# Inverse design of structural colours in polymeric films with crystallization-induced reversible thermochromism

## TL;DR

The paper introduces a model to predict and design structural colors in polymeric films that change color with temperature.

## Contribution

A predictive model for inverse design of structural colors in bottlebrush block copolymers with thermochromic properties.

## Key findings

- A model links BBCP molecular structures to macroscopic colors using theory and optical frameworks.
- BBCPs with specific chain architectures produce a full color spectrum when synthesized.
- Thermochromism is observed in BBCPs with crystalizable and soft segments, absent in others.

## Abstract

Precisely controlling structural colours in polymeric materials remains a major challenge, with current approaches often relying on trial-and-error synthesis. Here, we develop a colour design model, enabling inverse design of structural colours in bottlebrush block copolymers (BBCPs). The model can quantitatively link BBCP molecular structures to macroscopic colours through the integration of a strong segregation self-consistent field theory model with a multilayer optical framework. We first validate its predictive capability by synthesising and assembling BBCPs with varied chain architectures to produce a full colour spectrum, and then demonstrate its generalisability to other BBCP chemistries. In addition, we observe reversible, nonlinear thermochromism in systems combining a crystalisable block with a soft, low–glass transition temperature segment, while similar BBCPs lacking this pairing show no such response. Our work establishes a predictive platform for designing structurally coloured, thermoresponsive polymeric materials and advances the rational engineering of photonic soft matter.

Precisely controlling structural colours in polymeric materials remains a major challenge. Here, the authors develop a colour design model, enabling inverse design of structural colours in bottlebrush block copolymers.