Hydrolysis of lactic acid based poly(ester-urethane)s

✍ Scribed by Hiltunen, Kari; Tuominen, Jukka; Seppälä, Jukka V.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 237 KB
• Volume: 47
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(1998100)47:2<186::aid-pi47>3.0.co;2-e

✦ Synopsis

The hydrolysis behaviour of lactic acid based poly(ester-urethane)s has been studied in a bu †er solution of pH 7É00 at 37 and 55¡C. Samples were prepared using a straight two step lactic acid polymerization process. The lactic acid was Ðrst polymerized by condensation with a low molecular weight by hydroxyl terminated telechelic prepolymer and the molecular weight then was increased with a chain extender such as a diisocyanate. In the hydrolysis study, the e †ect on the hydrolysis rate of di †erent stereostructures (di †erent amount of D-units in the polymer chain) and the length of the ester units were studied. The rate of hydrolysis was examined by various techniques including weighing (water absorption and weight loss), GPC (molecular weight and polydispersity), and DSC (thermal properties). GPC measurements showed that at 37¡C the weight average molecular weight of the poly(ester-urethane)s started to decrease slowly during the Ðrst week of hydrolysis, but that at 55¡C the weight average molecular weight decreased dramatically during the Ðrst week of hydrolysis. SigniÐcant mass loss occurred later at both temperatures.