skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Shear Alignment of Diblock Copolymers for Patterning Nanowire Meshes

Abstract

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 cm 2 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 (T g ≈ 100°C), applying mechanical shear pressure (33 kPa) and normal force (13.7 N), and cooling below T g. 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 techniquemore » (Cu, Ag).« less

Authors:
 [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE; Dept. of Homeland Security (DHS) (United States)
OSTI Identifier:
1325871
Report Number(s):
LLNL-TR-702645
TRN: US1700012
DOE Contract Number:
AC52-07NA27344
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Gustafson, Kyle T. Shear Alignment of Diblock Copolymers for Patterning Nanowire Meshes. United States: N. p., 2016. Web. doi:10.2172/1325871.
Gustafson, Kyle T. Shear Alignment of Diblock Copolymers for Patterning Nanowire Meshes. United States. doi:10.2172/1325871.
Gustafson, Kyle T. 2016. "Shear Alignment of Diblock Copolymers for Patterning Nanowire Meshes". United States. doi:10.2172/1325871. https://www.osti.gov/servlets/purl/1325871.
@article{osti_1325871,
title = {Shear Alignment of Diblock Copolymers for Patterning Nanowire Meshes},
author = {Gustafson, Kyle T.},
abstractNote = {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).},
doi = {10.2172/1325871},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 9
}

Technical Report:

Save / Share:
  • The structure and mechanical properties of a series of polymer blends and block copolymers comprised of medium cis 1,4-polybutadiene and 99% 1,2-polybutadiene have been investigated. Thermal properties (DSC) were determined at two levels of radiation crosslinking and for various sample preparation procedures (solvent and thermal history). Dynamic mechanical spectra (3.5 Hz) were measured over temperature range from 180 to 310K. Transmission electron microscopy was also used for establishing the number phases and the domain size and geometry in the heterogeneous materials. Stress-strain curves were determined for the various samples as a function of crosslink density and casting solvent. Equilibrium swellingmore » ratios were measured for each specimen at the same radiation dose in a good solvent. Swelling values were also obtained in a series of solvents for the parent homopolymers and for a diblock copolymer containing 45% 1,2 polybutadiene.« less
  • The goal of this project was to use molecular simulation to quantify the impact of additives on the onset and structure of bicontinuous phases in linear diblock copolymers (DBC). The focus was on understanding how additives with selective affinity for a given block will distribute and perturb the structure of complex bicontinuous phases (like gyroid, double diamond, and plumbers nightmare whose minority component block forms two interweaving 3D networks) in DBCs; it was hypothesized that a suitable choice of additive type, size, affinity, and concentration may suppress or stabilize a particular bicontinuous phase. The ultimate goal in this line ofmore » investigation is to elucidate the rational design of the optimal additive for which the composition range of stability of a particular bicontinuous phase is maximized. Ours are the first published simulation studies to report on the formation of the gyroid phase in DBC melts and of other bicontinuous phases in DBC-modified by homopolymer. The following tasks were carried out: (i) simulation of bicontinuous phases of pure DBCs via both on-lattice Monte Carlo simulations and continuum-space Monte Carlo and molecular dynamics simulations, (ii) determination of the effect of selective additives (homopolymer) of different sizes on such bicontinuous phases, and (iii) development of novel Monte Carlo methods to map out reliable phase diagrams and improve ergodic sampling; in particular, optimized expanded-ensemble techniques for measuring free-energies and for chemical potential equilibration.« less
  • The authors report neutron reflectivity data on (poly)styrene-(poly)ethylene oxide (PS-PEO) diblock copolymers adsorbed onto quartz from the selective solvent cyclohexane (a non-solvent for PEO and a poor solvent for PS). The PEO ``anchor block`` adsorbs strongly to form a thin layer on the quartz substrate, while the deuterated PS chains dangle into the solvent. They find that under static conditions the density profile of the PS block in a poor solvent can be well described by a Schultz function which is indicative of a polymer ``mushroom.`` Furthermore, they have studied the same system under shear at shear rates from 0--400s{supmore » {minus}1}. They find that there is a dramatic increase in the thickness of the PS layer under shear in cyclohexane and that the relaxation time from the shear-on profile back to the static profile is on the order of several days.« less
  • No abstract prepared.
  • Small-angle X-ray scattering is used to examine quantitatively the distribution of lamellar orientation in shear aligned diblocks as a function of strain amplitude at constant shear duration, frequency, and temperature. At all strains, predominantly perpendicular alignment is observed with some parallel alignment. Also, there is a small amount of transverse alignment. This suggests that alignment by shear occurs at the expense of intermediate alignments followed by reducing transverse alignment. Increased strain at constant time increases the sharpness of the distribution of perpendicular alignment.