Field assisted self‐assembly for preferential through thickness (“z‐direction”) alignment of particles and phases by electric, magnetic, and thermal fields using a novel roll‐to‐roll processing line

Abstract

Many functional films including heat spreaders, ultrahigh density information storage systems, capacitors, batteries, and fuel cell membranes require enhanced through thickness properties. In this paper, we describe a design and demonstration of a multipurpose novel film formation process to orient and align functional nanoparticles and polymer phases using external electric, magnetic, and thermal gradient fields. This roll‐to‐roll processing line uses a casting system that deposits liquid film of a monomer and/or polymer solution on to a flexible substrate. Substrate is carried by belt through an electric field zone that can apply DC, AC, or a biased AC to orient the phases and particles in the vertical direction while subjecting it to UV through its built in transparent conductive carrier. To orient magnetic particles, an electromagnet located along the machine may be used. The final tool that is built on this machine is the thermal alignment zone which is designed to apply a “line of heat” oriented transverse to the machine direction at nine different zones. Using this processing line, we are able to reduce the cost of manufacturing by limiting the amount of functional fillers through directional alignment while enhancing the thickness properties. POLYM. ENG. SCI., 55:34–46, 2015. © 2014 Society of Plastics Engineers

Photothermally Directed Assembly of Block Copolymers

“…For a variety of interesting BCP materials, the ODT may not be readily accessible (e.g., the material may degrade before disordering); as a result, the CZA regime was investigated . Annealing during CZA occurs on both the heating and cooling fronts; annealing occurs below T ODT but above the material's glass transition temperature, increasing molecular mobility to induce ordering without passing through a disordered state . In‐plane thermal gradients (on the order of 10–70 °C mm −1 ) generated during CZA were shown to induce weakly aligned BCP morphologies with control over orientation through processing parameters, and provide accelerated kinetics relative to traditional oven thermal annealing at comparable temperatures (Figure b) .…”

Transparent and through thickness conductive polystyrene films using external magnetic fields for “Z” alignment of nickel nanoparticles

“…The solution was cast using a doctor blade with a gap set at 635 µm on a PET substrate carried by the stainless steel belt on the roll-to-roll processing, 43 and the magnetic field was applied when the solution cast film enters in between the two poles of the 2.2 Tesla electromagnet assembled on the R2R line. The solution was cast using a doctor blade with a gap set at 635 µm on a PET substrate carried by the stainless steel belt on the roll-to-roll processing, 43 and the magnetic field was applied when the solution cast film enters in between the two poles of the 2.2 Tesla electromagnet assembled on the R2R line.…”

“…[43][44][45] This roll-to-roll processing line could be used to reduce the cost of manufacturing by limiting the amount of functional fillers through directional alignment leading to "directed percolation" while enhancing the properties in the thickness direction at low filler concentrations. [43][44][45] This roll-to-roll processing line could be used to reduce the cost of manufacturing by limiting the amount of functional fillers through directional alignment leading to "directed percolation" while enhancing the properties in the thickness direction at low filler concentrations.…”

Directed Assembly of Hybrid Nanomaterials and Nanocomposites

“…Electric‐field‐directed assembly provides access to both in‐plane and out‐of‐plane alignment of anisotropic hybrid nanocomposites depending on the placement of electrodes, and the ability to overcome any surface‐induced alignment in the proximity of bulk interfaces . At the smallest scale, discrete hybrid nanomaterials can be oriented and assembled into nanodevices as electrical connections across electrodes.…”