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Solvent Casting (solvent + casting)
Selected AbstractsStem Cell Aligned Growth Induced by CeO2 Nanoparticles in PLGA Scaffolds with Improved Bioactivity for Regenerative MedicineADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Corrado Mandoli Abstract Hybrid 2D polymeric,ceramic biosupports are fabricated by mixing a nanostructured CeO2 powder with 85:15 poly(D,L -lactic- co -glycolic acid) (PLGA)/dichloromethane solutions at specific concentrations, followed by solvent casting onto pre-patterned molds. The mold patterning allows the orientation of ceramic nanoparticles into parallel lines within the composite scaffold. The ability of the produced films to host and address cell growth is evaluated after 1, 3, and 6 days of culturing with murine derived cardiac and mesenchymal stem cells (CSCs and MSCs), and compared with PLGA films without ceramics and loaded with nanostructured TiO2. Aligned cell growth is observed only for scaffolds that incorporate oriented ceramic nanoparticles, attributed to the nanoceramic ability to modulate the roughness pitch, thus improving cell sensitivity towards the host surface features. Better CSC and MSC proliferative activity is observed for CeO2 composites with respect to either TiO2 -added or unfilled PLGA films. This evidence may be related to the nanostructured CeO2 antioxidative properties. [source] Benzoxazine containing polyester thermosets with improved adhesion and flexibilityJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2010Alev Tuzun Abstract High molecular weight polyesters containing thermally curable benzoxazine units in the main chain have been synthesized. For this purpose, first the diol functional monomer is synthesized through the Mannich and subsequent ring closure reactions of bisphenol-A, paraformaldehyde, and 5-amino-1-pentanol. Polycondensation of the resulting benzoxazine and pyromellitic dianhydride or 4-4,-(hexafluoroisopropylidene) diphatalic anhydride with or without dibutyltin laurate yielded the corresponding polyesters with the molecular weights between 5800 and 7000 Da. The structures of the precursor diol monomer and the resulting polyesters are confirmed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy analysis. Curing behavior of both the monomer and polymers has also been studied by differential scanning calorimetry. Flexible films of the polyesters were obtained by solvent casting on tin plates and crosslinked by heating in the absence of any catalyst. The cured films exhibited high flexibility and adhesion on the tin plates as determined by ASTM and DIN tests. Thermal properties of the cured polymers were also investigated by thermogravimetric analysis (TGA). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4279,4284, 2010 [source] Sulfonated poly(ether sulfone)s with binaphthyl units as proton exchange membranes for fuel cell applicationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2009Kazuya Matsumoto Abstract Sulfonated poly(ether sulfone)s containing binaphthyl units (BNSHs) were successfully prepared for fuel cell application. BNSHs, which have very simple structures, were easily synthesized by postsulfonation of poly(1,1,-dinaphthyl ether phenyl sulfone)s and gave tough, flexible, and transparent membranes by solvent casting. The BNSH membranes showed low water uptake compared to a typical sulfonated poly(ether ether sulfone) (BPSH-40) membrane with a similar ion exchange capacity (IEC) value and water insolubility, even with a high IEC values of 3.19 mequiv/g because of their rigid and bulky structures. The BNSH-100 membrane (IEC = 3.19 mequiv/g) exhibited excellent proton conductivity, which was comparable to or even higher than that of Nafion 117, over a range of 30,95% relative humidity (RH). The excellent proton conductivity, especially under low RH conditions, suggests that the BNSH-100 membrane has excellent proton paths because of its high IEC value, and water insolubility due to the high hydrophobicity of the binaphthyl structure. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5827,5834, 2009 [source] Poly(arylene sulfide)s by nucleophilic aromatic substitution polymerization of 2,7-difluorothianthreneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2009Maxwell J. Robb Abstract Poly(thianthrene phenylene sulfide) and poly(thianthrene sulfide) have been prepared by nucleophilic aromatic substitution polymerization of the activated monomer 2,7-difluorothianthrene with bis thiophenoxide and sulfide nucleophiles, respectively. The resulting polymers are thermally stable, amorphous materials that have been characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry, UV-Vis spectroscopy, refractometry, and intrinsic viscosity (IV) measurements. The polymers produced exhibit 5% weight loss values approaching 500 °C in inert and air atmospheres and glass transition temperatures that range from 149 to 210 °C. Poly(thianthrene phenylene sulfide) with a number average molecular weight of 22,100 g/mol has been synthesized with an IV in DMPU of 0.62 dL/g at 30 °C. Creasable films of this polymer have been prepared by solvent casting and melt pressing at 250 °C. Films of poly(thianthrene phenylene sulfide) exhibit transparencies greater than 50% at wavelengths exceeding 400 nm and a high refractive index value of 1.692 at a wavelength of 633 nm, making the polymer interesting for optical applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2453,2461, 2009 [source] Electrical and mechanical properties of multi-walled carbon nanotubes reinforced PMMA and PS compositesPOLYMER COMPOSITES, Issue 7 2008R.B. Mathur The use of multi-walled carbon nanotubes (MWCNT) as reinforcing material for thermoplastic polymer matrices, polymethyl methacrylate (PMMA), and polystyrene (PS) has been studied. MWCNT were synthesized by chemical vapor deposition (CVD) technique using ferrocene-toluene mixture. As-prepared nanotubes were ultrasonically dispersed in toluene and subsequently dispersed in PMMA and PS. Thin polymer composite films were fabricated by solvent casting. The effect of nanotube content on the electrical and mechanical properties of the nanocomposites was investigated. An improvement in electrical conductivity from insulating to conducting with increasing MWCNT content was observed. The carbon nanotube network showed a classical percolating network behavior with a low percolation threshold. Electromagnetic interference (EMI) shielding effectiveness value of about 18 dB was obtained in the frequency range 8.0,12 GHz (X-band), for a 10 vol% CNT loading. An improved composite fabrication process using casting followed by compression molding and use of functionalized MWCNT resulted in increased composites strength. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] | ||||||||||