Gelation Based On Host-Guest Interactions Induced By Multi-Functionalized Nanosheets

Host-guest interaction, being reversible and stimuli-responsive, is ideal to be applied to the design of hydrogels. We created a gelation system based on the host-guest interactions between the adamantyl groups and beta-cyclodextrin beta-CD) polymer. N,N,N-trimethyl-1-adamantylammonium hydroxide (TriMAA) cations were attached to the pre-exfoliated alpha-zirconium phosphate (alpha-ZrP) nanosheets by ionic bonding through a displacement reaction with the exfoliating agents. The exfoliated alpha-ZrP nanosheets with adamantyl groups directly or indirectly attached to the surface act as reversible high-functionality crosslinkers within the beta-CD polymer. The gelation occurred at a host-to-guest ratio of 1:10 or 1:5 at room temperature within minutes. The agents used to exfoliate alpha-ZrP can tailor the surface of the resultant oc-ZrP nanosheets and the ionic strength of the system, which directly affects the further gelation results. Plus, the exfoliating agent cations may generate a host-and-guest interaction with the beta-CD polymer as well. This gelation process without covalent bonding formation should help fellow researchers to better understand the gelation system and host-guest interactions.