Self-healing hydrogel based on surfactant-free hydrophobic association
Self-healing hydrogels are attractive for a variety of applications including coatings. A paper describes the facile preparation of an autonomous self-healing hydrogel comprising surfactant-free hydrophobic associations.
The hydrogel comprised a copolymer of benzyl methacrylate (B), octadecyl methacrylate (O), and methacrylic acid (MA). The hydrogels were prepared via a controlled dehydration procedure to achieve the formation of strong intermolecular hydrophobic associations of the octadecyl groups above a critical polymer concentration.
Fractured hydrogels heal within 30 min
Fractured hydrogels healed within 30 min without any external intervention. Increasing hydrogel polymer content from 31 wt % to 39 wt % resulted in a threefold increase in the shear modulus and 50% reduction of the relaxation time. Addition of 4 mM NaCl to a hydrogel of 31 wt % polymer content resulted in 2.5 times longer relaxation time and 24% decrease in shear modulus. The hydrogels swelled up water by up to four times its weight, which corroborates the robustness of the hydrophobic association crosslinks. The bulk properties of the hydrogels are discussed in terms of the hydrophobic associations of the O-groups and the electrostatic interaction of the MA-groups in the polymer chains.
The study is published in: Applied Polymer Science, Volume 134, Issue 19, 15 May 2017
