# Dual-Strategy Design of Molecular-Weight-Engineered PEDOT:PSS Complex Films for Enhanced Mechanical Ductility and Environmental Robustness

## TL;DR

This paper introduces a new method to improve the flexibility and durability of conductive materials for wearable electronics.

## Contribution

A dual-strategy combining molecular-weight engineering and hydrogen-bond complexation to enhance PEDOT:PSS performance.

## Key findings

- Hydrogen-bonded PEDOT:PSS/PEO films show 60% elongation at break while maintaining high electrical conductivity.
- Films retain over 30% elongation at break across a wide temperature range and low humidity.
- Antifreezing performance allows 42% elongation at break at -20 °C.

## Abstract

Developing ductile
and environmentally robust conductive materials
is essential for next-generation wearable electronics, particularly
those operating under harsh conditions. Poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate)
(PEDOT:PSS), a hygroscopic intrinsically conducting polymer, offers
high electrical conductivity (σe) and inherent flexibility.
However, its multiscale structural defects significantly limit its
mechanical deformability across diverse environments. Herein, we propose
a dual-strategy design that integrates (1) molecular-weight engineering
and (2) hydrogen-bond-driven polymer complexation, achieved by incorporating
ultrahigh molecular weight (M
w) poly­(ethylene
oxide) (PEO; subzero T
g) into a high-M
w PEDOT:PSS matrix. It enables the construction
of hydrogen-bonded PEDOT:PSS/PEO complex films with enhanced mechanical
ductility and environmental tolerance. Structural characterization
confirms that H-bonds between PSS and PEO improve miscibility. The
involvement of ultrahigh M
w PEO chains
softens the rigid PEDOT:PSS matrix and promotes extensive chain entanglements,
yielding films with elongation at break (εbreak)
around 60% while maintaining a high σe of 100 S·cm–1 at 40 wt % PEO. Notably, the flexible PEO chains
enable hygroscopic PEDOT:PSS/PEO films to retain the εbreak > 30% across a wide temperature range (−20 to 60 °C)
or at low-humidity conditions (RH = 10%). In particular, the PEDOT:PSS/PEO
films exhibit antifreezing performance, retaining εbreak ∼ 42% at −20 °C. These findings demonstrate
a synergistic molecular-weight engineering strategy, combined with
flexible H-bond complexation to produce ductile and environmentally
tolerant conductive films for next-generation wearable electronics.