Double-network hydrogels with superior self-healing properties using starch reinforcing strategy

Constructing hybrid double network (DN) hydrogels has become an important strategy to prepare strong and tough hydrogels with good self-healing properties for durable usage. However, the recoverable and self-healing efficiencies of DN hydrogels are usually low. We develop a type of hybrid DN hydrogel, which contain the starch network for generating strong dynamic interactions within the gel matrix. The composite gels show tensile strength over 200 kPa with the elastic modulus of ∼29.7 kPa. Gelatinization of cassava starch is a key procedure that can significantly raise mechanical strengths. The healing efficiency of the composite gel gradually increased to as high as 99 % after 24 h at room temperature. This work shows that dynamic physical bonding in hydrogels can be greatly enhanced by a simple starch reinforcing tactic. The combination of naturally abundant starch with hydrophilic polymers provides a general approach to design functional soft materials for applications in various fields.