To quantify the kinetics of platelet growth, we then examined the dependence of platelet size and morphology on unimer concentration, seed concentration, and solvent conditions (Fig. ). Platelets were prepared in bulk under various reaction conditions, with sample aliquots removed at predefined time points to fully capture the reaction kinetics. These samples were then characterized by iSCAT (2 µW µm -2 , 637 nm, 900 µs exposure time; see further details in the Experimental Methods section). A minimum of 100 platelets were analyzed at each time point for each condition. As expected, a higher initial unimer concentration leads to faster platelet growth, producing platelets with larger final surface area (Fig. ). A linear dependence of the overall rate constant on unimer concentration was observed with an overall reaction order of 0.41 (Fig. ). This deviation from simple first-order kinetics has been reported previously and attributed to conformational effects on the block copolymer during assembly. We also examined the dependence of platelet formation on seed concentration (0.25 to 1.13 nM), keeping unimer concentration and solvent conditions fixed (Fig. ). As expected, a higher seed concentration produces platelets with smaller final sizes.