Huang et al. [61] constructed a hydrogel with superabsorbent property using
sodium alginate (SA), β-CD, and graphene oxide (GO). When the initial concentration of adsorbed dye methylene blue was 50 mg/L and adsorption time 3 h, the
adsorption ratio was 84.98%, and the adsorption capacity could reach 133.24 mg/L.
The proportion of methylene blue adsorbed by the composite hydrogel after six
cycles of regeneration remained above 82%. The adsorption mechanism could be the
own to the synergistic non-covalent interaction (hydrogen bonding, electrostatic
interaction, and π-π interaction) between the hydrogel and methylene blue. Similarly,
Sheibani et al. [62] constructed supramolecular nanohydrogel composites using
β-CD, bentonite, and citric acid by in situ intercalation and melt intercalation. Due
to the presence of the free carboxylic acid in the hydrogel, the hydrogel also had
good adsorption properties for methylene blue.
17.3.3.2 Removal of Metal Ions
The high toxicity and enrichment of heavy metal ions made it particularly urgent to
eliminate them effectively. Huang et al. [63] used microwave cross-linking method
and synthesized a novel biodegradable hydrogel by copolymerization of β-CD,
acrylic acid, and methylene acrylamide. The hydrogel exhibited a typical threedimensional network structure and had a very good adsorption property toward
heavy metal ions Cd
2+ , Pb
2+ , and Cu
2+ . Similarly, the biocomposite hydrogels
constructed by Das et al. [64] using triethylenetetramine, β-CD, and glutaraldehyde
also had a good adsorption property toward Hg
2+ .
17.3.4 Smart Materials
Smart materials with optimal dynamic structures possess an irreplaceable position in
both practical applications and scientific researches. Taking advantage of the reversible property of supramolecular interactions, hydrogels based on CD hosts and
corresponding guests always possess unique environmental stimuli (such as
UV/Vis and NIR light, pressure, pH, temperature, redox, electric and magnetic,
and enzyme) responsibility, thus allowing for the creation of adaptive and intelligent
materials.
17.3.4.1 Photosensitive Materials
Harada et al. [65] constructed a supramolecular hydrogel based on α-CD- and
azobenzene-modified acrylamide derivatives. Upon the irradiation of UV or Vis
light, a reversible macroscopic deformation could be observed directly. When
irradiated with 365 nm UV light, a curved hydrogel was formed; when the hydrogel
was irradiated with 450 nm visible light from the same direction, the deformation of
the hydrogel immediately recovered (Fig. 16). This phenomenon could be accused
of the binding and dissociation of α-CD and azobenzene in the supramolecular
hydrogel. The contraction and expansion of the supramolecular hydrogel based on
the host-guest interaction is very similar to the motion of muscle fiber. The above
498
Q. Zhao et al.
sodium alginate (SA), β-CD, and graphene oxide (GO). When the initial concentration of adsorbed dye methylene blue was 50 mg/L and adsorption time 3 h, the
adsorption ratio was 84.98%, and the adsorption capacity could reach 133.24 mg/L.
The proportion of methylene blue adsorbed by the composite hydrogel after six
cycles of regeneration remained above 82%. The adsorption mechanism could be the
own to the synergistic non-covalent interaction (hydrogen bonding, electrostatic
interaction, and π-π interaction) between the hydrogel and methylene blue. Similarly,
Sheibani et al. [62] constructed supramolecular nanohydrogel composites using
β-CD, bentonite, and citric acid by in situ intercalation and melt intercalation. Due
to the presence of the free carboxylic acid in the hydrogel, the hydrogel also had
good adsorption properties for methylene blue.
17.3.3.2 Removal of Metal Ions
The high toxicity and enrichment of heavy metal ions made it particularly urgent to
eliminate them effectively. Huang et al. [63] used microwave cross-linking method
and synthesized a novel biodegradable hydrogel by copolymerization of β-CD,
acrylic acid, and methylene acrylamide. The hydrogel exhibited a typical threedimensional network structure and had a very good adsorption property toward
heavy metal ions Cd
2+ , Pb
2+ , and Cu
2+ . Similarly, the biocomposite hydrogels
constructed by Das et al. [64] using triethylenetetramine, β-CD, and glutaraldehyde
also had a good adsorption property toward Hg
2+ .
17.3.4 Smart Materials
Smart materials with optimal dynamic structures possess an irreplaceable position in
both practical applications and scientific researches. Taking advantage of the reversible property of supramolecular interactions, hydrogels based on CD hosts and
corresponding guests always possess unique environmental stimuli (such as
UV/Vis and NIR light, pressure, pH, temperature, redox, electric and magnetic,
and enzyme) responsibility, thus allowing for the creation of adaptive and intelligent
materials.
17.3.4.1 Photosensitive Materials
Harada et al. [65] constructed a supramolecular hydrogel based on α-CD- and
azobenzene-modified acrylamide derivatives. Upon the irradiation of UV or Vis
light, a reversible macroscopic deformation could be observed directly. When
irradiated with 365 nm UV light, a curved hydrogel was formed; when the hydrogel
was irradiated with 450 nm visible light from the same direction, the deformation of
the hydrogel immediately recovered (Fig. 16). This phenomenon could be accused
of the binding and dissociation of α-CD and azobenzene in the supramolecular
hydrogel. The contraction and expansion of the supramolecular hydrogel based on
the host-guest interaction is very similar to the motion of muscle fiber. The above
498
Q. Zhao et al.