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The combination of precision control with wide tunability remains a challenge for the fabrication of porous nanomaterials suitable for studies of nanostructure–behavior relationships. Polymer micelle templates broadly enable porous materials, however micelle equilibration hampers independent pore and wall size control. Persistent micelle templates (PMT) have emerged as a kinetic controlled platform that uniquely decouples the control of pore and wall dimensions. Here, chain exchange is inhibited to preserve a constant template dimension (pore size) despite the shifting equilibrium while materials are added between micelles. Early PMT demonstrations were synthesis intensive with limited 1–1.3× pore size tuning for a given polymer. Here we demonstrate PMT swelling with homopolymer enables 1–3.2× (13.3–41.9 nm) pore size variation while maintaining a monomodal distribution with up to 250 wt% homopolymer, considerably higher than the ∼90 wt% limit found for equilibrating micelles. These swollen PMTs enabled nanomaterial series with constant pore size and precision varied wall-thickness. Kinetic size control here is unexpected since the homopolymer undergoes dynamic exchange between micelles. The solvent selection influenced the time window before homopolymer phase separation, highlighting the importance of considering homopolymer–solvent interactions. This is the first PMT demonstration with wide variation of both the pore and wall dimensions using a single block polymer. Lastly this approach was extended to a 72 kg mol −1 block polymer to enable a wide 50–290 nm range of tunable macropores. Here the use of just two different block polymers and one homopolymer enabled wide ranging pore sizes spanning from 13.3–290 nm (1–22×).
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Single-variable porous nanomaterial series from polymer structure-directing agents
Abstract Block polymer structure-directing agents (SDA) enable the production of porous nanoscale materials. Most strategies rely upon polymer equilibration where diverse morphologies are realized in porous functional materials. This review details how solvent selectivity determines the polymer SDA behaviors, spanning from bulk-type to solution-type. Equilibrating behavior of either type, however, obscures nanostructure cause-and-effect since the resulting sample series convolve multiple spatial variations. Solution-type SDA behaviors include both dynamic and persistent micelles. Persistent micelle templates (PMT) use high solvent selectivity for kinetic entrapment. PMTs enable independent wall thickness control with demonstrated 2 Å precision alterations. Unimodal PMT pore size distributions have spanned from 11.8 to 109 nm and multimodal pore sizes up to 290 nm. The PMT method is simple to validate with diffraction models and is feasible in any laboratory. Finally, recent energy device publications enabled by PMT are reviewed where tailored nanomaterials provide a unique perspective to unambiguously identify nanostructure–property–performance relationships. Graphical abstract
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- Award ID(s):
- 1752615
- PAR ID:
- 10362309
- Publisher / Repository:
- Cambridge University Press (CUP)
- Date Published:
- Journal Name:
- Journal of Materials Research
- Volume:
- 37
- Issue:
- 1
- ISSN:
- 0884-2914
- Page Range / eLocation ID:
- p. 25-42
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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