Hydrogel-Coated Polydimethylsiloxane with Reversible Transparency for Advanced Optical Switching

Chenxu Liu ¹, Lin Yang ¹, Yongxiang Sun ¹

⁰Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 1H9, Canada.

Acs Nano +

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February 27, 2025

View abstract on PubMed

Summary

Researchers developed a novel hydrogel system that transitions from opaque in air to transparent in water. This water-responsive material has potential for smart windows, optical encryption, and interactive writing systems.

Area Of Science

Materials Science
Soft Matter Physics
Optoelectronics

Background

Functional soft materials often develop surface wrinkles when hydrated, reducing optical transmittance.
Transparent-in-water yet opaque-in-air materials are rare but valuable for applications like smart windows and information encryption.

Purpose Of The Study

To develop a hydrogel system with reversible optical switching between air and water.
To explore applications in optical encryption, water writing, and energy-efficient windows.

Main Methods

Fabrication of a polyacrylamide layer on polydimethylsiloxane (PDMS).
Characterization of optical transmittance changes upon water-induced swelling.
Micro- and nanostructural analysis to understand the mechanism of optical switching.
Evaluation of performance as a smart window for solar power and temperature regulation.

Main Results

The hydrogel system exhibits a reversible transition from 7.8% transmittance in air to 77.1% in water.
Optical switching is attributed to reduced local surface roughness upon hydrogel swelling.
As a smart window, it reduced solar power transmission by 36% and lowered temperature by 5.09 °C.
Demonstrated potential for optical encryption/decryption and water writing applications.

Conclusions

The hydrogel-on-PDMS system offers a versatile platform for water-responsive smart devices.
This technology presents opportunities in optical encryption, interactive writing, and energy-saving windows.

Keywords:

hydrogel layer nanostructures optical encryption polydimethylsiloxane (PDMS) smart window swelling