Tacticity biodegradable polymers

Figure 15 Ring-opening polymerization of cyclic esters to make biodegradable polymers (a) ROP of e-caprolactone (b) ROP of one enantiomer of lactide to give isotactic polymer and (c) ROP of rac-lactide to form polymers of variable tacticity...

In summary, the rate and the final state of biodegradation are strongly dependent on the tacticity in the case of homopolymers, or of the copolymer composition. This implies that it is possible to adjust the material s lifetime by controlling (/ )-units in the polymer or by changing the ratio of 3-HB to co-monomer units. 

The doublet structure of the methyl signal at 17 ppm is caused by the stereochemistry. Polylactides, not yet described in any pharmacopoeias, are rather new biodegradable polyesters derived from the chiral lactic acid and used, e. g., in drug delivery systems. The stereochemistry of the polymer is important to the physical and chemical behavior, especially the polymer properties. Pure tactic polymerization can be differentiated from atactic or mixed polymers by simple comparison of the C NMR spectra (Figure 3-10) [4]. 

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