Choice of dispersants for the nano-apatite filler of polylactide-matrix composite biomaterial

The aim of this study is to compare de-aggregative ability of common organic dispersants for the acicular nano-apatite crystallite with main composition of calcium hydroxyapatite (HA) as a filler of composite containing polylactide (PLA) matrix. Firstly, the acicular nano-apatite powders with an average length of 70–120 nm were synthesized based on traditional chemical co-precipitation and freeze-drying techniques. Common organic dispersants including tetrahydrofuran, acetone, chloroform, N,N-dimethyl formamide (DMF) and ethanol were then employed to disperse synthetic freeze-dried ultra-fine nano-powders. The observations and weight of sediments showed that nano-apatite suspension dispersed by DMF and ethanol presented homogeneous and stable colloid after vigorly stirred for 24 h and then kept still for same time, respectively. Results of particle measurements and viscosity measurement illuminated that a large number of the nano-apatite particles with an average dimension of 297.86 nm and viscosity of 0.8872 cP in DMF suspension could be dispersed up to 91.28 nm by the DMF dispersant and the DMF dispersant could minimize agglomeration between the apatite ultra-fine nano-powders. DMF is a more effective and appropriate dispersant to disperse the apatite nano-fillers than chloroform, tetrahydrofuran, acetone and ethanol, when the nano-apatite/PLA composite biomaterials were prepared.