Silicone Boronates Reversibly Crosslink Using Lewis Acid– Lewis Base Amine Complexes

Abstract

Silicone elastomers are normally thermosets, which are not readily recycled or repurposed. The few examples of thermoplastic silicone elastomers depend on reversible covalent and non-covalent molecular interactions. It is demonstrated that amine-boronate complex formation provides a simple and flexible route to reversible crosslinked silicones. A variety of network structures were prepared by use of terminal and pendantly functionalised silicone boronates and amines. The crosslink density was quantified using a combination of Shore-hardness measurements, swelling, and rheological analyses. Stress induced by compressive force could be relieved through dynamic B-N bond reformation at 60 °C. Materials could be fully disassembled through introduction of n-butylamine and successfully reformed upon removal of the monofunctional amine by evaporation.

Polysiloxane‐Based Autonomic Self‐Healing Elastomers Obtained through Dynamic Boronic Ester Bonds Prepared by Thiol–Ene “Click” Chemistry

“…Self‐healing, which describes the ability of artificial systems to repair their damage spontaneously, is an especially interesting property of these materials . Endowing polysiloxane‐based materials with superior properties, such as self‐healing, could greatly expand their applications . Various efforts have been made to explore novel self‐healing systems in polymer or materials science .…”

Functional Polymeric Materials Based on Main‐Group Elements

“…In ar apidly developing area, researchers are now taking advantage of dative interactions between LAs and LBs to generate new supramolecular materials.A lthough much less explored to date than H-bonding,m etal-ligand interaction, or p-p stacking, LA-LB interactions have the potential benefit that the strength of the interaction can be readily tuned through simple substituent variation. [110] Thenetworks varied from soft gels to brittle solids depending on the cross-link density.M ore recently,aphysical blend of dithienylborane-containing polystyrene (PS) and ditelechelic PDMS with pyridyl groups at the chain termini was not only rendered completely miscible due to the LA-LB interactions, but also showed the typical thermomechanical and selfhealing properties of asupramolecular transient network (56, Figure 15, left). [2a, 104b,108] One application lies in the formation of transient polymer networks.…”

Synthesis of borosiloxane/polybenzoxazine hybrids as highly efficient and environmentally friendly flame retardant materials

“…We think that a reasonable explanation is the coordination of B atoms and N atoms. Many articles have reported the coordination between B and N . This coordination effect increases the cross‐linking density.…”