Modeling the Self-Assembly of Copolymer-Nanoparticle Mixtures Confined between Solid Surfaces

Abstract

Using numerical calculations, we undertake the first morphological studies of mixtures of AB diblocks and nanoparticles that are confined between two hard walls. A complex interplay of entropic and enthalpic interactions drives the nonselective particles to localize at the hard walls and A/B interfaces, causing the mixture to spontaneously self-assemble into particle-decorated lamellae that are oriented perpendicular to the surfaces. The film reveals a periodic array of particle "nanowires" that are separated by the nanoscale polymer domains, yielding a vital material for nanodevice fabrication.

Thin films of complexed block copolymers

“…179 In a theoretical study, Lee et al concluded that confinement of a copolymer nanoparticle mixture could result in stable perpendicular lamellae due to a complex interplay of entropic and enthalpic interactions driving nonselective particles to localize at the hard walls and A-B interfaces. 180 Zhou et al were able to achieve a relatively high loading of trioctylphosphine (TOPO) and polyethylene glycol (PEG) coated CdSe nanoparticles in the microdomains of a PS-b-P2VP diblock copolymer, only slightly effecting the self-assembly, while producing a high particle density. 181 In a combined experimental and theoretical study, it was shown that the location of nanoparticles inside block copolymer domains can be tuned even more accurately by changing the period of a chemically patterned substrate used to guide the perpendicular orientation of lamellar microphases to values slightly higher than the equilibrium period or by adding homopolymer.…”

Self-assembly of nanoparticles at interfaces

“…Recently, Cheyne and Moffit demonstrated the formation of mesoscopic wires and cables via co-assembly of polystyrene-decorated CdSe nanoparticles and a polystyrene-block-poly (ethylene oxide) block copolymer at the water/air interface. 90 Another approach is inspired by the recent theoretical arguments by Balazs and coworkers [91][92][93] that predict that block polymer/nanoparticle mixtures self-organize into hierarchically ordered structures dictated by the size, surface properties and volume fractions of the nanoparticles. Experimentally, Thomas and coworkers found that hydrocarbon-coated gold nanoparticles, with a diameter of 3.5 nm, segregated to the interface between the microdomains of poly(styrene-b-ethylene propylene) (PS-PEP) copolymer, while larger hydrocarbon-coated silica nanoparticles (21.5 nm in diameter) were located at the center of the PEP domains.…”

Conductivity of carbon nanotube polymer composites

“…Thus, with appropriate choice of polymers more structured arrangements with improved percolation of CNTs at low fractions might be possible.. Template-controlled assembly of CNTs is a problem relevant not only to nanocomposites, but to other diverse application areas [6]. Self-organization of inorganic nanoparticles in copolymers have been investigated both experimentally [7] and computationally [8,9] and dispersion of stiff rods, somewhat representative of CNTs, have been investigated in fluids and phase-separating fluid mixtures [10].…”