Heterostar copolymer

Similarly, star and heterostar copolymers, (97) and (98), have been reported to form from norbomene and 2,3-dicarbomethoxynorbornene or 5-cyanonor-bornene and 2,3-bis(trifluoromethyl)norbomadiene. 

If the two kinds of branches are of different chemical nature, but of similar length, the resulting heterostar copolymer molecule is composed of a crosslinked core carrying equal numbers of branches of two different kinds. A variety of branches can be attached to a primary PS star molecule. Branches of poly(ethylene oxide) [68,83], poly(alkyl methacrylate) [84], poly(ter -butyl acrylate) (PtBA) [82], poly(2-vinylpyridine) [85], and others have been developed, with special emphasis on amphiphilic heterostar molecules. The presence of a population of linear precursors remains however, they can be easily removed by fractional precipitation. Since polymers of different chemical nature are usually incompatible, there is a question of the conformation of such... 

The norbornadiene dimer exo-trans-exo-pentacyc ote-tradeca-5,11-diene has been employed as a crosslinking agent for the controlled synthesis of these star-shaped copolymers in the catalytic presence of W(CHr-Bu)(NAr)(0/-Bu)2 or Mo(CHr-Bu)(NAr)Or-Bu)2 [66], Star polymers in which the arms are block copolymers of different polarities can be prepared by this method, as well as star polymers in which the composition of the arms is different, as are the solubility characteristics and stereochemical regularity. Heterostars thus obtained, in which the number of the different arms will be approximately equal, may exhibit interesting intramolecular phase separations. 

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See also in sourсe #XX -- [ ]

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