Scientific article

Hydrolysis and Erosion Studies of Autocatalyzed Poly(ortho esters) Containing Lactoyl−Lactyl Acid Dimers

Published inMacromolecules, vol. 32, no. 2, p. 301-307
Publication date1999-01-05
First online date1999-01-05

Poly(ortho esters) based on 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,10-decanediol, and 1,10-decanediol dilactate were prepared and their hydrolysis in phosphate buffer at 37 °C and pH 7.4 was determined as a function of time. Specifically, kinetics of polymer weight loss, polymer molecular weight changes, release of lactic acid and release of propionic acid were determined. A significant decrease in molecular weight occurred within about 20 days. Weight loss and evolution of hydrolysis product occurred after an induction period that decreased with increasing content of the lactoyl−lactyl segment in the polymer. After the induction period, a concomitant rate of weight loss and release of hydrolysis products was noted. The rate increased with increasing content of the lactoyl−lactide segment. After a certain time period, size-exclusion chromatography revealed the formation of a peak at an apparent molecular mass of about 550 Da. The compounds under the peak were analyzed by electrospray ionization/mass spectrometry (ESI/MS) and found to consist of a multiplicity of lower molecular weight polymer hydrolysis fragments. On the basis of expected hydrolysis products, it was possible to assign a structure to most molecular weight peaks in the ESI/MS spectrum. The data were found to be consistent with a hydrolysis that takes place predominantly in the surface layers of the solid polymer.

Citation (ISO format)
SCHWACH, Khadija, HELLER, Jorge, GURNY, Robert. Hydrolysis and Erosion Studies of Autocatalyzed Poly(ortho esters) Containing Lactoyl−Lactyl Acid Dimers. In: Macromolecules, 1999, vol. 32, n° 2, p. 301–307. doi: 10.1021/ma981517m
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Article (Published version)
ISSN of the journal0024-9297

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