Silane-based coupling

H. Ismail, A.H. Abdullah, and A.A. Bakar, The effects of a silane-based coupling agent on the properties of kenaf core-reinforced high-density polyethylene (HDPE)/soya powder composites. Polym. Plast. Technol. Eng. 49(11), 1095-1100 (2010). 

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. 

In addition to the blend of monomers, composite resins contain fillers. These are typically finely divided quartz or barium silicate glasses, and their function is to provide strength for the fully formulated composite [2]. These fillers are linked to the polymer phase by coupling agents, which are typically silane-based substances [2]. Composite reins are characterized by the absence of a chemical reaction between the filler and the monomer or polymer phase. Also, they show no inherent adhesion to the tooth but instead they have to be bonded to the tooth with bespoke bonding agents. These are discussed in detail in Chapter 5. 

Figure 1. A mechanism for dehydrogenative coupling of silanes, based on a transition-metal silylene complex as an intamediate.

Other strategies for improving clay exfoliation in rigid PU foams include the addition of coupling agents, mainly silane-based (Han et al., 2008 Kim et al., 2008), or processing modifications, in addition to the already mentioned ultrasounds, such as microwave processing (Lorenzetti et al., 2010). 

Sousa, R.A., Reis, R.L., Cunha, A.M., Bevis, M.J., 2003. Coupling of HDPE/hydroxyapatite composites by silane-based methodologies. Journal of Materials Science-Materials in Medicine 14, 475-487. 

Highly stable, readily accessible, and recyclable 2-(2-hydroxyprop-2-yl)cyclohexyl-substituted arylsilanes are applied to the silicon-based coupling reaction (Scheme 3-181). The reaction of this aryl(trialkyl)silanes activated by a mild carbonate with aryl chlorides or tosylates gives the aryl-aryl forming products catalyzed by a nickel catalyst in a highly chemoselective manner. 

---