Kinetics Living polymerization

Key words FT-NIR, kinetics, living polymerization, isobutylene, ethylene oxide, butadiene, anionic polymerization, cationic polymerization... 

Kinetics. Details of the kinetics of polymerization of THF have been reviewed (6,148). There are five main conclusions. (/) Macroions are the principal propagating species in all systems. (2) With stable complex anions, such as PF , SbF , and AsF , the polymerization is living under normal polymerization conditions. When initia tion is fast, kinetics of polymerizations in bulk can be closely approximated by equation 2, where/ is the specific rate constant of propagation /is time [I q is the initiator concentration at t = 0 and [M q, [M and [M are the monomer concentrations at t = 0, at equiHbrium, and at time /, respectively. 

In this chapter, we restrict discussion to approaches based on conventional radical polymerization. Living polymerization processes offer greater scope for controlling polymerization kinetics and the composition and architecture of the resultant polymer. These processes are discussed in Chapter 9. 

In addition to the unique insertion kinetics, the polymerization of a-olefins by the Ni(II) catalysts affords polymers of narrow molecular weight distributions at low temperature. At -10 °C, chain transfer becomes reduced to the extent that polymerizations are living with polydispersities below 1.10 (Table 3) [70], This was... 

Fig. 8. The apparatus for kinetic studies of living polymerizations under an electric field. Reproduced, with permission, from Ise, Hirohara, Makino, and Sakurada J. Phys. Chem. 72, 4543 (1968)...

The alkylaluminum component combined with V(acac)3 has an influence on the kinetic behavior of the propylene polymerization at —78 °C47 82 83). In the polymerization with V(acac)3 and dialkylaluminum monohalide like Al(i-C4H9)2C1, Al(n-C3H7)2C1, A1(C2HS)2C1 or Al(C2H5)2Br, M of polypropylene increased proportionally to the polymerization time, and the polydispersity (M Mj was as narrow as 1.15 0.05 (see Fig. 9). This is the case of living polymerization. As can be seen from Fig. 9, the rate of increase of Mn, i.e. the rate of propagation of living chains as expressed by lvln/(42 t), is influenced by the kind of aluminum component and decreases in the series... 

Assuming that we are dealing with so-called "living" polymerization (in the absence of chain termination in the course of polymerization), the kinetic mechanism of (o-dodecalactam polymerization with instantaneous initiation can be written as... 

Nyrkova, I.A., and Semenov, A.N. "Non-linear scission-recombination kinetics of living polymerization". Eur. Phys. ]. 24,167-183 (2007). 

The molecular mass of the generated macromolecules is most easily predicted for living polymerizations with rapid initiation (see Chap. 5, Sect. 8.1). Somewhat more complicated is the case of systems that, although are not living, at least polymerize without transfer. The number average polymerization degree, P, of the product is a simple function of the mean kinetic chain length, v... 

---