Ring-opening polymerization cycloalkane

It is now well established that ring-opening polymerization of cycloalkanes and bicycloalkenes, initiated with olefin metathesis catalysts, is propagated by metal carbene complexes (1). 

Penelle J. Polymerization of cycloalkanes. In Dubois P, Coulembier O, Raquez J-M, editors. Handbook of Ring-Opening Polymerization. Weinheim, Germany Wiley-VCH 2009. p 329. 

Figure 9 Entropy of polymerization as a function of ring size for unsubstituted lactams °) and cycloalkanes ( ). Reproduced from Sekiguchi, H. In Ring-Opening Polymerizations, Ivin, K. J. Saegusa, T., Eds. Elsevier London, UK, 1984 Vol. 2, Chapter 12, p 809. ...

Figure 13.1 Free-enetgy of polymerization at 25 °C for the ring-opening polymerization of unsubstituted cycloalkanes (CH2), [22].

This Handbook of Ring-Opening Polymerization is intended as a single comprehensive reference covering all main classes of monomers, including heterocyclics, cyclic olefins and alkynes, and cycloalkanes, with special emphasis on the polymerization tools required for the precise control of macromolecular parameters. 

These are used more often than cycloalkanes nevertheless they are far from being conventional monomers . They polymerize either as 1, 2-disub-stituted alkene derivatives [14] (without ring opening) or else the cyclic monomer is split, yielding a macrocycle or a linear chain (metathesis). 

When certain cycloalkanes are used in metathesis reactions, ring-opening metathesis polymerization (ROMP) occurs to form a high molecular weight polymer, as shown with cyclopentene as the starting material. The reaction is driven to completion by relief of strain in the cycloalkene. 

Besides the thermodynamic feasibility, there should also be a kinetic pathway for the ring to open, facilitating polymerization. Cycloalkanes, for example, have no bond in the ring structiire that is prone to attack and thus lack a kinetic pathway. This is in marked contrast to the cyclic monomers such as lactones, lactams, cyclic ethers, acetals, and many other cyclic monomers that have a heteroatom in the ring where a nucleophilic or electrophilic attack by an initiator species can take place to open the ring and initiate polymerization. Both thermodynamic and kinetic factors are thus favorable for these monomers to polymerize (Odian, 1991). 

A third example of a polymeric ligand with pH-sensitive solubility is 97. This ligand was prepared by ring-opening metathesis polymerization of the 1,4,7-triazacyclononane-containing monomer 96 by the chemistry shown in Eq. 40 [132]. This polymer was capable of forming Mn(IV) complexes that oxidize alkenes and cycloalkanes with hydrogen peroxide. This basic polymer s solubility is affected by pH, as is the case with the other polymers 93 and 95 described above. 

Part 2 includes chapters on specific classes of cyclic monomers and their polymerization mechanisms and kinetics, their main (co)polymer architectures and related products, as well as current and future applications. Hence, siloxane-con-taining and sulfur-nitrogen-phosphorus-containing polymers are described in Chapters 3 and 4, respectively, while the polymerization of cyclic depsipeptides, ureas and urethanes, of polyethers and polyoxazolines, and of polyamides are detailed in Chapters 5, 6 and 7, respectively. Chapters 9, 10, 11 and 12 include details of polyesters prepared from either P-lactones, from dilactones, from larger lactones and from polycarbonates, while the polymerization of cycloalkanes is described in Chapter 13. It should be noted that, slightly out of place . Chapter 8 covers the subject of ring-opening metathesis polymerizahon. 

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