POSS end-linked peptide-functionalized poly(-caprolactone)s and their inclusion complexes with [alpha]-cyclodextrin

• Published in: Journal of polymer science. Part A, Polymer chemistry Polymer chemistry, 2016-11, Vol.54 (22), p.3643
• Main Authors: Haldar, Ujjal, Saha, Biswajit, Azmeera, Venkanna, De, Priyadarsi
• Format: Article
• Language: English
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/pola.28254

In this report, we have synthesized organic/inorganic hybrid peptide-poly(-caprolactone) (PCL) conjugates via ring opening polymerization (ROP) of -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 1H and 29Si 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 1H 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. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3643-3651.