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

Abstract

In this paper, nitrogen-coordinated boroxines are exploited for the fabrication of self-healing and recyclable polymer composites with enhanced mechanical properties. The 3D polymer networks cross-linked with nitrogen-coordinated boroxines are first synthesized through the trimerization of ortho-aminomethyl-phenylboronic acid groups at the terminals of poly(propylene glycol) (PPG) chains, and subsequently, the mechanically robust polymer composites are fabricated by utilizing the complexation of nitrogen-coordinated boroxinecontaining PPG (N-boroxine-PPG) with poly(acrylic acid) (PAA) and hydrogenbonding interactions between them. The N-boroxine-PPG is soft with a tensile strength of 0.19 MPa, whereas the tensile strengths of N-boroxine-PPG/PAA composites can be tailored to range from 1.7 to 12.7 MPa by increasing the PAA contents in the polymer composites. It is revealed that the amine ligands can facilitate the formation and dissociation of nitrogencoordinated boroxines at room temperature. Moreover, the reversibility of nitrogen-coordinated boroxines and hydrogen-bonding interactions enable multiple cycles of healing and recycling of the damaged N-boroxine-PPG/PAA composites. The healed and recycled N-boroxine-PPG/PAA polymer composites regain most of their mechanical strength.

Experimental investigation on self-activated healing performance of thermosetting polyurethane prepared by tungsten (VI) chloride catalyst

“…Materials with polymeric self-healing compositions are ideal for long-term applications since micro-cracks inevitably created during usage and could be repaired without any manual interference [7]. Bao et al [8] employed nitrogen-coordinated boroxines to manufacture polymer composites capable of self-healing and recyclability and enriched mechanical properties. Most studies on self-healing polymers have been done on epoxy resins.…”

Healable and Mechanically Super‐Strong Polymeric Composites Derived from Hydrogen‐Bonded Polymeric Complexes

“…Self‐healing/healable materials with extended service life and enhanced reliability can significantly reduce raw material consumption and contribute in the realization of a sustainable society . Currently, endowing artificial materials with healing function is becoming an important consideration in material design.…”

Reversible adhesives based on acrylate copolymer modified by caffeic acid containing boroxin

“…also prepared shape memory supramolecular gel adhesive with self‐healing properties by using the interaction between phenylboronic acid and catechol. When the N element is introduced into the system, the self‐condensation of phenylboronic acid or the reaction with the diol can be promoted since the N‐B coordination can make cyclic structure stable, which also accelerated and stabilized the formation of boroxine or boronate …”

“…18,19 Therefore, the dynamic covalent bond of boroxine is widely used to prepare to self-healing polymers. [20][21][22][23] Lai et al 22 prepared the PDMS networks containing boroxine with high Young's modulus, which was attributed to the strong and 3D network crosslink via boroxine unit. The group can produce dynamic reversible linkage under hydrothermal driving conditions.…”

“…When the N element is introduced into the system, the self-condensation of phenylboronic acid or the reaction with the diol can be promoted since the N-B coordination can make cyclic structure stable, which also accelerated and stabilized the formation of boroxine or boronate. 20,23 Herein we combine 4-formyl-phenylboronic acid (FBA) with caffeic acid (CA) by dehydration and condensation to prepare a multifunctional vinyl monomer. The functional vinyl monomer is able to conveniently introduce into the main chain of acrylate resin by free radical copolymerization.…”