Surface modification and disaggregation of detonation nanodiamond particles with biodegradable polyurethane

Nanodiamond(ND) is one of the most important carbon nanomaterials, which not only has the distinguishing feature of fundamental nanoparticles but also has intrinsic characteristics of diamond. Depending on its extraordinary properties, such as good biocompatibility, low toxicity and mechanical behavior, ND thus has been widely used in a variety of fields. However, pristine ND easily tends to aggregate in the form of micro-sized clusters. Therefore, two different approaches for surface modification of ND with biodegradable polyurethane by chemical of grafting-to and grafting-from are presented herein. The Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analyses (TGA) reveal that polyurethane has been covalently attached to ND surface, and the weight loss is 3.51% and 3.23%, which is equivalent to the grafted rate. Dynamic light scattering, transmission electron microscopic (TEM) and natural sedimentation experiment all demonstrate that modified ND with long PU chains can well disperse in organic solvents and CCD images (Charge Coupled Device Images) illustrate that modified ND render hydrophilic pristine ND good hydrophobic behavior. So ND functionalized with polyurethane broadens a new prospect of application in biomedical science. It is suggested that the polyurethane macromolecules covalently bonded onto the agglomerate surface play an important role on the colloidal stability against aggregation.