Stereochemistry of poly epoxides

Poly(epoxides) are readily prepared by a ring-opening addition polymerisation catalysed by anionic, cationic or coordination catalysts. Consider the polymerisation of an epoxide bearing a single substituent  

This chain contains a truly chiral centre and a chain with only a single configuration would be optically active. As far as NMR is concerned, it is the relative configuration that is important, and as for vinyl polymers, the stereochemical sequence structure may be described in terms of m (same configuration) and r (opposite configuration) dyad building blocks repre- 

Unlike a vinyl monomer, the epoxide monomer is itself chiral. If the polymerisation proceeds by ring-opening at the CH2-O bond, the chirality is 

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