Slime-inspired crosslinked polysiloxanes networks based on reversible borate-hydroxyl complexes

Boron-containing compounds are often used to construct networks in various research fields and industrial applications. Although borate-crosslinked poly(vinyl alcohol) (PVA) hydrogels and famous toy-product slime have achieved success in the market, there is still a lack of alignment between this success and the understanding of the structure of borate-hydroxyl complexes. Elastomers based on borate-hydroxyl complexes have not yet gained enough attention due to their poor mechanical properties. In this study, hydroxyl-modified polysiloxanes (HS-X) of four different grafting degrees was simply crosslinked by sodium tetraborate (SB) to prepare a novel polydimethylsiloxane (PDMS) elastomer based on borate-hydroxyl complex. The final products showed excellent thermodynamic stability over the tested temperature range. By simply changing the input amount of borate, the rheological and mechanical properties of the elastomers varied widely. Hot-pressing has been proven to be an efficient way to recycle the products and did not cause any decrease in the mechanical properties. Inspired by two common products, slime and PVA hydrogel, the present study was able to reproduce the previous success of borate-hydroxyl complexes to polysiloxanes system. It also provided a new approach for the preparation of novel elastomers based on dynamic reversible covalent bonds.