Tuning Dual-Dynamic Network Materials through Polymer Architectural Features

Dynamic materials are known for their self-healing, adhesive, and shape memory applications. Interpenetrating networks (IPNs) are types of materials that can hold dual-dynamic crosslinkers to show complementary chemical and mechanical properties. There have been a number of research studies exploring the dynamic chemistries involved in IPN materials. Not only the bond type but also the polymer network architecture play an important role in governing IPN material properties. In this study, we show that network architectural features are as much as important as studying the dynamic chemistries using an IPN system with quadrupole hydrogen (H) bonding and thiol-Michael (TM) bonding. This work varied network types, chain lengths, dynamic bond compositions, crosslink densities, and crosslink distributions within a system to explore their effects on the thermomechanical properties. The synergetic effects of H and TM bonds revealed excellent stress relaxation and self-healing at room temperature and elevated temperatures. Increment of chain length and crosslink density enhanced the strength of the materials to as high as 3.5 MPa, while the crosslink distribution boosted the creep resistance under an applied force. Furthermore, complementary H and TM bonding assisted in improving the adhesive properties in these materials to hold up to 2 kg weight with the adhered wood strips.