Nikos Hadjichristidis, Department of Chemistry, University of Athens, Greece

(hadjichristidis@chem.uoa.gr)

ABSTRACT

Model graft and block-graft co/terpolymers of styrene, isoprene and butadiene with tri-, tetra and hexafunctional branched points, randomly or regularly placed along the backbone, were synthesized using anionic polymerization high vacuum techniques and chlorosilane chemistry. Molecular characterization carried out by SEC (UV and RI detectors), low-angle laser light scattering, differential refractometry and NMR spectroscopy confirmed the high degree of molecular and compositional homogeneity of the synthesized materials. The morphological and mechanical properties of these materials were investigated by TEM, SAXS and mechanical testing. The structure/morphology relationship for graft copolymers may be understood by applying Milner’s model to the constituting miktoarm star. The observed morphology is independent of the functionality of the branch points but the extent of long range order decreases with increasing number of branch points. The strain at break of these materials can greatly exceed those of commercial thermoplastic elastomers (e.g. Kraton and Styroflex). Architecturally induced changes in morphology provide a powerful means to manipulate the mechanical properties of graft copolymers and thus to design novel and more efficient thermoplastic elastomers.