Surface-Functionalized Polystyrene Latexes Using Itaconate-Based\nSurfmers

Abstract

Itaconic acid was\nreadily transformed to a series of amphiphilic\ndiesters via stepwise esterification of itaconic anhydride; the diesters\ncarry one alkyl (cetyl or octyl) group and either a PEG, glyceryl,\nor dopamine segment. These diesters were used as surfmers for the\npreparation of polystyrene (PS) emulsions, with the expectation that\nthe surface of the emulsion particles would carry PEG, glyceryl or\ndopamine units. NMR spectroscopic studies revealed that the surfmers\nwere covalently incorporated into the polystyrene chains; furthermore,\nNMR tube polymerization experiments also confirmed that when the PEG\nsurfmer was used, the PEG segments are indeed present on the surface\nof the emulsion particles. The size of the PEGlyated PS emulsions\nwas readily varied from 35 to 140 nm by changing the mole fraction\nof surfmer used. In the case of the glyceryl and dopamine carrying\nsurfmers, an octyl unit was used as the hydrophobic segment to\nensure appropriate hydrophobic–hydrophilic balance; it was\nnoticed that significantly larger mole fractions of the surfmers were\nrequired (15–20 mol %) to generate stable emulsions with particle\nsizes of about 150 nm. The PS emulsions carrying dopamine units on\nthe surface were found to adhere to glass surfaces; thus suggesting\nthat such “sticky” emulsion particles could be used\nto functionalize different types of surfaces. Finally, itaconate diesters\nbearing cetyl and perfluorooctyl segments were also prepared and shown\nto copolymerize with styrene to generate fluoroalkyl-enriched PS copolymers;\nthese were used to generate hydrophobic coatings, with water contact\nangles of over 120°. Thus, itaconate-based surfmers are readily\naccessible alternatives for the preparation of emulsions with tailored\nsize and surface functionality.