Microparticle synthesis and characterization
PFC-MPs were synthesized using a T-shaped polydimethylsiloxane (PDMS) droplet generator as previously described.[16]Briefly, using oil (span80, Sigma Aldrich, cat# 1338-43-8) as a continuous phase in the two side channels and polymer solution as the dispersed phase in the middle channel, we produced a steady stream of homogenous PFC- MPs. These MPs were passed through a glass tube and polymerized using the photoinitiator Lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP,0.1wt% in distilled water, Sigma-Aldrich, cat# 85073-19-4) included in the polymer phase, under the irradiation of a lamp (600-700 nm). The composition of MPs was characterized via X-ray photoelectron spectroscopy (XPS) with a scanning monochromated Al Kα (117.40 eV; 25.0 W; spot size, 100 μm). The take-off angle between the sample surface and analyzer was 45.0°, and the X-ray beam collected C1s, N1s, F1s, and O1s elemental information. We also tested the MPs using thermogravimetric analysis (TGA) to study their thermal stability. 5 mg of PFC- MPs were weighed and placed in an open pan (platinum 100 µL) attached to a microbalance (TGA550, TA Instruments). The sample was heated at 10 °C.min-1 from 25 to 700 °C under dry nitrogen in standard mode with a ramp test type.