Natural, reborn and eco-friendly polymers for biomedical and other bioapplications (NRE-BIOPOL)

X Carette, R Mincheva, M Herbin, X Noirfalise, T C Nguyen, P Leclere, T Godfroid, H Kerdjoudj, O Jolois, M Boudhifa Abstract In this study, a novel simple and fast method was developed of immobilizing a natural polysaccharide (chitosan) on a polylactide (PLA) surface. In order to overcome the lack of surface adhesion between the chitosan and the PLA due to incompatibility issues, atmospheric pressure plasma was used. The plasma activation was able to modify the PLA surface by generating surface chemistry proper for stabilizing the chitosan layer. The activation of the surface was monitored through water contact angle (WCA) measurements and X-ray photoelectron spectroscopy (XPS). Indeed, the introduction...

Angelica Avella, Rosica Mincheva, Jean-Marie RAquez, Giada Lo Re One-step reactive melt processing (REx) via radical reaction was evaluated with the aim of improving the rheological properties of poly(ε-caprolactone) (PCL). In particular, a water-assisted REx was designed under the hypothesis of increasing crosslinking efficiency with water as a low viscous medium in comparison with a slower PCL macroradicals diffusion in the melt state. To assess the effect of dry vs. water-assisted REx on PCL, its structural, thermo-mechanical and rheological properties were investigated. Water-assisted REx resulted in increased PCL gel fraction compared to dry REx (from 1 to 34 %), proving...

Julie Meimoun, Audrey Favrelle,-Huret, Marc Bria, Nicolas Merle, Grégory Stoclet, Julien De Winter, Rosica Mincheva, Jean-Marie Raquez, Philippe Zinck The epimerization of polylactide is reported in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at 105 °C in toluene. The extent of the reaction depends on the amount of TBD introduced and the reaction time. Up to ca. 46% D units can be formed starting from poly(l-lactide) in the presence of 5 mol% TBD. The epimerization rate is slightly higher for D-stereoisomers vs. L-stereoisomers. From the decrease of the number-average molecular weight observed, a concomitant chain scission reaction is observed. A possible mechanism...

M Ben Abdeljawad, X Carette, R Mincheva, J. Odent1 and J-M Raquez Abstract In this study, polylactide (PLA)/magnesium (Mg) composites were produced through extrusion and compression-molding. In order to enhance the interfacial adhesion between the hydrophobic matrix and the hydrophilic filler, an amphiphilic PEO-b-PLLA block copolymer was used. The morphological study shows an effective improvement of the PLA/Mg interactions following the copolymer addition. Moreover, the surface contact angle test proves the decrease of the PLA hydrophobicity. Thus, a significant influence on the cell adhesion is expected. Furthermore, hydroxyapatite formation in bulk after eight weeks of the immersion in a simulated body fluid (SBF) is also...

Florence Pilate, Zhi-Bin Wen, Farid Khelifa, Yan Hui, Sebastien Delpierre, Luo Dan, Rosica Mincheva, Philippe Dubois, Ke-ke Yang, Jean-Marie Raquez A novel poly(epsilon-caprolactone) (PCL) supramolecular network exhibiting shape-memory behavior was successfully constructed with pendant UPy units that are highly able to dimerize. The dynamic network was obtained by a simple and versatile strategy consisting of chain-extension reaction between α,ω-dihydroxyoligoPCL and hydroxylated UPy units in the presence of hexamethylene diisocyanate as a coupling agent and further intermolecular dimerization of the UPy along the polyurethane backbone. 1H NMR analyses confirmed the dynamic features of the system, and DMTA in tensile mode was investigated...

Valentina Sessini, Jean-Marie Raquez, Giada Lo Re, Rosica Mincheva, José Maria Kenny, Philippe Dubois, and Laura Peponi Abstract Smart multiresponsive bionanocomposites with both humidity- and thermally activated shape-memory effects, based on blends of ethylene-vinyl acetate (EVA) and thermoplastic starch (TPS) are designed. Thermo- and humidity-mechanical cyclic experiments are performed in order to demonstrate the humidity- as well as thermally activated shape memory properties of the starch-based materials. In particular, the induced-crystallization is used in order to thermally activate the EVA shape memory response. The shape memory results of both blends and their nanocomposites reflect the excellent ability to both humidity-...

A. Toncheva, R. Mincheva, M. Kancheva, N. Manolova, I. Rashkov, P. Dubois, N. Markova Antibacterial micro- and nanofibrous materials based on polylactide (PLA) and polyethylene glycol (PEG) were prepared by electrospinning. PEG incorporation was achieved by its physical blending with or chemical grafting on PLA. The role of the incorporation method on the surface wettability, the thermal, the mechanical and the biological properties was studied in relation to mats applicability. Physical blending or chemical grafting did not significantly modify the wettability of the mats, but showed a plasticizing effect on PLA – more obvious in the case of the physical blend fibers in agreement with...

Elena Yancheva, Dilyana Paneva, Nevena Manolova, Rosica Mincheva, Dobri Danchev, Philippe Dubois, and Illya Rashkov Poly(l-lactide) (PLLA) and poly(l-lactide)/poly(ethylene glycol) (PLLA/PEG) electrospun fibrous materials coated with a polyelectrolyte complex (PEC) were prepared. This was achieved by consecutive deposition of a layer of N-carboxyethylchitosan (CECh) and a layer of a double hydrophilic block copolymer, poly(ethylene oxide)-b-quaternized poly[2-(dimethylamino)ethyl methacrylate] (PEO-b-PDMAEMAQ100), resulting in PEC formation between the two polyelectrolytes on the surface. Noteworthy, to improve the water wettability of the electrospun PLLA fibrous materials, that is, to enable more uniform deposition of the polyelectrolyte partners, water/ethanol mixed solvent was used for preparation of CECh...

Rosica Mincheva, François Bougard, Dilyana Paneva, Magali Vachaudez, Nevena Manolova, Illya Rashkov, and Philippe Dubois For the first time, core−shell nanoparticles were prepared from the natural polyampholyte N-carboxyethylchitosan (CECh). This was triggered by polyelectrolyte complex (PEC) formation between CECh and strong polyelectrolyte-containing double hydrophilic block copolymers. Quaternized poly[2-(dimethylamino)ethyl methacrylate]-b-poly(ethylene oxide) (quaternized PDMAEMA-b-PEO) and sodium poly(2-acrylamido-2-methylpropane sulfonate)-b-poly(ethylene oxide) (PAMPSNa-b-PEO) were used as polycation and polyanion, respectively. Based on the proper choice of partners and medium conditions, spherical core−shell nanoparticles with PEO shell were obtained both in basic and in acidic medium. The size of the particles was in the range 230−450 nm...