Preparation and performance of carboxyl modified NdFeB and derived magnetic self-healing PU composites

Abstract

With the rapid development of today’s society, magnetic self-healing materials are widely used in many fields due to their excellent magnetism and self-healing ability. This article presents a magnetic self-healing composite with good mechanical, self-healing and magnetic properties and magnetic drive performance. Tetraethyl orthosilicate (TEOS), silane coupling agent and succinic anhydride (SA) were used for surface modification of NdFeB magnetic particles (MPs) and NdFeB@SiO2-COOH MPs was synthesized. Iron(III) ions were added to the self-polymerization process of the natural small molecule thioctic acid (TA) to form the PTA-Fe prepolymer. PTA-Fe prepolymer, isophorone diisocyanate (IPDI) and polyether amine (PEA) reacted to synthesis PTA-Fe-PU matrix with good self-healing performance at room temperature. The prepared NdFeB@SiO2-COOH MPs was mixed with the self-healing matrix and cured to obtain the magnetic room-temperature self-healing composite MPTA-Fe-PU. The best tensile strength of the composite was 7.31 MPa and the ultimate elongation was 833 %. After the prepared MPTA-Fe-PU sample strip was completely cut, the incision on the surface almost disapeared and the tensile strength recovered to 6.35 MPa after 12 h self-healing at room temperature. The self-healing efficiency was up to 87 %. The highly efficient self-healing properties were mainly derived from the disulfide bonds exchange reaction and iron(III) ion coordination in the matrix.