Organic/Inorganic Hybrid Composites from Cubic Silsesquioxanes

Abstract

A new class of epoxy nanocomposites with completely defined organic/inorganic phases was prepared by reacting octakis(glycidyldimethylsiloxy)octasilsesquioxane [(glydicylMe(2)SiOSiO(1.5))(8)] (OG) with diaminodiphenylmethane (DDM) at various compositional ratios. The effects of reaction curing conditions on nanostructural organization and mechanical properties were explored. A commercial epoxy resin based on the diglycidyl ether of bisphenol A (DGEBA) was used as a reference material throughout these studies. FTIR was used to follow the curing process and to demonstrate that the silsesquioxane structure is preserved during processing. OG/DDM composites possess comparable tensile moduli (E) and fracture toughness (K(IC)) to, and better thermal stabilities than, DGEBA/DDM cured under similar conditions. Dynamic mechanical analysis and model reaction studies suggest that the maximum cross-link density is obtained at N = 0.5 (NH(2):epoxy groups = 0.5) whereas the mechanical properties are maximized at N = 1.0. Digestion of the inorganic core with HF followed by GPC analysis of the resulting organic tether fragments when combined with the model reaction studies confirms that, at N = 0.5, each organic tether connects four cubes, while, at N = 1.0, linear tethers connecting two cubes dominate the network structure. Thus, well-defined nanocomposites with controlled variation of the organic tether architecture can be made and their properties assessed.

Green Nanocomposites from Renewable Plant Oils and Polyhedral Oligomeric Silsesquioxanes

“…Lee and Lichtenhan used macromers of oxirane-functionalized POSS in reaction with diglycidylether of bisphenl-A in order to change the vitrification temperature [28]. Laine et al synthesized two oxirane-functionalized POSSs and prepared POSS nanocomposites with diaminodiphenylmethane as a hardener [29]. Zheng et al investigated the morphology and thermal properties of POSS containing epoxy hybrid [30].…”

High Tg and fast curing epoxy-based anisotropic conductive paste for electronic packaging

“…Generally, the curing agent is mixed with epoxy resin and subsequently heated to elevated temperature to induce the crosslinking reaction, so-called curing reaction [1][2][3][4] . However, curing reaction for most epoxy systems require considerably high temperature (>200 °C) and long curing time, leading to high energy consumption.…”

Thiirane functional spherosilicate as epoxy resin modifier

“…Besides the above mentioned, also very important and broadly explored are epoxy-functional silsesquioxanes and spherosilicates. They can be used as starting material for further transformations and synthesis of new compounds [15] as well as components of epoxy nanocomposites influencing and determining their unique parameters like crystallinity, structure, curing temperatures, mechanical, and thermomechanical properties [16][17][18][19][20].…”

“…Epoxy resins have been subjects of extensive research, because of their broad practical applications and attractive properties [16][17][18][19][20][21][22][23][24]. However, in some applications they suffer from too long curing times or not strong enough adhesion to metals.…”