Designing block copolymer architectures for targeted membrane performance

Abstract
Using a combination of block copolymer self-assembly and non-solvent induced phase separation, isoporous ultrafiltration membranes were fabricated from four poly(isoprene-b-styrene-b-4-vinylpyridine) triblock terpolymers with similar block volume fractions but varying in total molar mass from 43 kg/mol to 115 kg/mol to systematically study the effect of polymer size on membrane structure. Small-angle X-ray scattering was used to probe terpolymer solution structure in the dope. All four triblocks displayed solution scattering patterns consistent with a body-centered cubic morphology. After membrane formation, structures were characterized using a combination of scanning electron microscopy and filtration performance tests. Membrane pore densities that ranged from 4.53 × 1014 to 1.48 × 1015 pores/m 2 were observed, which are the highest pore densities yet reported for membranes using self-assembly and non-solvent induced phase separation. Hydraulic permeabilities ranging from 24 to 850 L m-2 h-1 bar-1 and pore diameters ranging from 7 to 36 nm were determined from permeation and rejection experiments. Both the hydraulic permeability and pore size increased with increasing molar mass of the parent terpolymer. The combination of polymer characterization and membrane transport tests described here demonstrates the ability to rationally design macromolecular structures to target specific performance characteristics in block copolymer derived ultrafiltration membranes. © 2013 Elsevier Ltd. All rights reserved.

Citation
Dorin RM, Phillip WA, Sai H, Werner J, Elimelech M, et al. (2014) Designing block copolymer architectures for targeted membrane performance. Polymer 55: 347–353. Available: http://dx.doi.org/10.1016/j.polymer.2013.09.038.

Acknowledgements
This publication is based on work supported by award No. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST). R.M.D. acknowledges support from the NSF Graduate Research Fellowship Program (GRFP). H.S. acknowledges funding by the NSF single investigator award (DMR-1104773). This work made use of the Cornell Center for Materials Research Shared Facilities, which are supported through the NSF MRSEC program (DMR-1120296) and the Cornell High Energy Synchrotron Source (CHESS), which is supported by the NSF 82 NIH/NIGMS via NSF award DMR-0936384, and MacCHESS supported by NIGMS award GM-103485. We thank Prof. E.M.V. Hoek and M. Pendergast for helpful discussions, and J. Weidman for SEM cross-sectional analysis of the ISV43 membrane.

Publisher
Elsevier BV

Journal
Polymer

DOI
10.1016/j.polymer.2013.09.038

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