Super strong dopamine hydrogels with shape memory and bioinspired actuating behaviours modulated by solvent exchange

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Hydrogels are versatile polymeric networks with applications in soft robotics and actuators.
• Dopamine derivatives offer unique properties like self-adhesion and metal ion coordination.
• Developing stimuli-responsive hydrogels with tunable mechanical properties remains a key challenge.

Purpose of the Study:

• To synthesize and characterize dopamine-containing hydrogels with tunable mechanical strength and shape memory.
• To explore the potential of these hydrogels as bioinspired functional soft actuators.
• To investigate the role of dopamine methacrylamide (DMA) association in hydrogel properties.

Main Methods:

• Copolymerization of dopamine methacrylamide (DMA), N,N-dimethylacrylamide (DMAA), and N,N omino-methylenebisacrylamide (BIS) crosslinker.
• Utilizing water and DMSO as solvents to induce reversible physical crosslinking through DMA association.
• Characterizing hydrogel mechanical properties (tensile strength) and shape memory behavior via solvent exchange.

Main Results:

• Achieved tunable tensile strength in hydrogels ranging from 200 kPa to over 2 MPa.
• Demonstrated rapid shape fixing in water and complete shape recovery in DMSO within minutes.
• Successfully designed functional soft actuators, including responsive tentacles and a 'hydrogel paper' for writing.

Conclusions:

• The reversible DMA association provides a facile method for creating shape memory hydrogels.
• These hydrogels serve as a promising platform for developing advanced, bioinspired soft actuators.
• The approach offers a new strategy for designing functional soft materials by combining mussel-inspired chemistry with solvent-responsive properties.