Poly(ε-caprolactone)-grafted polydopamine particles for biocomposites with near-infrared light triggered self-healing ability

- Poly(ε-caprolactone) were covalently grafted onto polydopamine particles by in-situ polymerization.
- The modified polydopamine particles dispersed homogeneously in polymer matrix.
- The mechanical properties of composites significantly improved by the incorporation of fillers.
- The composites showed near-infrared light response and fast optical healing ability.

Polydopamine particles (PDAPs) were used as fillers for construction of multifunctional composites with poly(ε-caprolactone) (PCL) as matrix. To improve the dispersion of PDAPs in matrix and interfacial compatibility in the composites, PCL was firstly grafted onto PDAPs by in-situ ring-opening polymerization of ε-caprolactone. The successful grafting of PCL chains on PDAPs, as evidenced by the FT-IR, elemental analysis, electron microscope and dispersion tests, has greatly improved the dispersion state and interfacial adhesion between hydrophilic PDAPs and hydrophobic PCL, thus resulted in increased degree of crystallinity, and significantly improved modulus and yield strength of PCL. The photothermal effect of PDAPs have also endowed the composites with good photothermal conversion ability. The temperature of composites could rapidly rise up to the melting temperature of polymer upon exposure to near-infrared light, and thus allowed fast optical healing and fully recovered mechanical properties of the composites upon damage based on a melting-recrystallization mechanism.

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