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Photoreversible Loading and Unloading of Q–Silsesquioxane Dynamic Network Sponges
Author(s) -
Hu Nai–hsuan,
Furgal Joseph Coy
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202010114
Subject(s) - silsesquioxane , materials science , hydrosilylation , solvent , dynamic mechanical analysis , azobenzene , polymer , chemical engineering , irradiation , toluene , polymer chemistry , composite material , organic chemistry , catalysis , chemistry , physics , nuclear physics , engineering
The synthesis and mechanical properties of photoswitchable silsesquioxane/azobenzene hybrid 3D‐polymers (“dynamic sponges”) are presented and discussed. The hybrid is capable of extensive macroscopic movement, and overcomes previously problematic crosslink locking issues. A hydride‐functionalized Q‐type silsesquioxane (Q 8 M 8 H ) is reacted with di‐allyloxyazobenzene using hydrosilylation methods. The properties of the resulting materials are controlled via careful choice of starting material ratios and solvent, leading to gels or films. Both morphologies show pronounced photoresponsive behavior in and on the surfaces of different solvents. Photoactuation is tracked by microscopy, dynamic mechanic analysis, and UV–vis spectroscopy. The gel system has a porous structure similar to a sponge. It undergoes shrinkage in volume by 18.3% in toluene under UV irradiation, and shows excellent recovery to the swollen state after irradiation with visible light. These novel photodynamic materials offer reversible modulus switching from 160 kPa in the swollen state to 500 kPa in the “wrung‐out” sponge. The sponges can engage in uptake and release of a range of substances (i.e., reversible hydrophobic sponging), with overall performance determined by solvent specific quantities such as polarity and size. Such behavior gives these materials high potential for soft robotics applications and great promise as reusable environmental remediators.