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  • 1.
    Fagerland, Jenny
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. University of Sannio, Italy.
    Modulating the thermal properties of poly(hydroxybutyrate) by the copolymerization of rac-beta-butyrolactone with lactide2016In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 40, no 9, p. 7671-7679Article in journal (Refereed)
    Abstract [en]

    Biobased poly(hydroxybutyrate) is produced by microorganisms under controlled conditions. It is a linear, high molecular weight, fully isotactic and highly crystalline polymer. However, it has poor mechanical and thermal properties. We have modulated the thermal properties of this material by ring-opening co-polymerization of rac-beta-butyrolactone (BL) with lactide (LA) in the presence of salan-based yttrium and aluminum catalysts. The prepared poly(hydroxybutyrate-co-lactide) copolymers were characterized by proton and carbon nuclear magnetic resonance (H-1 and C-13 NMR), size exclusion chromatography (SEC) and differential scanning calorimetry (DSC) analyses. The salan-yttrium compound was a more effective catalyst compared to the aluminum compound, affording high molecular weight copolymers with higher monomer conversion and a monomodal distribution of the molecular weights. The kinetic experiments showed a higher rate of polymerization for the LA with respect to the BL. The copolymers were amorphous and DSC showed unique transition temperatures for all of the samples. The formation of a gradient copolymer is proposed.

  • 2.
    Fuoco, Tiziana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. University of Salerno, Italy.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. University of Sannio, Italy.
    A Route to Aliphatic Poly(ester)s with Thiol Pendant Groups: From Monomer Design to Editable Porous Scaffolds2016In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 4, p. 1383-1394Article in journal (Refereed)
    Abstract [en]

    Biodegradable aliphatic polyesters such as poly(lactide) and poly(ϵ-caprolactone), largely used in tissue engineering applications, lack suitable functional groups and biological cues to enable interactions with cells. Because of the ubiquity of thiol groups in the biological environment and the pliability of thiol chemistry, we aimed to design and synthesize poly(ester) chains bearing pendant thiol-protected groups. To achieve this, 3-methyl-6-(tritylthiomethyl)-1,4-dioxane-2,5-dione, a lactide-type monomer possessing a pendant thiol-protected group, was synthesized. This molecule, when used as a monomer in controlled ring-opening polymerization in combination with lactide and ϵ-caprolactone, appeared to be a convenient "building block" for the preparation of functionalized aliphatic copolyesters, which were easily modified further. A polymeric sample bearing pyridyl disulfide groups, able to bind a cysteine-containing peptide, was efficiently obtained from a two-step modification reaction. Porous scaffolds were then prepared by blending this latter copolymer sample with poly(l-lactide-co-ϵ-caprolactone) followed by salt leaching. A further disulfide exchange reaction performed in aqueous medium formed porous scaffolds with covalently linked arginine-glycine-aspartic acid sequences. The scaffolds were characterized by thermal and mechanical tests, and scanning electron microscopy surface images revealed a highly porous morphology. Moreover, a cytotoxicity test indicated good cell viability.

  • 3.
    Fuoco, Tiziana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Aluminum Alkyl Complexes Bearing Salicylaldiminato Ligands: Versatile Initiators in the Ring-Opening Polymerization of Cyclic Esters2017In: CATALYSTS, ISSN 2073-4344, Vol. 7, no 2, article id 64Article, review/survey (Refereed)
    Abstract [en]

    Linear aliphatic polyesters are degradable thermoplastic polymers, which can be obtained by ring-opening polymerization (ROP) of cyclic esters through a coordination-insertion mechanism. Aluminum based organometallic complexes have a leading position as efficient catalysts for this polymerization process. Aluminumalkyl complexes bearing salicylaldiminato ligands, although less explored, have been shown to be efficient and versatile catalysts for the ROP of various cyclic esters. These species have the potential to function as active catalysts in the ROP because of their less coordinatively saturated nature with respect to analogous SALEN-type complexes. They have been used as efficient catalysts in the ROP of commercially available cyclic esters, such as epsilon-caprolactone, L-lactide, rac-lactide, and glycolide. Moreover, they resulted in efficient catalysts for the ROP of cyclic esters with large ring-size and for the ROP of functionalized lactide. Furthermore, they have been used in the co- and ter-polymerization of various cyclic esters affording well controlled polymerization and a plethora of microstructural architectures, ranging from random to block to multiblock.

  • 4.
    Fuoco, Tiziana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Department of Science and Technology, University of Sannio, via dei Mulini 59/A, 82100 Benevento, Italy.
    Wistrand, Anna Finne
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Redox-Responsive Disulfide Cross-Linked PLA-PEG Nanoparticles2017In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 50, no 18, p. 7052-7061Article in journal (Refereed)
    Abstract [en]

    We have developed a strategy for the preparation of redox-responsive PEG PLA-based nanoparticles containing disulfide bonds that can be disassembled in the presence of cellular concentrations of glutathione. Functionalized poly-(lactide)s were prepared by ring-opening copolymerization of L-lactide and 3-methyl-6-(tritylthiomethyl)-1,4-dioxane-2,5-dione, a monomer bearing a pendant trityl-thiol group, followed by the postpolymerization modification of trityl-thiol into pyridyl disulfide groups. Polymeric networks composed of PLA and PEG blocks linked by disulfide bonds were prepared by a disulfide exchange reaction between the functionalized PLAs and telechelic PEG having thiol groups at both ends, HS-PEG-SH, in DMF. When dialyzed against water, they assembled into dispersible nanoparticles, with a flowerlike structure having a hydrophobic core and a hydrophilic shell, with sizes in the range 167-300 nm that are suitable for drug delivery. The effects of the number of functional groups, molecular weight, and concentration on the nanoparticle size were evaluated. The stability of the nanoparticles after dilution and the redox-responsive behavior in the presence of different concentrations of glutathione were assessed. The hydrophobic molecule Nile red could be encapsulated in the nanoparticles and then released in the presence of glutathione at cellular concentration.

  • 5. Gorrasi, Giuliana
    et al.
    Meduri, Angelo
    Rizzarelli, Paola
    Carroccio, Sabrina
    Curcuruto, Giusy
    Pellecchia, Claudio
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Univ Sannio.
    Preparation of poly(glycolide-co-lactide)s through a green process: Analysis of structural, thermal, and barrier properties2016In: REACTIVE & FUNCTIONAL POLYMERS, ISSN 1381-5148, Vol. 109, p. 70-78Article in journal (Refereed)
    Abstract [en]

    We have successfully synthesized poly(lactide), poly(glycolide), and poly(lactide-co-glycolide) copolymers in bulk by ring-opening homo- and copolymerization of glycolide and L-lactide, using sodium hydride as the environmentally friendly and nontoxic initiator. Random copolymers were obtained, and the microstructure was characterized by nuclear magnetic resonance (H-1 and C-13 NMR) and matrix-assisted laser desorption ionization mass spectrometry (MALDI MS). The mechanism of reaction was elucidated by analysis cif the polymer end groups. Homopolymer and copolymers films and their blends were obtained, and structure and physical properties analyzed. Thermal degradation analysis showed superior Characteristics of copolymers with respect to the blends. Transport properties of water vapor were also evaluated and correlated to the copolymer composition.

1 - 5 of 5
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