Dynamic Iminoboronate‐Based Boroxine Chemistry for the Design of Ambient Humidity‐Sensitive Self‐Healing Polymers

Abstract

Developing intrinsic self-healing polymeric materials is of great interest nowadays to extend material lifetime and/or prevent the replacement of damaged pieces. Spontaneously humidity-sensitive healable polymer network built around dynamic covalent B-O bonds was templated by using iminoboronate-based boroxine derivatives. Taking advantage of the dynamic boroxine/boronic acid equilibrium and iminoboronate chemistry, it is possible to construct polymeric materials able to self-heal without requiring any energy-demanding external activation. Interestingly, this novel family of iminoboronate adduct-based materials can be readily produced by a relatively simple and straightforward synthesis between boronic acid and diamine-based compounds, paving the way to coatings that are self-healable at ambient humidity.

How to Design a Self‐Healing Polymer: General Concepts of Dynamic Covalent Bonds and Their Application for Intrinsic Healable Materials

“…Even though the most networks utilize diols to form the boronate esters, recent developments also demonstrate the possibility to apply random copolymers with single alcohol groups within the functional side chains . Due to the fact that these bonds are so versatile, some new polymeric materials combine this concept with other reversible covalent bonds, for example, disulfides, in order to obtain multistimuli‐responsive networks . Another interesting concept was presented by Nakahata et al and involves boronate esters as reversible crosslinks in combination with rotaxanes to achieve a combination of physical and chemical approaches toward self‐healing materials …”

Room‐Temperature Self‐Healing and Recyclable Tough Polymer Composites Using Nitrogen‐Coordinated Boroxines

“…Dynamic boronate/boronic ester bonds have been successfully employed for the fabrication of various self‐healing/healable materials by mixing polymeric boronic acids with polymeric diols . Boroxines are the six‐membered cyclotrimeric dehydration products of organoboronic acids and can produce tripodal molecular architectures . In comparison to boronate/boronic esters, boroxines can increase the cross‐linking density and are suitable for the fabrication of mechanically enhanced self‐healing/healable polymer composites.…”

Advances in intrinsic self-healing polyurethanes and related composites

“…15 Recovery of the PU properties aer damage was possible using appropriate choice of disulde diols and heating at 80 C. [63][64][65] Comparatively, diselenide -Se-Sewas used similarly to disul-de bonds in PUs and showed better healing efficiently than its sulde counterpart thank to the faster reaction exchange of selenium thermo-reversible bond. 66…”