Fig. 2: The nanoparticle segregation mechanism.

a–d Influence of oxygen inhibition on the segregation thickness. Cross-sectional SEM images of samples photocured under an irradiance of 0.4 mW cm⁻² with different conditions: (a) on FEP in air, (b) on FEP placed in a glovebox for 1 min, (c) on FEP placed in a glovebox for 24 h, and (d) on PDMS placed in a glovebox for 24 h. e Schematic illustration showing the cured and uncured regions during photopolymerization. The nanoparticles are omitted in the illustration for visual clarity. f Optical microscopy images showing the thicknesses of the cured region under different irradiation times. g Schematic of the segregation mechanism resulting from oxygen inhibition. The photonic ink contains 15% v/v silica (128 nm) and 1% w/v TPO. Irradiance is 0.4 mW cm⁻² for (a–d) and 2.0 mW cm⁻² for (f). Scale bar, 2 μm in (a–d) and 20 μm in (f).