We propose that the role of high concentration
NaOH during the formation of FCDs is most likely as a chemical
activation agent to activate PEG. Under the present reflux
conditions, the activated PEG becomes easy to decompose into
carbon substance and other products. The carbon substance with
active surfaces is probably preferential for the polymerization and
growth of FCDs under the reflux conditions. However, the true role
of NaOH in the formation of FCDs is not clear. A detailed study is
required to understand the mechanism of the FCDs. In comparison
to the synthesis of FCDs reported before, our approach is a facile
and green method, the FCDs were obtained in PEG solution, and no
toxic reagents were used. The synthetic procedure involves none of
the toxic organic solvents, initiators, or surfactants. This ensures
that the as-prepared nanoparticles are nontoxic enabling their use
in biochemistry or biodiagnostics, and so on.