Dynamic mechanical analyses of Nafion®/organically modified silicate nanocomposites

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 39; no. 12; pp. 1282 - 1295
• Main Authors: Young, S. K., Mauritz, K. A.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 15-06-2001; Wiley
• Subjects: Applied sciences; Composites; dynamic mechanical relaxations; Exact sciences and technology; Forms of application and semi-finished materials; Nafion; nanocomposites; organically modified silicate; Polymer industry, paints, wood; sol-gel; Technology of polymers; Ionomer; Dimethylsiloxane polymer; Property composition relationship; Molecular structure; Organic silane; Experimental study; Molecular relaxation; Sulfonate copolymer; Tetrafluoroethylene copolymer; Dynamic mechanical properties; Sol gel process; Preparation; Crosslinked polymer; Organic silicate
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.1102

Nafion®/organically modified silicate (ORMOSIL) hybrids were generated via polymer in situ sol–gel copolymerizations of tetraethylorthosilicate (TEOS) with difunctional and trifunctional organoalkoxysilane monomers, and the dynamic mechanical relaxations and thermomechanical stability of the resultant composites were investigated. All ORMOSIL fillers restrict main‐chain and side‐chain mobility. The results suggest that sulfonic acid side chains become entrapped in silicate or ORMOSIL structures that evolve during the in situ sol–gel process. Some but not all of the ORMOSIL combinations display trends in the α or β relaxation temperature with respect to the TEOS comonomer ratio. All of the hybrids have greater high‐temperature thermomechanical stability than the unfilled acid form. There are definite composition trends in the vertical displacement of the storage‐modulus–temperature curves. For some of the semiorganic comonomers, there is a monotonic increase in storage modulus with decreasing comonomer content in the high‐temperature regime, which is understood in terms of a progressive immobilization of the long side chains by progressively more rigid ORMOSIL nanostructures. For other semiorganic comonomers, the high‐temperature plateau shifts upward to a maximum and then shifts downward with decreasing comonomer fraction. In addition to the chemical nature of the imparted nanophases, these molecular motions are expected to influence the transport properties of these novel heterogeneous membranes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1282–1295, 2001