Block copolymers with two or more chemically distinct and covalently linked blocks that are thermodynamically immiscible will have the propensity to phase separate on the microscopic scale. These phase-separated regions can conform to many interesting periodic structures that have been useful in areas including lithography, optics, and membrane design. Typically, assembled mesoscale structures are limited in long range periodic order in melt and thin film states due to uncontrolled nucleation and growth. Strategic placement of defects can predetermine nucleation sites and limit grain growth, effectively assisting the assembly process. Well-defined long-range order strengthens the photonic response of polymeric materials and is a key factor in successfully implementing block copolymer-based photonic waveguides in visible-light integrated circuits. Here, a substrate is pre-treated with a quasicrystalline-patterned poly(dimethylsiloxane) (PDMS) photoresist using polymer-pen nanolithography. The polymer pen lithography technique is a novel approach to precise, high throughput application of soft materials onto a surface. The PDMS resist is photopolymerized to yield a durable and chemically selective defect architecture intended to influence the self-assembly of a poly(dimethylsiloxane)-<i>block</i>-poly(ethylene-<i>alt</i>-propylene) block copolymer. Structural characteristics of the resulting patten assisted assembly is compared to traditional assembly methods using X-ray scattering and microscopy techniques. Implementation of a pre-patterned defect surface is hypothesized to assist block polymer self-assembly and enhance structure-property expressions in future applications.

Defect patterning for the directed self-assembly of block copolymers using polymer pen nanolithography

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.