Shape Memory Hydrogel based on a Hydrophobically-Modified Polyacrylamide (HMPAM)/α-CD Mixture via a Host-Guest...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Shape memory (SM) hydrogels are advanced materials with the ability to recover their original shape when subjected to a stimulus.
• Developing stimuli-responsive hydrogels with efficient shape recovery and reusability remains a key challenge in materials science.

Purpose of the Study:

• To synthesize and characterize a novel thermally sensitive shape memory hydrogel.
• To investigate the mechanism behind the hydrogel's shape memory properties and its thermo-responsive behavior.

Main Methods:

• Block copolymerization of dimethylhexadecyl[2-(dimethylamino)ethylmethacrylate]ammonium bromide (C(16)DMAEMA) and acrylamide (AM) in the presence of α-cyclodextrin (α-CD) and N,N'-methylenebisacrylamide (MBA) crosslinker.
• Characterization using X-ray diffraction (XRD), solid-state (13)C Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), and rheological measurements.
• Cyclic experiments to evaluate shape recovery and reusability.

Main Results:

• The formation of crystalline domains induced by host-guest interactions between α-CD and polymer chains was confirmed.
• These crystalline domains exhibit reversible melting and crystallization, acting as temperature-dependent physical crosslinks.
• Rheological studies showed significant changes in elastic and viscous moduli due to the reversible crosslinking.
• The hydrogel demonstrated excellent shape memory properties, with nearly 100% deformation recovery in cyclic tests and good reusability.

Conclusions:

• A novel thermally sensitive shape memory hydrogel was successfully prepared.
• The reversible crystalline domains induced by host-guest interactions are responsible for the material's shape memory effect.
• The hydrogel exhibits promising properties for applications requiring stimuli-responsive and recoverable materials.