| Popis: |
Despite the omnipresence in everyday life of fluoropolymers, mainly due to their numerous and attractive applications, further progress in their synthesis is needed. Experimentally, the study of telomers is of great interest, with the aim of better control of the molecular weight of polymers with the use of a transfer agent. The reaction efficiency is quantified by the transfer constant (CnT), which is the ratio of the transfer and propagation rate constants, and thus quantifies the kinetically driven competition between transfer and propagation rates. Nevertheless, it can be difficult to gain access to certain reactions and thus to improve existing reactions further. With the considerable recent advances in computer power, quantum chemical methods are particularly attractive for studying reactions of fluorinated polymers and thus for calculating CnT. Correlating these simulated values with experimental data provides a way to reveal interesting trends, ultimately leading to improved reactions, and this is the topic of this chapter. The procedure for calculating the transfer constant is discussed, and in particular, the transition state theory and calculations involved are considered. To illustrate these concepts, a practical example of the calculation of Ctr for vinylidene fluoride (VDF) with the widely used Gaussian 09 commercial software is described. Finally, some perspectives for improving syntheses are presented. |
