Hydrophilic Double-Network Polymers that Sustain High Mechanical Modulus under 80% Humidity

Taiki Tominaga; Ken-Ichi Sano; Jun Kikuchi; Hideyuki Mitomo; Kuniharu Ijiro; Yoshihito Osada

doi:10.1021/mz300019m

Hydrophilic Double-Network Polymers that Sustain High Mechanical Modulus under 80% Humidity

ACS Macro Lett. 2012 Mar 20;1(3):432-436. doi: 10.1021/mz300019m. Epub 2012 Mar 9.

Authors

Taiki Tominaga¹, Ken-Ichi Sano¹, Jun Kikuchi², Hideyuki Mitomo^{1

3}, Kuniharu Ijiro^{1

3}, Yoshihito Osada¹

Affiliations

¹ Molecular and System Life Science Unit, RIKEN Advanced Science Institute, Wako, Saitama, Japan.
² RIKEN, Yokohama Institute, Tsurumi, Yokohama, Kanagawa, Japan.
³ Molecular Device Laboratory, Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, Japan.

PMID: 35578517
DOI: 10.1021/mz300019m

Abstract

The effects of water on the mechanical properties of synthetic hydrophilic polymers with double-network (DN) structures were studied under different relative humidities (RH). It was found that they could sustain nearly the same high Young's modulus as dry DN polymers in the RH range 10-80% (water content 3-17 wt %), that is, more than 10² MPa. However, when the RH exceeds 80%, DN polymers abruptly absorb large amounts of water (water content 90 wt %) and transform to a highly water-swollen "gel state" with a decrease in the Young's modulus of 3 orders of magnitude. Spectroscopic analyses revealed that water molecules below RH 80% are strongly bound to hydrophilic moieties with highly restricted mobility; water under such states improves rather than reduces mechanical properties by behaving as a plasticizer. DN polymers capable of sustaining high mechanical properties, even under RH 80%, have potential uses as hydrophilic materials.