Copolymerization kinetics of a model siloxane system

✍ Scribed by Stephen E. Rankin; Christopher W. Macosko; Alon V. McCormick

• Book ID: 101269203
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 217 KB
• Volume: 35
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199705)35:7<1293::aid-pola15>3.0.co;2-3

✦ Synopsis

Using 29 Si NMR, we monitor the copolymerization of trimethylethoxysilane and dimethyldiethoxysilane (model compounds for more complex sol-gel copolymer systems) in a batch reactor. Under the chosen conditions, the extents of self-and crosscondensation reactions are readily determined. Using a nonideal polycondensation kinetic model, we show that the copolymerization rate coefficient for a pair of sites of differing functionality is bounded by their homopolymerization rate coefficients, lying closer to the larger one. This reactivity pattern generates a heterogeneous monomer distribution in the copolymerization products.