A Straightforward Synthesis of Well-Defined Difluorophosphonylated Terminated Poly(epsilon-caprolactone) for Grafting onto Iron Oxide Magnetic Nanoparticles
Résumé
Novel α-difluoromethylenephosphonate, ω-hydroxyl-terminated poly(ε-caprolactone)s (pCF2-PCL-OH) were successfully prepared for the first time by ring-opening polymerization of ε-caprolactone in the presence of diisopropyl (1,1-difluoro-5-hydroxypentyl)phosphonate (pCF2OH) as the initiator and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the catalyst. The so-obtained pCF2-PCL-OHs were thoroughly characterized by 1H NMR, 13C NMR, 31P NMR spectroscopies, SEC, and MALDI-TOF mass spectrometry. Dealkylation of the phosphonate ester-functionalized polymers was performed using trimethylsilyl bromide to afford the corresponding difluorophosphonic acid-terminated PCL analogues. They were used for coating magnetite nanoparticles to afford composite iron oxide nanoparticles with a mean diameter <20 nm as measured by TEM.