Shear Alignment of Diblock Copolymers for Patterning Nanowire Meshes
Metallic nanowire meshes are useful as cheap, flexible alternatives to indium tin oxide – an expensive, brittle material used in transparent conductive electrodes. We have fabricated nanowire meshes over areas up to 2.5 cm2 by: 1) mechanically aligning parallel rows of diblock copolymer (diBCP) microdomains; 2) selectively infiltrating those domains with metallic ions; 3) etching away the diBCP template; 4) sintering to reduce ions to metal nanowires; and, 5) repeating steps 1 – 4 on the same sample at a 90° offset. We aligned parallel rows of polystyrene-b-poly(2-vinylpyridine) [PS(48.5 kDa)-b-P2VP(14.5 kDa)] microdomains by heating above its glass transition temperature (Tg ≈ 100°C), applying mechanical shear pressure (33 kPa) and normal force (13.7 N), and cooling below Tg. DiBCP samples were submerged in aqueous solutions of metallic ions (15 – 40 mM ions; 0.1 – 0.5 M HCl) for 30 – 90 minutes, which coordinate to nitrogen in P2VP. Subsequent ozone-etching and sintering steps yielded parallel nanowires. We aimed to optimize alignment parameters (e.g. shear and normal pressures, alignment duration, and PDMS thickness) to improve the quality, reproducibility, and scalability of meshes. We also investigated metals other than Pt and Au that may be patterned using this technique (Cu, Ag).
- Publication Date:
- OSTI Identifier:
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- DOE Contract Number:
- Resource Type:
- Technical Report
- Research Org:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Org:
- USDOE; Dept. of Homeland Security (DHS) (United States)
- Country of Publication:
- United States
- 77 NANOSCIENCE AND NANOTECHNOLOGY; COPOLYMERS; NANOWIRES; AQUEOUS SOLUTIONS; IONS; ALIGNMENT; POLYSTYRENE; SHEAR; ETCHING; SINTERING; TEMPERATURE RANGE 0273-0400 K; THICKNESS; COOLING; HEATING; FABRICATION; GRIDS; PRESSURE RANGE KILO PA; OPTIMIZATION
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