Magnetic, Fluorescent, and Copolymeric Silicone Microspheres

DOI: 10.1002/advs.201500114 acts as its own isolated microreactor, reducing the chance of prepolymer coalescence and aggregation. Additionally, the size and composition of the resultant product are easily adjusted by altering the concentration and choice of precursors in the nebulized solution. The USP preparation of PDMS microspheres uses a simple ultrasonic transducer (1.7 MHz) to generate a mist from a precursor solution that is then swept by an inert gas fl ow through a heated tube (illustrated in Figure S1 in the Supporting Information). A solution of PDMS (Sylgard 184; 2:1 base to accelerator) in hexanes was nebulized using this apparatus and the aerosol carried through a furnace set at 300 °C via an Ar stream (0.4 slpm). The resulting product is collected in EtOH bubblers, washed three times with EtOH (using an ultrasonic bath) followed by centrifugation, and resuspended in hexanes. SEM ( Figure 1 a) of the product shows well-formed microspheres with minimal agglomeration. FTIR of the dried product (Figure 1 b) matches the IR spectrum of PDMS reported in the literature, [ 10,24 ] and Raman mapping (Figure 1 c) confi rms the PDMS signal originates from the microspheres and not from any residual unreacted PDMS or nonspherical cross-linked PDMS. Thermogravimetric analysis (Figure S2, Supporting Information) is consistent with that of bulk PDMS. [ 25 ]