Lewis bases polar monomers

Dispersancy Incorporating dispersancy into OCP VI improvers is considerably more difficult than the case with free-radical solution chemistry, as described for PMAs. Direct copolymerization of the preferred N- or O-containing monomers is not practical since these Lewis bases will complex, and thus poison, the acidic Ziegler-Natta catalysts. The only option identified so far is to use an amount of catalyst in excess of that complexed by the polar monomer, as described for N-vinylimidazole [24] or V-vinyl succinimide [25]. 

Polymerizations of polar monomers, like acrylic and methacrylic esters with alkyllithium initiators, yield the greatest amount of steric control. Almost all isotactic poly(methyl methacrylate) foims at low temperatures. Addition of Lewis bases such as ethers or amines reduces the degree of isotactic placement. Depending upon the temperature, atactic or syndiotactic polymers form. Also, butyllithium in heptane yields an isotactic poly(A, A -dibutylacrylamide) at room temperature. ... 

Additives that coordinate to Al perturb the polymerization kinetics in toluene. For instance, THF and cyclohexanone compete e-CL for coordination to aluminum (18), which decreases the propagation rate and may even inhibit polymerization. In contrast, kinetics is faster upon addition of a Lewis base, such as 4-picoline (19), because the coordination of this Lewis base onto the Al atom polarizes the metal-alkoxide bond and facilitates the monomer insertion. Although the reactivity of the active sites is increased, the extent of transesterification reactions is reduced, more likely for steric reasons. 

MA complexes formed, 212 polar vinyl monomer complexes, 416 Lewis bases, MA reactions, 509 Lignin, MA condensation, 505 (+)-Limonene, MA Diels-Alder adduct, 157 Ljnoleic acid... 

Similar to the monomers capable of anionic ROP, those able to undergo cationic ROP have polarized bonds represented by Y-X, where Y (atom or functional group) has a lone electron pair so that it can act as Lewis base to react with... 

Epoxide monomers readily undergo cationic polymerization whereby chain propagation is based on the attack of a carbocation on the negatively polarized oxygen of the oxirane (XL). Chain initiation is either by another cation or by a strong electrophile, such as a Lewis acid (BF3) or a protonic Brpnsted acid. The process is illustrated in the reaction mechanism (Scheme 6.40). ... 

The mechanisms of ionic and coordination polymerizations are more complex and are not as clearly understood as those of free radical polymerization. Here, we will briefly highlight the essential features of these mechanisms, and more details will be given in Chapter 7. Initiation of ionic polymerization usually involves the transfer of an ion or an electron to or from the monomer. Many monomers can polymerize by more than one mechanism, but the most appropriate polymerization mechanism for each monomer is related to the polarity of the monomers and the Lewis acid-base strength of the ion formed. 

Continue the development toward commercialization of the new class of postmetallocene catalysts based on transition metal (Ti, Zr, Hf, V,. ..) complexes without Cp, but with imino-carboxylate and imino-amido ligands and sometimes with a neutral Lewis acid acting as a co-catalyst (Makio and Fujita 2009 Makio et al. 2011 Ivanchev et al. 2012). These systems are capable efficiently polymerized monomers containing polar group. Furthermore, different reactions are possible, e.g., anionic polymerization, ring-opening polymerization, or polycondensation. 

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