Time-Resolved Small-Angle X-ray Scattering Studies during Aqueous Emulsion Polymerization

The persulfate-initiated aqueous emulsion polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) is studied by time-resolved small-angle X-ray scattering (SAXS) at 60 °C using a stirrable reaction cell. TFEMA was preferred to styrene because it offers much greater contrast relative water, which essential for sufficient temporal resolution. evolution in particle size monitored both situ SAXS and ex DLS the absence or presence an anionic surfactant (sodium dodecyl sulfate, SDS). Post-mortem studies confirmed formation well-defined spherical latexes, with volume-average diameters 353 ± 9 nm 68 4 being obtained surfactant-free SDS formulations, respectively. 1H NMR spectroscopy equivalent laboratory-scale formulations indicated conversions 99% within 80 min 93% Comparable kinetics are observed experiments syntheses, nucleation occurring after approximately 6 each case. After nucleation, patterns fitted hard sphere model determine growth formulations. Moreover, enables identification three main intervals (I, II, III) that during surfactant. These consistent those solution conductivity optical microscopy studies. Significant differences between observed, providing useful insights into mechanism polymerization.