Titanium-based coupling agents

Metal-Based Coupling Agents Example of Zirconium and Titanium... 

In primer formulations for adhesive bonding of metals, the coupling agents that are most frequently used are those based on epoxy and amine functionalities. Aqueous solutions of aminosilanes have been successfully used for obtaining stable adhesive bonds between epoxy and steel [10] and epoxy and titanium [11,12], while epoxy functional silanes are preferable for applications involving aluminum substrates [13,14], A simple solution of % epoxy functional silane in water is currently used for field repairs of military aircraft [15] where phosphoric acid anodization would be extremely difficult to carry out, and performance is deemed quite acceptable. 

Although the titanium-based methods are typically stoichiometric, catalytic turnover was achieved in one isolated example with trialkoxysilane reducing agents with titanocene catalysts (Scheme 28) [74], This example (as part of a broader study of enal cyclizations [74,75]) was indeed the first process to demonstrate catalysis in a silane-based aldehyde/alkyne reductive coupling and provided important guidance in the development of the nickel-catalyzed processes that are generally more tolerant of functionality and broader in scope. 

Capow [Kenrich], TM for a series of powdered forms of coupling agents based on titanium, zirconium, or aluminum. 

Coupling agents based on titanium and zirconium have been used to improve adhesive properties between polymers and filler-particles and to treat aluminium alloy for adhesive bonding [16]. Like the silanes, they react with surface hydroxyl groups as shown below, but there is no condensation polymerisation to produce a polymer network at the interface. 

There can be reinforcements added to polymeric matrices such as cellulosic fibers, and fillers such as titanium dioxide incorporated into roll thermoplastics, to improve performance properties or reduce cost bases. These host matrices can include polypropylene, polyethylene, polystyrene, polyamide, and PVC to name a few. In these circumstances, the addition of dispersants and/or coupling agents is needed to attract the more highly polar fibers and fillers to the less polar polymer matrix. These added constituents will form a level of presence (depending upon their inclusion ratio relative to the bulk) at the composite surface which must be considered relative to atmospheric plasma chemistry prescription. 

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