Rory McFarland, Matthew Rimpler
Dion Rivera (Chemistry)
When introduced into an aqueous solution of potassium bromide within a well-defined concentration range, poly(diallyl ammonium chloride) (PDADMAC) and poly(sodium-4-styrene sulfonate) (PSS) polyelectrolytes can form a biphasic state known as a complex coacervate. The coacervate divides into low polyelectrolyte concentration (lean) and high polyelectrolyte concentration (dense) phases. While many researchers have proposed these complex coacervates can provide unique environments for chemical reactions the number of practical examples is limited. Research presented here employs a novel use of the Stöber synthesis to create silica nanoparticles using tetra ethoxy silane and 3-aminopropyl triethoxy silane within the complex coacervate environment. These reactions were controlled by the molecular weight of the PSS, using 70,000 and 1,000,000 mean molecular weights. The system is characterized with attenuated total internal reflection Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Differences in the molecular weight of the PSS used give rise to different mechanisms for silica particle formation. Higher molecular weight PSS leads to production of silica particles within the coacervate environment while the lower molecular weight PSS leads to silica formation in a separate solid phase. The molecular weight of the PSS also influences the amount of silane reagent required for the synthesis of the silica particles.
Keywords: coacervate, nanoenvironment, polymer