Polymer Networks Assembled by Host−Guest Inclusion between Adamantyl and β-Cyclodextrin Substituents on Poly(acrylic acid) in Aqueous Solution

Abstract

Polymer networks have been constructed through host-guest inclusion between β-cyclodextrin (β-CD) and 1-(2-aminoethyl)amidoadmantyl (ADen) substituents on poly(acrylic acid) (PAA). The structure of the networks and the host-guest interactions between the β-CD and ADen groups were studied by rheology and 2D 1 H NOESY NMR spectroscopy. The maximum viscosity of the mixture of β-CD substituted PAA (β-CDPAA) and ADen substituted PAA (ADenPAA) occurred at a 1:1 β-CD:ADen substituent ratio which confirmed their binary inclusion. The viscosity of the mixture of the two polymers decreased upon addition of native β-CD due to its ability to compete favorably with the β-CD substituents of β-CDPAA in the inclusion of the ADen substituents of ADenPAA and the consequent disintegration of the polymer network. The rheological properties of the polymer networks were temperature sensitive. In the temperature range 10-35 °C, the storage modulus and the loss modulus obeyed a time-temperature superposition. The horizontal and vertical temperature shift factors, a T and b T , obeyed a simple Arrhenius relationship for which the activation energies were found to be 70.3 ( 0.4 and -2.2 ( 0.1 kJ mol -1 , respectively. 2D 1 H NOESY NMR studies showed the ADen substituent to be included within the native β-CD and β-CD substituent cavities.

Supramolecular Polymeric Materials Containing Cyclodextrins

“…As examples for method 1), when polymers containing guest residues are mixed with polymers carrying CDs, they form gels through cross-linking by hostguest interaction. [37][38][39] As an example for method 2), when acrylamide modified with Ad residue (Ad-AAm) was mixed with acrylamide modified with βCD (βCD-AAm) in water, Ad-AAm was solubilized in water, indicating complex formation with βCD-AAm. The resultant pair of host-guest monomers was terpolymerized with water soluble vinyl monomer in forming a hydrogel.…”

Supramolecular Hydrogels for Regenerative Medicine

“…The cavity of β-CD can include hydrophobic molecules as guests. For example, adamantane can be grafted onto poly(acrylic acid), which can form a complex with poly(acrylic acid) functionalized with β-CD to yield a supramolecular hydrogel [113]. This versatile approach allows the use of different polymers and different guests.…”

Polymers Containing Covalently Bonded and Supramolecularly Attached Cyclodextrins as Side Groups

“…However, for polymers which do not contain highly nucleophilic amino groups, other strategies had to be developed. These include the second frequently applied modification reaction, the formation of amides from monoamino-CDs (18, 22a and b) and poly(carboxylic acid) [26,[42][43][44][45] and its copolymers [46,47]. Guo et al synthesized monoamino-bCD derivatives in which the aminogroups were tethered by alkyl chains of different lengths (13).…”