Degradation of Unsaturated Polymers and ADMET Polymerization

Watson and Wagener [95] reported a tandem ADMET polymerization/ hydrogenation approach to acetoxy-end-functionalized telechelic polyethylene. DCD was polymerized in the presence of 9-decenyl acetate to form the corresponding di-ester-functionalized homo-telechelic polymer. The crude unsaturated polymer was intimately mixed with silica gel and exposed to 120 psi of H2 at 90 °C. The silica gel was added to suppress catalyst homo-dimerization, and the hydrogenated polymer was recovered as the di-ester-functionalized telechelic polyethylene with a molecular weight of 1.5 X 10 g moD fDP = 48) and a PDI of 1.9. 

End groups containing the silacyclobutane ring were successfully introduced as latent thermal cross-linkers, enabling the curing of the resulting homo-telechelic polymers at temperatures as high as 160-210 C into thermosets [101]. 

In an ideal ROMP/CT system, where chain termination reactions are absent, the number of functional end groups produced is determined only by the sum of the CTA and the initiator. Since the ratio of monomer to initiator concentration is typically kept very high, the total degree of functionalization is very close to the ideal value of 2. 

A supramolecular approach toward block copolymers was investigated by Higley et al. [128]. Using Wittig olefination, suitable long-chain olefinic esters 

All the above ROMP/CT approaches rely on reaching the thermodynamic equi-Ubrium in order to produce homo-telechelic polymers with high degrees of end-functionalization. A polydispersity index of ideally 2.0 is thus inevitable for this method. A different approach in which a kinetically controlled homo-telechelic 

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