# Controlled Synthesis of Liquid-Crystalline Polymers Under Ambient Conditions by Red-Light-Driven ATRP

## TL;DR

This paper introduces a new method to make liquid-crystalline polymers using red light, which allows precise control and works under normal conditions.

## Contribution

The study introduces red-light-driven ATRP for synthesizing LCPs with precise control and ambient conditions.

## Key findings

- LCPs were synthesized with high monomer conversion and narrow molecular weight distributions.
- Polymer growth was controllable by turning light on and off, and molecular weight affected LC behavior.
- The method works with various monomers and light sources like sunlight and smartphone LEDs.

## Abstract

Red-light-driven
atom transfer radical polymerization
(ATRP) using
methylene blue as a photocatalyst has attracted considerable attention
due to its high efficiency and oxygen tolerance. However, its application
to functional polymers remains unexplored. Here we demonstrate the
synthesis of liquid-crystalline polymers (LCPs) under ambient conditions
using red-light-driven ATRP. Well-controlled polymerizations with
high monomer conversions were achieved within several hours. The polymer
growth could be precisely regulated by alternating the light irradiation
on and off. Molecular weights were tuned by adjusting the polymerization
conditions, affording LCPs with narrow molecular weight distributions.
A clear relationship between molecular weight and LC behavior was
observed. The method was extended to various mesogenic monomers and
polymerizable groups, confirming its broad applicability. Moreover,
controlled polymerization was achieved using accessible light sources
such as sunlight and smartphone LED flashlights. This versatile approach
enables efficient LCP synthesis and facilitates exploration of structure–property
relationships in functional soft materials.