Fig. 5: Formation of ETPTA droplets at the micron and submicron scales by gas-assisted step-emulsification.

a Experimental image of air-ETPTA compound thread pinching synchronously at the step. The high viscosity of ETPTA (64 mPa·s) leads to filament formation, as indicated by the black arrow. Some visible ETPTA microdroplets are marked by red circles, and the magnification of one microdroplet is shown in the lower-right inset. The upper-left inset shows ETPTA “balloon” droplet formation without gas assistance at the same flow rate of ETPTA (\({{{q}}}_{2}\)); no small droplets of ETPTA can be generated in this regime. b Sketch of the flow regime and droplet generation at the step. c UV-cured ETPTA beads taken from the supernatant after being size sorted by sedimentation. Inset: a polydisperse distribution of the ETPTA beads before sedimentation, scale bars stand for 5 μm. d Number density of the size of the UV-cured ETPTA beads before sedimentation. Inset: the volume density of the beads before sedimentation. e SEM image of the UV-cured ETPTA beads taken from the supernatant after sedimentation; the scale bar in the inset represents 1 μm. f Number distribution of the size of the colloidal beads after sedimentation