron facilities. The authors thank Florian Meneau and Tiago Araujo Kakile at LNLS for their support at the SAXS1 beamline. CHESS was supported by the National Science Foundation and the National Institutes of Health/National Institute of General Medical Sciences under NSF award DMR-1332208.