Amplification of Self-Healing in Polymer Hybrid Materials Using Microstructure Engineering*

‘Self-healing’ (SH) describes the ability of materials to recover functional performance after incurring structural damage. To impart SH ability to engineering polymers promises a path towards reduced waste production and increased functional lifetime of polymer parts. Strategies to realize SH polymer materials encompass the introduction of monomer reservoirs or reversible primary or secondary bond network structures. However, despite the recent progress made in the field of SH polymers, a major challenge remains the realization of SH capability in polymers with sufficiently high modulus (> 1 GPa) to be suitable for engineering applications. This is because the mechanism of SH relies on sufficient chain mobility to enable structure reformation. 

This contribution explores a new templating approach to realize high-modulus polymer hybrid materials with SH ability. The approach comprises the dissolution of linear butyl acrylate/methyl methacrylate (BA/MMA) statistical copolymer filler with SH ability within a BA/MMA copolymer brush particle template structure. The selective increase of the MMA content of the brush P(BA-s-MMA) enables the formation of a rigid (high T_g) matrix while maintaining the solubility of the linear P(BA-s-MMA) (low T_g) filler within the interstitial regions of the brush template. The mobility of the linear SH copolymer across the interstitial regions gives rise to the self-heal ability of the rigid hybrid. This unique combination of stiffness and self-healing capability provides opportunities for applications such as self-healing coatings and photonic materials.