Multiblock copolymers of lactic acid and ethylene glycol containing periodic side-chain carboxyl groups: synthesis, characterization, and nanoparticle preparation

D. D. Ankola, M.N.V. Ravi Kumar, F. Chiellini, R. Solaro

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Multiblock copolymers containing periodically spaced side-chain carboxyl groups were obtained by a two-step synthesis involving the preparation of ABA triblock prepolymers of lactic acid (A block) and ethylene glycol (B block) followed by chain extension to (ABA)n multiblock copolymers by reaction with pyromellitic dianhydride (PMDA). A series of polymer grades were synthesized by varying PEG and PLA chain length. NMR analysis demonstrated the incorporation of PMDA in polymer chain and revealed the possibility of PMDA units to exist in two isomers, cisoid and transoid forms. Chain extension resulted in the incorporation of free carboxylic groups in polymer backbone and in a 6-fold increase of molecular weight. Thermal analysis indicated that the extended polymers are more stable and have a Tg of 30−50 °C higher than their prepolymers. The polymers were found to be fast degrading in water following coupled first-order kinetics. Further, the carboxylated polymers can be processed into nanoparticulates by either nanoprecipitation or emulsion−diffusion methods resulting in 50−200 nm sized particles.
Original languageEnglish
Pages (from-to)7388-7395
Number of pages8
JournalMacromolecules
Volume42
Issue number19
DOIs
Publication statusPublished - 13 Oct 2009

Keywords

  • multiblock copolymers
  • lactic acid
  • ethylene glycol
  • synthesis
  • characterization
  • nanoparticle preparation
  • periodic side-chain carboxyl groups

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