Supramolecular Hydrogel Based on pNIPAm Microgels Connected via Host⁻Guest Interactions

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Polymer Science

Background:

• Poly(N-isopropylacrylamide) (pNIPAm) microgels are stimuli-responsive materials.
• Host-guest chemistry enables non-covalent self-assembly.
• Developing advanced hydrogels requires novel crosslinking strategies.

Purpose of the Study:

• To prepare doubly crosslinked supramolecular hydrogels using pNIPAm microgels.
• To investigate the self-assembly mechanism utilizing electrostatic and host-guest interactions.
• To explore the properties and potential applications of these novel hydrogels.

Main Methods:

• Preparation of pNIPAm microgels with a poly(acrylic acid) shell.
• Coating microgels with charged beta-cyclodextrin polymers.
• Utilizing adamantane-substituted dextrans for host-guest crosslinking (beta-cyclodextrin-adamantane inclusion complexes).
• Rheological characterization of the prepared hydrogels.

Main Results:

• Successful preparation of hierarchical hydrogels via non-covalent crosslinking.
• Demonstration of the first doubly crosslinked microgels using host-guest interactions.
• Observation of fast mechanical response to temperature changes.
• Exhibition of fully reversible, temperature-induced gel-sol transitions in the physiological temperature range (37-41 °C).

Conclusions:

• The developed hydrogels possess unique properties due to synergistic shrinking and crosslink dissociation.
• The reversible thermal transitions suggest significant potential for biomedical applications.
• This work presents a novel approach to creating advanced supramolecular hydrogels.