Rotationsdispersion bei monomerem und polymerem L‐(–)‐Lactid

Abstract

ZUSAMMENFASSUNG:Bei der kationischen Polymerisation von L-Lactid entsteht ein hochkristallines, isotaktisches Polymeres. Physikalische Eigenschaften des Monomeren und Polymeren werden SUMMARY:In the cationic polymerization of L-lactide a high cristalline isotactic polymer is obtained. Physical properties of monomer and polymer are reported. The one-term DRUDE equation is valid for the optical rotatory dispersion of L-lactide in different solvents. The polymer shows a dispersion curve with a first extremum at 275 mp. The rotatory dispersion of the poly-L-lactide can be described by the MOFFITT-YANG equation. This permits conclusions on the secondary structure of the dissolved polymer.

Ring-opening polymerization of lactides using heterobimetallic yttrocene complexes

“…4) [13][14][15][16] . Likewise, the deviation of the optical rotations from the corresponding expected values 17,18) for random copolymerization is too small to suggest any preference of one of the enantiomers over the other (Fig. 8).…”

Biomacromolecules and Bio‐Related Macromolecules

“…Cationic polymerization of L,L-lactide was reported to produce crystalline isotactic PLA. [123] Trifluoromethanesulfonic acid and methyl triflate were useful initiators. [124] By using methyl triflate, the terminal group is a methyl ester moiety, indicating that the chain growth proceeds via cleavage of the alkyl-oxygen bond.…”

Optical rotatory properties and conformations of esters and polyesters of trans‐1,2‐cyclohexanedicarboxylic acid

“…Stereoregular polyesters investigated until now failed to show conformational order in solution. (23) The simplest optically active polyester, poly-(S)-lactic acid, has also been studied in solution, (24)(25)(26) and no positive evidence of secondary structure has been reported. It is more probable that the hyperchromic effect observed has to be ascribed to interactions between the two identical chromophores in the monomeric unit.…”