Poly(vinylamine) microgel-dextran composite hydrogels: characterisation; properties and pH-triggered degradation

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Developing advanced hydrogels with tunable properties is crucial for various applications.
• Microgel (MG) particles offer unique characteristics for creating complex material networks.
• Oxidized dextran (Dexox) presents potential as a cross-linking agent in biomaterials.

Purpose of the Study:

• To investigate the formation and characterization of novel composite hydrogels.
• To explore the triggered degradation of these hydrogels under acidic conditions.
• To assess the impact of component ratios on gel properties like ductility and modulus.

Main Methods:

• Synthesis of cationic poly(vinylamine-co-bis(ethyl vinylamine) ether) (PVAM-BEVAME) microgel (MG) particles.
• Composite hydrogel formation via imine bond cross-linking between MG particles and partially oxidized dextran (Dexox).
• Rheological analysis to determine storage modulus (G') and yield strain; investigation of pH-triggered degradation.

Main Results:

• Composite hydrogels exhibited an elastically effective network with high G' and low tanδ.
• G' increased exponentially with the mass ratio (MR) of Dexox to MG.
• Yield strains increased with MR, reaching up to 130%, indicating enhanced ductility.
• pH-triggered degradation was demonstrated via imine bond cleavage in acidic conditions.

Conclusions:

• The novel PVAM MG/aldehyde mixtures form ductile and versatile colloidal gels.
• This method provides a new route to increase the ductility of hydrogels containing microgel particles.
• The findings suggest potential for these materials in applications requiring adaptable mechanical properties.