around 95%. In addition, these materials also showed interesting proximity and
humidity sensitivity.
Many functional particles could also be modified easily by CDs; therefore, we
prepared a series of functional self-healing composites using this strategy. For
example, electromagnetic wave-absorbing coating is a kind of important modern
materials for military and civil applications. However, coatings show a high risk
of being damaged because of their specific application on the surface. The scratches
on the coatings not only lead to the reduction of their lifetime but also to the
deterioration of wave-absorbing properties. In order to enhance the coating lifetime,
a kind of self-healing electromagnetic wave-absorbing coating was developed
by introducing β-CD-Fc interactions between absorbing fillers (Fe 3 O 4 ) and poly
(hydroxyethyl-methacrylate-butyl acrylate) (PHEMA-BA) matrix. These p(HEMABA)-Fe 3 O 4 coating exhibited good absorption performances over a broadband range
of radar band since the wave-absorbing capacity of Fe 3 O 4 [42]. More importantly,
after being damaged, the cracks on this coating can be healed completely with the aid
of small amounts of water. Simultaneously, the electromagnetic absorbing ability
of the coating is restored along with the self-healing process. Using TiO 2 instead
of Fe 3 O 4 , a UV-blocking coating with self-healing ability was developed. TiO 2
particles endowed excellent blocking properties to the coating, and host-guest
interaction between particles and polymer matrix served as healing motif
[43]. Using similar mechanism, we also prepared a kind of reusable xerogel
containing quantum dots with high fluorescence retention [44].
It was found that sufficient polymer chains mobility, a small amount of water, and
high inclusion constant of host-guest interactions were essential to the self-healing
process for this kind of composites [45].
22.4 SMPs and SHPs Based on CD-Guest Interactions
Over the past decade, SHPs have attracted increasing attention because they offer
enormous possibilities to improve the reliability of man-made materials. Encouraging
progress in the field of SHPs has been achieved. However, damage with high degree of
deformation is hard to be healed since fracture surfaces cannot autonomously come
together into need closure for healing. Addressing this problem, a new concept that
uses shape memory effect to assist the self-healing process has been explored [46–51].
It is a challenge to prepare materials that have both shape memory and selfhealing properties since the structural requirements of the two types of polymers are
in conflict. SHPs require high chain mobility, while SMPs need a permanent network
restricting chain motion. It is good way to solve this problem through introduction of
two kinds of supramolecular interactions into materials.
For example, Harada et al. explored two different kind of host-guest ICs of β-CD
with adamantane (Ad) and Fc to bind polymers together to form a supramolecular
hydrogel (β-CD-Ad-Fc gel). Both host-guest interactions contributed to the selfhealing, whereas the redox-responsive β-CD-Fc complexes acted as switches to
retain and release the deformation in the shape memory test [52].
596
S. Zhang et al.
humidity sensitivity.
Many functional particles could also be modified easily by CDs; therefore, we
prepared a series of functional self-healing composites using this strategy. For
example, electromagnetic wave-absorbing coating is a kind of important modern
materials for military and civil applications. However, coatings show a high risk
of being damaged because of their specific application on the surface. The scratches
on the coatings not only lead to the reduction of their lifetime but also to the
deterioration of wave-absorbing properties. In order to enhance the coating lifetime,
a kind of self-healing electromagnetic wave-absorbing coating was developed
by introducing β-CD-Fc interactions between absorbing fillers (Fe 3 O 4 ) and poly
(hydroxyethyl-methacrylate-butyl acrylate) (PHEMA-BA) matrix. These p(HEMABA)-Fe 3 O 4 coating exhibited good absorption performances over a broadband range
of radar band since the wave-absorbing capacity of Fe 3 O 4 [42]. More importantly,
after being damaged, the cracks on this coating can be healed completely with the aid
of small amounts of water. Simultaneously, the electromagnetic absorbing ability
of the coating is restored along with the self-healing process. Using TiO 2 instead
of Fe 3 O 4 , a UV-blocking coating with self-healing ability was developed. TiO 2
particles endowed excellent blocking properties to the coating, and host-guest
interaction between particles and polymer matrix served as healing motif
[43]. Using similar mechanism, we also prepared a kind of reusable xerogel
containing quantum dots with high fluorescence retention [44].
It was found that sufficient polymer chains mobility, a small amount of water, and
high inclusion constant of host-guest interactions were essential to the self-healing
process for this kind of composites [45].
22.4 SMPs and SHPs Based on CD-Guest Interactions
Over the past decade, SHPs have attracted increasing attention because they offer
enormous possibilities to improve the reliability of man-made materials. Encouraging
progress in the field of SHPs has been achieved. However, damage with high degree of
deformation is hard to be healed since fracture surfaces cannot autonomously come
together into need closure for healing. Addressing this problem, a new concept that
uses shape memory effect to assist the self-healing process has been explored [46–51].
It is a challenge to prepare materials that have both shape memory and selfhealing properties since the structural requirements of the two types of polymers are
in conflict. SHPs require high chain mobility, while SMPs need a permanent network
restricting chain motion. It is good way to solve this problem through introduction of
two kinds of supramolecular interactions into materials.
For example, Harada et al. explored two different kind of host-guest ICs of β-CD
with adamantane (Ad) and Fc to bind polymers together to form a supramolecular
hydrogel (β-CD-Ad-Fc gel). Both host-guest interactions contributed to the selfhealing, whereas the redox-responsive β-CD-Fc complexes acted as switches to
retain and release the deformation in the shape memory test [52].
596
S. Zhang et al.