Epoxide polymers stereochemistry

Vandenberg, E.J., 1969. Epoxide polymers synthesis stereochemistry structure and mechanism. J. Polym. Sci. Part A Polym. Chem. 7 (2), 525-567. 

Vandenberg, E. J. Epoxide polymers Synthesis, stereochemistry, structure, and mechanism. J. Poly. Sci., Poly. Chem. Ed. 1969, 7, 525-567. 

The final part of this book features tactic polymerizations of functional and nonolefinic (ring-opening) monomers— materials for which many aspects of polymer stereochemistry and microstructure control are very different than for simple polyolefins. Acrylate, epoxide, and lactide polymerizations are addressed in this part, along with tactic olefin/carbon monoxide co- and terpoly-mers. These final chapters provide an expanded view of polymer microstructures and stereocontrol strategies, such as enantiomer-selective polymerization, that may be less familiar to the polyolefin-minded chemist and serve to enhance the reader s overall understanding of stereoregular polymers and polymerization. 

The stereochemistry of ring-opening polymerizations has been studied for epoxides, episul-fides, lactones, cycloalkenes (Sec. 8-6a), and other cyclic monomers [Pasquon et al., 1989 Tsuruta and Kawakami, 1989]. Epoxides have been studied more than any other type of monomer. A chiral cyclic monomer such as propylene oxide is capable of yielding stereoregular polymers. Polymerization of either of the two pure enantiomers yields the isotactic polymer when the reaction proceeds in a regioselective manner with bond cleavage at bond 1. 

Through the controlled degradation of the polyethers to diol dimers using -butyl lithium, the stereochemistry of the monomer units in the polymer chain was determined. The decomposition of all four polymers showed that inversion of stereochemistry at the site of attack on the epoxide ring occurred in both polymerization mechanisms. The cis epoxides (RS stereocenters) produce monomeric units in the polymer chain with RR and SS stereocenters, and the trans epoxides (either... 

---