Bioinspired modification strategy to improve thermal conductivity of flexible poly(vinyl alcohol)/nanodiamond nanocomposite films for thermal management applications

Polymer nanocomposites with high thermal conductivity (K) have promising prospects in thermal management. However, how to achieve good dispersion and strong interfacial adhesion between nanofillers and polymers, and to obtain optimal K at low filler concentrations remains a challenging subject. Here, bioinspired dopamine chemistry was used to form thin polydopamine (PDA) coatings on the surface of nanodiamond (ND) particles (ND@PDA). A series of nanocomposite films consisting of ND@PDA and poly(vinyl alcohol) (PVA) was fabricated via a facile solution casting technique. PDA with strong adhesion and catechol groups remarkably improved interactions between the ND@PDA and the PVA matrix. DSC and XRD data show that crystallinity of nanocomposites is greatly improved with increasing ND@PDA concentrations. As a result, a significantly high K value of 5.864 W/mK was obtained with filler loadings of 10 wt%, which was about 1780% higher than that of neat PVA. The results show that dopamine chemistry-modified ND effectively suppress the phonon scattering at the matrix-filler interface and facilitate efficient transfer of phonons. Moreover, the incorporation of 10 wt% ND@PDA shows considerable enhancement in mechanical performance (35.38 MPa), volume resistivity (6.088 x 10(15) Omega cm) and thermal stability. These highly thermal conductive and electrical insulating polymer nanocomposites with low filler loadings are expected to achieve a wide range of thermal management applications.