Fig. 1: Intrinsic radiolabelling strategy.
From: Synthesis of 14C-labelled polystyrene nanoplastics for environmental studies
a Proposed labelling strategy of polystyrene from macromolecule to nanoparticles. (1) Initiator potassium persulfate (KPS) produces water soluble SO4− radical which must first polymerise in the water phase until becoming sufficiently hydrophobic to enter into the organic phase32 to (2) initiation of 14C-styrene radical for the polymerisation, propagation and termination33. Overview of the mechanisms forming: b small 14C-nPS (target 20 nm) with surfactant in the system according to Smith–Ewart–Harkins theory33 for unlabelled nPS; c large 14C-labelled nPS (target 250 nm) in the aqueous phase as per the method of Yamamoto et al.23 for unlabelled nPS. The large red spheres with a blue outer line represent aggregates of solidified smaller nanoparticle monomers. Red carbon atoms are 14C-labelled (i.e. styrene [methylene-14C]); blue indicates the radical initiator (KPS); purple circles are monomer drops; black pins represent surfactant. Transmission electron microscopy images of particles synthesised are displayed to the right of the mechanisms shown in b and c.
