Special reactions for preparation of block copolymers

A special case is the use of the Witting reaction. Poly(p-phenylene pentadienylene)  

Subsequently, the terminal aldehyde groups are reduced with NaBH4 and the silyl groups cleaved off by treatment with tetrabutylanmionium fluoride to produce a hydrophobic-hydrophilic A-B diblock copolymer. 

Polyamide-polyether block copolymers can be formed by a variety of techniques. One of them consists of initial preparation of amine-terminated polyethers. This can be done by reacting hydroxv-terminated polyethers with acrylonitrile and then reducing the nitrile groups to amines  

The products of the reduction condense with carboxylic acid-terminated polyamides to form block copolymers. 

Another technique is to form the polyethers with terminal chloride groups. Hydroxy-group-terminated polyethers, for instance, can be converted to halogen-terminated polyethers. The products will react with ammonia and the amine-terminated polymer will react with carboxylic acid-terminated polyamides.  

A special case is the use of the Witting reaction. Poly(p-phenylene pentadienylene) [415] is prepared by this reaction first. This is utilized in a preparation of a block copolymer [456] according to the 

Living metathesis type polymerization was also employed to form block copolymers from norbornene and its derivative with bimetallic ruthenium catalysts, (PR3)2Cl2Ru(=CH-p-C6H4CH=) RuCl2(PR3)2 [434], This can be illustrated as follows [434]  

Pitet and HiUmyer [436] formed triblock copolymers from 1,5-cycloocatadiene and OL-Lactide by combining ring opening metathesis polymerization with cyclic ester ring opening polymerization. 

Proto et al. [434] living isoselective coordination polymerization of styrene to form isoselective block copolymers. This was accomplished by sequential monomer addition. 

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