Block copolymers by sequential addition of monomers to living systems

4 Block copolymers by sequential addition of monomers to living systems 

Early attempts at making block copolymers using first-generation catalysts met with limited success. Thus, when cyclooctatetraene (M2) is added to a freshly polymerized solution of cyclooctene (MO, made with a W-based catalyst, the UV spectrum of the product indicates that at least two or three molecules of M2 have added to the chains (Korshak 1985). 

System Monomer M2 Catalyst Reference System Monomer M2 Catalyst Reference  

Tg of each block and the isotropization temperature of the mesophase are independent of the composition of the block copolymer and the same as those of the respective homopolymers. 5-Cyanonorbom-2-ene and methyltetracyclododecene have also been used as M]. 

Amphiphilic star-block copolymers can be readily prepared by the use of a suitable polycyclic diene such as 4 or the more readily available 5. For example, monomer 6 is first added to the initiator Mo-2 (Table 14.1), followed by norbomene 

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B. Block Copolymers by Sequential Addition of Monomers to Living Systems... 

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