COPOLYMERIZATION BEHAVIOR AND STRUCTURE OF STYRENE AND POLYMERIZABLE SURFACTANTS IN 3-COMPONENT CATIONIC MICROEMULSION

The copolymerization and structural properties of the ternary o/w-micr oemulsions formed from water, styrene and (11-(acryloyloxy)undecyl)tri methylammonium bromide or (2-(methacryloyloxy)ethyl)dodecyldimethylamm onium bromide as cationic polymerizable surfactants are investigated. The two surfactants contain the polymerizable group either at the hydr ophobic tail (T-type) or at the hydrophilic head group (H-type) and fo rm micellar structures in aqueous solution. Upon addition of styrene, transparent, globular o/w-microemulsions are formed without any additi on of a cosurfactant. The microemulsions can be polymerized upon gamma -irradiation at room temperature. Copolymers with completely different morphology are obtained. With styrene and the T-type surfactant, very small nanolatex particles are formed similar to microemulsion polymer ization of styrene and nonpolymerizable surfactants. In contrast, copo lymerization of styrene and the H-type surfactant monomer results in t ransparent nanogels with high water content. The structure of the mice lles and o/w-microemulsions before and after polymerization was studie d using small-angle neutron scattering (SANS), while the copolymer str ucture was analyzed using NMR and IR spectroscopy. SANS experiments sh ow that in the water/H-type surfactant/styrene system the overall stru cture of the parent microemulsion is largely preserved whereas in the T-type system distinct changes are observed. Structure models are pres ented which take into account the different proper ties of the resulti ng polymer materials at both a macroscopic and a microscopic length sc ale.