Novel Elastomer-Dumbbell Functionalized POSS Composites: Thermomechanical and Morphological Properties

Nanocomposites consisting of poly(styrene-b-butadiene-b-styrene) (SBS) and polyhedral oligomeric silsesquioxanes (POSS) were prepared using a solvent dispersion method. Dumbbell-shaped POSS fillers were prepared using diacyl chlorides to bridge the POSS molecules. Infrared spectroscopy confirmed functionalization. Scanning electron microscopy revealed an increase in filler aggregation with concentration, with preferential phase selectivity. Polydispersity increased with filler concentration while d spacing was influenced by phase selectivity and domain-filler compatibility. Functionalized POSS improved thermal stability by imparting restrictions of SBS chain motions. Tensile stress-strain analysis revealed an increase in modulus, yield strength, and strain hardening with filler concentration, while creep deformation decreased and permanent strain increased with POSS content. Storage modulus, loss modulus, and glass transition temperature increased with filler content due to effective SBS-POSS interaction. Nanocomposite properties were influenced by filler concentration, the phase of the filler was dispersed throughout and the length of the alkyl "barbell" on the dumbbell-shaped POSS. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 585-600, 2012