Silane coupling agents, chemistry

The kinetics of the acid catalyzed hydrolysis of ethoxysilanes has been studied. Each of the silanes that were used had a phenyl or para-substituted phenyl group attached to the silicon atom. This permitted a study of the linear free energy relationships of this reaction. The reaction is of interest because of its role in silane coupling agent chemistry, in the preparation of zinc-rich silicate coatings, in the sol-gel process and in the preparation of silicones in general. 

Sol-gel primers use inorganic or metal-organic precursors (generally aluminum, silicon or titanium alkoxides) whose chemistry is closely related to the silane coupling agents discussed previously. These precursors are dissolved in alcohol, then hydrolyzed by the addition of water ... 

Other aspects of interfacial science and chemistry are examined by Owen and Wool. The former chapter deals with a widely used chemistry to join disparate surfaces, that of silane coupling agents. The latter chapter describes the phenomenon of diffusion at interfaces, which, when it occurs, can yield strong and durable adhesive bonds. Brown s chapter describes the micromechanics at the interface when certain types of diffusive adhesive bonds are broken. The section on surfaces ends with Dillingham s discussion of what can be done to prime surfaces for adhesive bonding. 

The subject of silane chemistry and its interaction with both glass surface and polymer resins have been studied extensively. Since the silane coupling agent for improving the bond quality has first appeared in the literature (Rochow, 1951), a wide variety of organofunctional silanes has been developed, prominently by Plueddemann and coworkers. An early compilation of this subject for epoxy and polyester matrix composites (Plueddemann et al., 1962, Clark and Plueddemann, 1963 Plueddemann, 1974), and more recent reviews on the use of silane agents and... 

The substrate/silane interphase and the silane/matrix interphase are equally important in considering the mechanism of reinforcement by silane coupling agents in composites. The mineral oxide/silane interphase is more well defined than a metal/silane or a silane/matrix interphase. For example, in the case of a metal substrate, surface oxides may dissolve into the silane layer or form a complex. In the case of the silane/matrix interphase, a diffuse boundary layer may exist due to dispersion of physisorbed silanes in the matrix phase or penetration of the matrix resin into chemisorbed silane layers. Many features of the interaction of a silane coupling agent with a polymer matrix are specific to the system, and thus the chemistry of the silane/matrix interphase must be characterized and defined for each system. 

Plueddemann, E.P. (1980) Chemistry of silane coupling agents. Macromol. Monogr., 7, 31-53. 

PG Pape, EP Plueddemann. History of Silane Coupling Agents in Polymer Composites. 192nd Annual Meeting, American Chemical Society, Div. of the History of Chemistry, Anaheim, 1986, Paper No. 30, pp 1-35. 

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