Inspired
by inorganic oligomers and their polymerization, we herein
develop a heterogeneous inorganic polymerization tactic that can be
used to prepare a muscle-like hybrid hydrogel by inducing the polymerization
of calcium phosphate oligomers (CPO) onto a polyvinyl alcohol (PVA)
molecular chain network. In this heterogeneous process, the CPO units
bond with PVA molecules via assistance from sodium
alginate (SA), and then gradually polymerize along the organic chains
to form ultrafine hydroxyapatite nanolines with a diameter of ∼1
nm. Because of the well integration of organic and inorganic phases
from the heterogeneous polymerization, the hierarchical structured
hydrogel can exhibit ultratough mechanical properties of ∼17.84
MPa in strength and ∼8.97 kJ m–2 in fracture
energy, which exceed natural muscles and almost synthetic hydrogels.
Moreover, the damaged hydrogel can be repaired readily by adding the
precursors of CPO, PVA, and SA, which can induce in situ re-polymerization. The hydrogel also exhibits muscle-like rotational
motion under aqueous conditions, which can be developed into a water-driven
biomimetic motor. This study indicates that inorganic polymerization
can achieve a novel organic–inorganic integration rather than
conventional organic–inorganic composition, and it provides
a novel tactic for design and manufacture of advanced materials.