Ring-opening polymerization block copolymer

Random and Block Copolymers by Ring-Opening Polymerization... 

Preparation and characteristics of ABA type polycaprolactone-b-polydimethyl-siloxane block copolymers have been recently reported 289). In this study, ring-opening polymerization of e-caprolactone was achieved in melt, using a hydroxybutyl terminated PSX as the initiator and a catalytic amount of stannous octoate. Reactions were completed in two steps as shown in Reaction Scheme XIX. 

This polymeric oxocarbenium salt readily initiates the cationic ring opening polymerization of oxolane to produce a polystyrene-polyTHF block copolymer. Molecular weight control is provided, polydispersity is narrow and compositional heterogeneity is small59). 

An alternate way to make block copolymers involving PDMS blocks 124,125) is to have these chains fitted with epoxide functions at chain end, and to react them with a vinylic or dienic polymer carrying terminal COOH functions. Sequential addition of monomers has also been used, the ring opening polymerization of the cyclic trimer (D3) being initiated by the anionic site of a living polymer126). 

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