Cycloolefins, polymerization

Acyclic olefins act as chain scission agents in cycloolefin polymerization hence, they are employed as molecular weight regulators. Equations (48)-(50) illustrate the sequence by which chain scission is achieved ... 

The following important implications, which bear directly on the nature of the cycloolefin polymerization, have precipitated out of our understanding of the basic properties of the olefin metathesis reaction. 

Gas Chromatography Data. Under the testing conditions used in the GLC analyses it is apparent that the resolution decreases with an increase in temperature. Thus, in Figures 3-7 a tendency of peak broadening is noticed for the higher molecular weight components. Nevertheless, the data are adequate to support an important feature of this work— namely, that this cycloolefin polymerization is reversible. 

The results above support four basic features, characteristic of cycloolefin polymerization ... 

Many experimental data are known confirming that olefin metathesis (including cycloolefin polymerization) proceeds via carbene intermediates. 

Subjects specifically excluded are cycloolefin polymerizations catalyzed by naked nickel catalysts, palladium-catalyzed ethylene/carbon monoxide alternating copolymerizations, metathesis polymerizations of cyclic olefins, and diene polymerizations... 

After Kaminsky, Brintzinger, and Ewen discovered homogeneous metallocene/ methylaluminoxane (MAO) catalysts for stereospecific a-olefin polymerizatiOTi (for reviews on olefin polymerization, see [13-21]), the first report [22, 23] rai addition cycloolefin polymerization without ROMP appeared. This stimulated a great interest in these polymers and in catalysts for cycloolefin polymerization (Fig. 1). Cycloolefins such as cyclopentene, cyclooctene, and norbomene can be polymerized via addition (Fig. 2). Polycycloolefins by metallocenes are difficult to process due to their high melting points and their low solubility in common organic solvents. However, metallocenes allow the synthesis of cyclic olefin copolymers (COC), especially of cyclopentene and norbomene with ethene or propene, which represent a new class of thermoplastic amorphous materials (Scheme 1) [24, 25]. 

Kaminsky W, Boggioni L, Tritto I (2012) Cycloolefin polymerization. In Matyjaszewski K, Moller M (eds) Polymer science a comprehensive reference, vol 3. Elsevier, Amsterdam, p843... 

Cycloolefin polymerization to polymers with high melting points. 

Due to their ready availability and excellent catalytic properties, this type of catalyst has been extensively used in cycloolelin polymerization for several decades, resulting in important industrial applications such as manufacture of hydrocarbon resins [3, 17, 18], They are used mainly in homogeneous systems with adequate solvents but also heterogeneous catalysts are very active and promote cycloolefin polymerization to different reaction products, depending on the operation conditions. Generally, they are unicomponent, binary, ternary and multi-component catalytic systems and their final composition is strongly dependent on the nature and quality of the solvent, the reaction conditions and the monomer type and structure [1],... 

There are several types of Ziegler-Natta and ROMP catalysts employed for cycloolefin polymerization, the majority of them being derived from transition metal salts and organometallic compounds [4-7]. These types are grouped into unicomponent, binary, ternary, and multicomponent catalytic systems as a function of the presence or absence of the organometallic cocatalyst or other additives, each of them being differentiated on the catalyst composition and selectivity toward vinylic or ring-opened polymerization. 

A wide variety of binary catalysts of both Ziegler-Natta and ROMP type, consisting of group IV-VII transition metal salts associated with organometallic compounds, have been used in cycloolefin polymerization to manufacture high molecular weight vinylic and ring-opened polymers [4-7]. The activity and selectivity of these catalytic systems depend mainly on the nature of the transition metal and the structure of cycloolefin. 

---