Morphology evolution of functionalized styrene and methyl methacrylate copolymer latex nanoparticles by one-step emulsifier-free emulsion polymerization

Abstract

Evolution of morphology in the latex nanoparticles synthesized by emulsion polymerization methods has been an interesting challenge. Herein, a fast and facile methodology was developed for the synthesis of functionalized latex nanoparticles based on polystyrene (PS) and poly(methyl methacrylate) (PMMA) by one-step emulsifier-free emulsion copolymerization with functional acrylic comonomers. These functional latex nanoparticles display different particle size in the range of 150–1400 nm and morphologies depending on the surface functional groups. Morphological investigation of the functionalized latex nanoparticles by scanning electron microscopy and transmission electron microscopy display that PMMA and PS latex nanoparticles with amide and hydroxyl functionalities have cauliflower like morphology with a non-smooth surface. The PS latex nanoparticles functionalized with epoxy groups have vesicular morphology in colloidal and red blood cell-like morphology in solid state. The PMMA latex nanoparticles containing epoxy and hydroxyl functionalities on the surface and also the PS latex nanoparticles functionalized with amide groups display highly monodispersed spherical morphologies. The porous surface was observed for the spherical PMMA and PS latex nanoparticles functionalized with carboxylic acid groups by using 4,4′-azobis(4-cyanovaleric acid) as the initiator. Different morphologies observed for the functional PS and PMMA latex nanoparticles prepared by one-step emulsifier-free emulsion polymerization are very interesting and have potential applications in drug-delivery, bioimaging, cell-labeling, and chemosensors.