The polystyrene chains were installed
at the lower rim of a resorcinarene-based
cavitand via reversible addition–fragmentation (RAFT) polymerization
to form a four-armed star-shaped polymer. A star-shaped polystyrene-functionalized
supramolecular capsule was prepared through the coordination-driven
self-assembly of the four-armed start-shaped polymer with silver ions.
The eight-armed start-shaped supramolecular capsule encapsulated 4,4′-diacetoxybiphenyl
as did a cavitand-based self-assembled capsule. A DOSY measurement
indicated that the eight-armed star-shaped polymer was twice as large
as the four-armed star-shaped polymer. The solution behaviors of these
compounds resulted in a difference in their zero-shear viscosities.
The repeating guest units of poly‐(R)‐2 were selectively encapsulated by the self‐assembled capsule poly‐1 possessing eight polymer side chains to form the supramolecular graft polymer (poly‐1)n⋅poly‐(R)‐2. The encapsulation of the guest units was confirmed by 1H NMR spectroscopy and the DOSY technique. The hydrodynamic radius of the graft polymer structure was greatly increased upon the complexation of poly‐1. The supramolecular graft polymer (poly‐1)n⋅poly‐(R)‐2 was stably formed in the 1:1 host–guest ratio, which increased the glass transition temperature by more than 10 °C compared to that of poly‐1. AFM visualized that (poly‐1)n⋅poly‐(R)‐2 formed the networked structure on mica. The (poly‐1)n⋅poly‐(R)‐2 gelled in 1,1,2,2‐tetrachloroethane, which led to fabrication of distinct viscoelastic materials that demonstrated self‐healing behavior in a tensile test.
The repeating guest units of poly‐(R)‐2 were selectively encapsulated by the self‐assembled capsule poly‐1 possessing eight polymer side chains to form the supramolecular graft polymer (poly‐1)n⋅poly‐(R)‐2. The encapsulation of the guest units was confirmed by 1H NMR spectroscopy and the DOSY technique. The hydrodynamic radius of the graft polymer structure was greatly increased upon the complexation of poly‐1. The supramolecular graft polymer (poly‐1)n⋅poly‐(R)‐2 was stably formed in the 1:1 host–guest ratio, which increased the glass transition temperature by more than 10 °C compared to that of poly‐1. AFM visualized that (poly‐1)n⋅poly‐(R)‐2 formed the networked structure on mica. The (poly‐1)n⋅poly‐(R)‐2 gelled in 1,1,2,2‐tetrachloroethane, which led to fabrication of distinct viscoelastic materials that demonstrated self‐healing behavior in a tensile test.
We report a new synthetic method to construct supramolecular A 8 B n (n = 1, 2, 4) miktoarm star copolymers by host-guest complexation between a resorcinarene-based coordination capsule possessing eight polystyrene chains and 4,4-diacetoxybiphenyl guest molecules that retain one, two or four polymethyl acrylate chains. The formation of the supramolecular A 8 B n (n = 1, 2, 4) miktoarm star copolymers was confirmed by dynamic light scattering (DLS), sizeexclusion chromatography (SEC), and diffusion-ordered NMR spectroscopy (DOSY). Differential scanning calorimetry (DSC) measurements revealed that the miktoarm copolymers were phase-separated in the bulk. The micro-Brownian motion of the A 8 B 4 structure was markedly enhanced in the bulk due to a weak segregation interaction between the immiscible arms.
A resorcinarene is a synthetic macrocycle comprising four resorcinol molecules covalently linked by methylene bridges. The interannular bridges produce a cavitand, which possesses a bowl-shaped structure. We have developed supramolecular capsules formed through Ag(I) and Cu(I) coordination-driven self-assembly of cavitands possessing 2,2’-bipyridyl arms at the upper rim. The self-assembled capsules accommodate various molecular guests and supramolecular assemblies possessing acetoxy groups. The host-guest chemistry of the molecular capsules is applied to fabricate supramolecular polymers. This account describes the recent developments in supramolecular chemistry of resorcinarene-based coordination capsules and describes the brief history of resorcinarene-based capsules and related capsules.
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