Preparation, thermal and mechanical properties of POSS epoxy hybrid composites

Abstract

Polyhedral oligomeric silsesquioxanes (POSS) epoxy hybrid composites have attracted much research interest because of their unique structure, versatile synthetic approaches, and changeable properties through molecular tailoring. Octakis(dimethylsiloxypropylglycidyl ether)silsesquioxane and octakis(dimethylsiloxyethylcyclohexenyl epoxide)silsesquioxane were synthesized and cured with 4,4 0 -methylenebis(cyclohexylamine) and 4-methylhexahydrophthalic anhydride to prepare the highly crosslinked hybrid materials. The thermochemical data from DSC analysis and FTIR show that the curing reactions of POSS epoxy are more difficult than diglycidyl ether of bisphenol A (DGEBA) resin because of steric hindrance. The multifunctional structure of POSS can form highly crosslinked network throughout the composites, therefore the polymer main framework is frozen and cannot move freely. Some POSS composites do not show glass transitions and the observed relaxation for other POSS composites is likely due to the motion of tethers between POSS cores. The moduli of POSS composites, which decrease slowly with temperature increasing, are much higher than that of DGEBA resins at high temperatures. Although the coefficients of thermal expansion of POSS composites are larger than that of DGEBA resins at low temperatures, they are less dependent on temperature and relatively low at high temperatures. The unique thermal and mechanical properties of POSS composites make them potential candidates for applications in high temperature and temperature variable environments.

Free-standing, polysilsesquioxane-based inorganic/organic hybrid membranes for gas separations

“…6(b)), implying the incomplete crosslinking reaction for the latter one. In light of the fact that the molar ratio of the primary amine of OAPS to the epoxide ring of LPG64 was 0.28 and 0.63 for LPG/OAPS (90/10) and LPG/OAPS (80/20) membranes, respectively, there may exist some structural limitations on the crosslinking reaction due to the steric hindrance of bulky OAPS entities [42,43].…”

Influence of POSS structure on the fire retardant properties of epoxy hybrid networks

“…polyhedral oligomeric silsesquioxane, as a fire retardant in epoxy networks as some recent work suggested [10][11][12][13][14]. Epoxy-based thermosetting networks are known to have excellent characteristics such as solvent and chemical resistance, low shrinkage on cure, good adhesion to many substrates, good mechanical properties and outstanding electrical insulating properties [15,16].…”

Green Nanocomposites from Renewable Plant Oils and Polyhedral Oligomeric Silsesquioxanes

“…So far, a variety of functional POSS derivatives have been developed. Polymerizable POSS macromers, such as vinyl-functionalized POSS and oxirane-functionalized POSS, have been employed to copolymerize with organic monomers to afford a variety of polymer/POSS nanocomposites [15][16][17][18][19][20][21][22][23][24][25][26][27]. Polymerizable POSSs make a covalent attachment to a polymer matrix possible, and POSS units are well-dispersed in a polymer matrix.…”