Journal of Polymer Science Part A: Polymer Chemistry, Vol.54, No.22, 3643-3651, 2016
POSS End-Linked Peptide-Functionalized Poly(epsilon-caprolactone)s and Their Inclusion Complexes with alpha-Cyclodextrin
In this report, we have synthesized organic/inorganic hybrid peptide-poly(epsilon-caprolactone) (PCL) conjugates via ring opening polymerization (ROP) of epsilon-caprolactone (CL) in the presence of two sequence defined peptide initiators, namely POSS-Leu-Aib-Leu-NH2 (POSS: polyhedral oligomeric silsesquioxane; Leu: Leucine; Aib: alpha-aminoisobutyric acid) and OMe-Leu-Aib-Leu-NH2. Covalent attachment of peptide segments with the PCLs were examined by H-1 and Si-29 NMR spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and FTIR spectroscopy. Supramolecular inclusion complexations of synthesized peptide-PCL conjugates with alpha-cyclodextrin (alpha-CyD) were studied to understand the effect of POSS/OMe-peptide moieties at the PCL chain ends. Inclusion complexation of peptide-PCL conjugates with alpha-CyD produced linear polypseudorotaxane, confirmed by H-1 NMR, FTIR, powder X-ray diffraction (PXRD), polarized optical microscopy (POM) and differential scanning calorimetry (DSC). Extent of alpha-CyD threading onto the hybrid peptide-PCL conjugated polymers is less than that of alpha-CyD threaded onto the linear PCL. Thus, PCL chains were not fully covered by the host alpha-CyD molecules due to the bulky POSS/ OMe-peptide moieties connected with the one edge of the PCL chains. PXRD experiment reveals channel like structures by the synthesized inclusion complexes (ICs). Spherulitic morphologies of POSS/OMe-peptide-PCL conjugates were fully destroyed after inclusion complexation with alpha-CyD and tiny nanoobjects were produced. (C) 2016 Wiley Periodicals, Inc.
Keywords:host-guest inclusion complex;host-guest systems;peptides;polycaprolactone;polypseudorotaxane;ring-opening polymerization