Well-Defined Poly(lactic acid)s Containing Poly(ethylene glycol) Side Chains
journal contributionposted on 10.01.2012, 00:00 by José A. Castillo, Dorothee E. Borchmann, Amy Y. Cheng, Yufeng Wang, Chunhua Hu, Andrés J. García, Marcus Weck
Poly(ethylene glycol) (PEG) side-chain functionalized lactide analogues have been synthesized in four steps from commercially available l-lactide. The key step in the synthesis is the 1,3-dipolar cycloaddition between PEG-azides and a highly strained spirolactide–heptene monomer, which proceeds in high conversions. The PEG-grafted lactide analogues were polymerized via ring-opening polymerization using triazabicyclodecene as organocatalyst to give well-defined tri- and hepta(ethylene glycol)–poly(lactide)s (PLA) with molecular weights above 10 kDa and polydispersity indices between 1.6 and 2.1. PEG–poly(lactide) (PLA) with PEG chain Mn 2000 was also prepared, but GPC analysis showed a bimodal profile indicating the presence of starting macromonomer. Cell adhesion assays were performed using MC3T3-E1 osteoblast-like cells demonstrating that PEG-containing PLA reduces cell adhesion significantly when compared to unfunctionalized PLA.