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A lamellar forming poly(styrene-stat-glycidyl methacrylate)-block-polylactide, P(S-s-GMA)-b-PLA, diblock polymer containing the photoacid generator 4-iodophenyldiphenylsulfonium triflate (IST) was heated above its order-disorder transition temperature, TODT, and subsequently irradiated with UV light to kinetically trap the disordered state by acid-catalyzed cross-linking through the reactive GMA units. We demonstrated that IST remained thermally stable over relevant cross-linking temperatures and times allowing for the independent control over both the thermally induced disordering process and the onset of cross-linking, in contrast to related thermal cross-linking agents. Post removal of the PLA component, the photocured samples displayed a high degree of nanoporosity across a broad cross-linking temperature range that extends to at least 75 °C above the TODT. In-situ photocuring during small-angle X-ray scattering revealed that the cross-linking reaction had a minimal effect on the domain structure. Finally, we demonstrated that highly selective ultrafiltration membranes could be fabricated by spin-coating a P(S-s-GMA)-b-PLA diblock polymer containing IST onto a commercial polysulfone support, irradiating with UV light in the disordered state, and removing the sacrificial PLA domains.
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation (DMR-1609459). The authors thank Dr. Thomas Vidil and Dr. Luke Kassekert for helpful discussions and input and Claire Seitzinger and Dr. Steven Weignand for assistance in experimental setup for the in-situ UV SAXS experiments. ±-Lactide was kindly provided by Altasorb, and polysulfone supports were provided by The Dow Chemical Company. Parts of this work were performed in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Use of the Advanced Photon Source (APS) at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, under Contract DE-AC02-06CH11357. SAXS measurements were performed at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the APS, supported by E. I. DuPont de Nemours and Co., The Dow Chemical Company, and Northwestern University. GISAXS measurements were performed at Sector 8 ID-E of the APS.
Copyright © 2019 American Chemical Society.
- block polymer
- nanoporous material
- nanostructured polymers
- order-disorder transition
- ultrafiltration membrane