posted on 2021-08-20, 16:51authored byChao Nan Zhu, Si Yu Zheng, Hao Nan Qiu, Cong Du, Miao Du, Zi Liang Wu, Qiang Zheng
Developing hydrogels with new structures
and extraordinary performances
is fundamental and mission-critical for the advancements of gel materials.
Here, we report a class of tough supramolecular hydrogels facilely
prepared by polymerizing methacrylic acid precursor solution in the
presence of hexadecyltrimethylammonium chloride micelles. After swelling
the as-prepared hydrogels in water, strong polyelectrolyte/surfactant
complexes (PESCs) are formed between the weakly charged polymer chains
and oppositely charged surfactants, serving as the physical cross-links
of the gel matrix. The equilibrated hydrogels are transparent with
a water content of 50–85 wt % and possess excellent mechanical
properties, with a tensile breaking stress of 0.1–5 MPa, a
breaking strain of 600–1200%, and Young’s modulus of
1–70 MPa. Typical yielding is observed at a small tensile strain
of ∼10%, followed by forced elastic deformation of the hydrogels,
which are in a glassy state due to the reduced segmental mobility
of the matrix highly cross-linked by PESCs. The plastic-like mechanical
properties of hydrogels could be well tuned by pH, temperature, and
ionic strength that influence the ionization of polymer chains and
the strength of PESCs. These dynamic behaviors render the hydrogels
with self-recovery and shape-memory properties. Furthermore, the nanosized
hydrophobic pockets within the hydrogels afford the capacity of loading
functional hydrophobic molecules with promising applications as fluorescent
materials and drug delivery systems. The design principle and strategy
should be extended to other systems, including biomacromolecules and
lipids, toward broad applications in biomedical and engineering fields.