Preparation of polymer-clay nanocomposites using emulsion polymerization : influence of clay modifiers on the final nanocomposites morphology

[摘要] ENGLISH ABSTRACT: Modification of clay surfaces is an essential requirement for the formation of polymerclaynanocomposites. The clay surface can usually be modified by the replacement ofinorganic cations on the clay surface by cationic surfactants. Further, clay has the abilityto adsorb some organic compounds that have specific functional groups, such as sulphateand amides, by the formation of hydrogen bonds between these functional groups andhydroxyl groups of the clay. Therefore a clay surface can be treated using non-cationicorganic compounds.The marn objective of this study was to modify a clay surface usmg2-acrylamido-2-methyl-l-propanesulphonic acid (AMPS), and investigate the interactionoccurring between AMPS and clay. The adsorption behaviour of AMPS was compared toorganic molecules having similar groups namely: Sodium l-allyloxy-2-hydroxypropyl(Cops), N-isopropylacrylamide (NIPA) and Methacryloyloxy (MET). An understandingof the type of interaction between clay and organic modifier is useful in terms ofunderstanding the mechanism of clay exfoliation in emulsion polymerization.The properties and structure of nanocomposites were characterized using SAXS, TEM,DMA, and TGA. The strncture of the nanocomposite was affected by the type of claymodifiers. Nanocomposites prepared using AMPS show an exfoliated structure, whileother nanocomposites, i.e. those prepared using Cops, NTPA, and MET showed structuresbetween intercalated and partially exfoliated. The mechanical and thermal properties ofnanocomposites were found to be strongly dependent on the degree of clay distributionthrough the polymer matrix. The nanocomposites with exfoliated structures were found tohave higher Tg values, improved mechanical prope1ties, and also better thermal stabilitythan nanocomposites with intercalated structures.

[发布机构] Stellenbosch University