Controllable synthesis of high aspect ratio Mg₂B₂O₅ nanowires and their applications in reinforced polyhydroxyalkanoate composites

Highly pure magnesium borate (Mg₂B₂O₅) nanowires with an average diameter of ～ 30 nm, an average length of ～ 15 μm, and a high aspect ratio of ～ 500 have been synthesized on a large scale via a two-step method. MgBO₂(OH) nanowires with high aspect ratios were first prepared via a PVP-assisted hydrothermal technique. Using these nanowires as precursors, single crystalline Mg₂B₂O₅ nanowires were synthesized by post-annealing treatment at a relatively low temperature of 700 ℃. The important effect of the MgBO₂(OH)-Mg₂B₂O₅ conversion process on the morphology of the Mg₂B₂O₅ nanowires was investigated and it was indicated that the recrystallization process plays an important role in the protection of the one-dimensional (1D) nanostructure. Moreover, the rigidity and the toughness of the Mg₂B₂O₅ nanowire-reinforced PHA composites were tremendously improved compared to those of the pure PHA. Our results demonstrate the effectiveness of Mg₂B₂O₅ nanowires for reinforcement applications in polymer composites.