# Directing liquid crystalline self-organization of rod-like particles through tunable attractive single tips

## TL;DR

This study demonstrates how localized attractive interactions at particle tips can control the self-organization of rod-like colloids, enabling stabilization of specific liquid crystalline phases and direct phase transitions.

## Contribution

It introduces a method to tune liquid crystalline states of rod-like particles by functionalizing tips with adjustable attractive interactions, supported by experiments and simulations.

## Key findings

- Tip attraction stabilizes smectic over nematic phases
- Strong tip attraction can induce direct isotropic-to-smectic transition
- Functionalization allows rational design of colloidal assemblies

## Abstract

Dispersions of rodlike colloidal particles exhibit a plethora of liquid crystalline states, including nematic, smectic A, smectic B, and columnar phases. This phase behavior can be explained by presuming the predominance of hard-core volume exclusion between the particles. We show here how the self-organization of rodlike colloids can be controlled by introducing a weak and highly localized directional attractive interaction between one of the ends of the particles. This has been performed by functionalizing the tips of filamentous viruses by means of regioselectively grafting fluorescent dyes onto them, resulting in a hydrophobic patch whose attraction can be tuned by varying the number of bound dye molecules. We show, in agreement with our computer simulations, that increasing the single tip attraction stabilizes the smectic phase at the expense of the nematic phase, leaving all other liquid crystalline phases invariant. For a sufficiently strong tip attraction, the nematic state may be suppressed completely to get a direct isotropic liquid-to-smectic phase transition. Our findings provide insights into the rational design of building blocks for functional structures formed at low densities.