Nanostructured tricontinuous block polymers allow for the preparation of single-component materials that combine multiple properties. We demonstrate the synthesis of a mesoporous material from the selective orthogonal etching of a microphase-separated tricontinuous block polymer precursor. Using the synthetic approach of polymerization-induced microphase separation (PIMS), divinylbenzene (DVB) is polymerized from a mixture of poly(isoprene) (PI) and poly(lactide) (PLA) macro-chain transfer agents. In the PIMS process in situ cross-linking by the DVB arrests structural coarsening, resulting in a disordered block polymer morphology that we posit exhibits three nonintersecting continuous domains. Selective etching of the PI domains by olefin cross metathesis and PLA domains by hydrolytic degradation produces a mesoporous polymer with two independent pore networks arising from the different etch mechanisms.
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The authors thank Dr. Yanzhao Wang, Dr. Michael Larsen, and Dr. Thomas Vidil for helpful discussions, Sujay Chopade for DMTA assistance, Dr. Hanseung Lee and Chris Frethem for SEM assistance, and Altasorb for the generous donation of lactide. This work was supported by the National Science Foundation (DMR-1609459). S.A.S. thanks the University of Minnesota (UMN) for the Louise T. Dosdall Fellowship. The Hitachi SU8320 SEM was provided by NSF MRI DMR-1229263. Parts of this work were carried out in the Characterization Facility, UMN, which receives partial support from NSF through the MRSEC program. Portions of this work were performed at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) located at Sector 5 of the Advanced Photon Source (APS). DND-CAT is supported by Northwestern University, E.I. DuPont de Nemours & Co., and The Dow Chemical Company. This research used resources of the APS, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. Data were collected using an instrument funded by the NSF under Award Number 0960140.
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