Poly alkenamers

A closely related special case of metathesis is the conversion of cycloalkenes under metathesis conditions, known as ring-opening polymerization or metathesis polymerization (see Section 12.2). Macrocyclic polyenes and polymers, called poly-alkenamers, are formed with high stereoselectivity ... 

The poly (diene) monomeric units always contain a double bond which is either in the main chain or in a substituent. The poly(alkenamers) belong to this class of compound in terms of structure, but not in terms of how they are produced. The poly(alkenamers) are obtained from cycloolefins by metathesis polymerization. 

Poly(alkenamers) are produced by ring-opening polymerization of cycloolefins with metathesis catalysts (see Chapter 19). The industrially used name for this class of compounds is based on a lUPAC nomenclature that has since been superceded. These compounds are classified as poly( 1-alkenylenes) according to present lUPAC nomenclature. Poly(pentenamers) and poly-(octenamers) are presently being developed. 

In the presence of WClg-based catalysts, 3-methyl-l,5-cyclooctadiene formed a randomly substituted poly-alkenamer because the two double bonds in the ring-opening reaction had different reactivities [Eq. (45)]. 

Among the published methods in which calibration curves extend down to 0% C3, the most suitable for copolymers with low C3 content should be that of Corish and Tunnicliffe (17). Spectra must be recorded at high temperature (i.e. on molten samples) to eliminate the effects of C2 crystallinity, which are fairly pronounced on the 6.85 p band, as revealed by comparison with spectra recorded at room temperature. The use of standard copolymers prepared with 14C-labelled propylene is recommended. Studies on this topic are being carried out in our laboratory (84) the results so far achieved both on C2-C3 copolymers of various compositions and on models (hydrogenated poly-methyl alkenamers) indicate that the precision of the analysis is consistently improved by taking into account the half-width of the 6.85 p band (i.e. by correlating the C3 molar fraction to the ratio A7.25m/A6.85m... 

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