Molecular ordering of nematic liquid crystals in tubular nanopores: Tailoring of optical anisotropy at the nanoscale by polymer pore-surface grafting

TL;DR

This study investigates how polymer grafting on nanopore walls influences the molecular alignment and optical properties of nematic liquid crystals within alumina membranes, revealing tunable anisotropy at the nanoscale.

Contribution

It demonstrates that polymer surface modification can control the molecular ordering and optical anisotropy of liquid crystals confined in nanopores, enabling tailored optical properties.

Findings

Polymer deposition causes inhomogeneous coverage with nanodomains.

Repeated polymer coating enhances negative optical anisotropy.

Molecular ordering varies with surface coverage and pore wall modification.

Abstract

The optical polarimetry technique is used to explore molecular ordering of nematic liquid crystals 5FPFFPP3 embedded in parallel cylindrical channels of alumina membranes with pore walls covered by a SE-1211 polymer film enhancing normal anchoring. A chemical film deposition from organic solution apparently results in inhomogeneous coverage with local islands on the channels walls. Accordingly, a coexistence of differently ordered LC regions (nanodomains), characterized by positive and negative anisotropy, results in a weak effective (average) optical birefringence. Repeated polymer deposition reduces the size of uncovered pore walls regions and thus leads to a strengthening of negative optical anisotropy observed in the experiments.