Polystereoisomers of 2-butyl and 3,3-dimethyl-2-butyl malic acid esters: configurational structures/properties relationship

New poly(P-malic acid alkyl esters) with two stereogenic centers have been synthesized by anionic ring-opening polymerization of racemic and optically active 2-butyl and 3,3-dimethyl-2-butyl malolactonates. The configurationa l structure of these racemic and optically active polyesters has been deter mined by C-13 NMR analysis. Comparison between polydiastereisomers structur es has been possible by using this spectroscopic method. Several main-chain and side-chain carbon atoms were stereosensitive, and polystereoisomers co mposition has been deduced from C-13 NMR spectra. Thermal properties of the different polystereoisomers have been correlated with the configuration of both chiral sites in the macromolecular chains. It has been shown, crystal linity rate was dependent on main-chain configurational structure. The late ral stereogenic center is important to increase the organization of macromo lecular chains in crystallites and therefore their regularity. Moreover, th e presence of the 3,3-dimethyl-2-butyl group led to a semi-crystalline race mic polymer, that confirms the particular behaviour of this bulky group in a macromolecular architecture. Comparison has been done with poly(benzyl 3- alkylmalates) containing two stereogenic centers in the main-chain. (C) 200 0 Elsevier Science Ltd. All rights reserved.