Effects of Surfactant and Ionic Concentration on Properties of Dual Physical Crosslinking Self-Healing Hydrogels by Hydrophobic Association and Ionic Interactions
Dual crosslinking network hydrogels fabricated non-covalent interactions could afford both excellent mechanical properties and tolerable self-healing performances. Although a range of hydrogels that constructed by hydrophobic associated interaction (HAI) or/and Fe(Ⅲ) ionic interactions have been reported, as far as we known, there was little progress in the case of influence controlled by surfactant types and Fe(Ⅲ) contents on the mechanical and self-healing properties. Herein, in this study, two kinds of dual crosslinking hydrogels based on acrylic acid (AA) and stearyl methacrylate (SMA) were fabricated by using sodium dodecyl sulfate (SDS) and polyvinyl alcohol (PVA) as physical crosslinking points respectively, in which PAA was as the hydrophilic part and PSMA was the hydrophobic part, and ionic interaction of Fe(Ⅲ) ions (Fe3+) combined carboxylic groups (-COO-) of PAA as second crosslinking point. Mechanical properties, self-healing and self-recover performances of the prepared hydrogels and their influencing factors were investigated. The mechanical properties of the two hydrogels increased with higher Fe3+ contents and reached a maximum at 0.3 mol% of Fe3+, while increased gradually with the AA contents. The hydrogels showed self-healing properties with recoverable mechanical values after healing for 24 h. Moreover, the hydrogels also showed around 90% of self-recovery properties. The hydrogels formed PVA as surfactant (HPAA-Fe3+@PVA) showed higher mechanical properties but lower self-healing and self-recovery efficiencies, compared with the SDS associated hydrogel (HPAA-Fe3+@SDS), because of the PVA macromolecules with longer chains increasing the chain entanglement. These results showed that the mechanical properties, self-healing and self-recover performances could be regulated by changing the surfactant types and compositions of AA and Fe3+ of the hydrogels.