RESUMEN
One main application of resorbable poly-L-lactic acid (PLLA) and poly-L-lactic-co-glycolic acid (PLGA) based materials is in medical implants. In this study composites were made from PLLA and PLGA with hydroxyapatite (HAp) respective beta-tricalcium phosphate (beta-TCP) fillers. The filler content and particle size were varied, and the thermal properties as well as the mechanical strength of the composites were investigated. The composites were made by an extrusion compounding process giving 2-2.5 mm diameter sized profiles. The results verified that the thermal stability of the composites was reasonable during the optimized compounding conditions. Scanning electron microscopy revealed that the fillers were well dispersed in the polymer matrices. The mechanical properties were improved by the addition of the fillers. The optimum mechanical properties for the extruded profiles were obtained with the HAp fillers. The E-modulus was increased from 3.3 to 4.6 GPa by addition of filler particles (30 wt%) whereas the flexural strength was reduced from 133 to 106 MPa.
Asunto(s)
Cerámica , Ácido Láctico/química , Ácido Poliglicólico/química , Polímeros/química , Microscopía Electrónica de Rastreo , Poliésteres , Copolímero de Ácido Poliláctico-Ácido PoliglicólicoRESUMEN
The aim of this study was to synthesize on a larger scale, an experimental polyamide based on an amino acid of trans-4-hydroxy-L-proline. The polyamide of trans-4-hydroxy-L-proline has been used as porogen filler (i.e., a hydrophilic pore generating material) in nondegradable acrylic bone cement. In in vitro studies, this hydrophilic filling component has been shown to form porosity within the acrylic bone cement in an aqueous environment. The formation of in situ porosity in the acrylic polymer matrix is believed to improve the fixation between the cement and the living bone. Namely, a porous structure can support bone ingrowth and strengthen the mechanical connection between the acrylic bone cement and the bone. The monomer, trans-4-hydroxy-L-proline methyl ester, was prepared from trans-4-hydroxy-L-proline by means of two steps, and the monomer was then polymerized to polyamide of trans-4-hydroxy-L-proline. The polymerization was carried out using a melt polycondensation method. The molecular weights (M(psi)) of the produced polyamides were between 1800 and 3600. The products were characterized by FTIR and (1)H-NMR spectroscopy.
Asunto(s)
Hidroxiprolina/química , Nylons/análisis , Nylons/química , Polimetil Metacrilato/análisis , Polimetil Metacrilato/química , Ensayo de Materiales , Peso Molecular , PorosidadRESUMEN
The rigid linear ligands 1a-g and the macrocycle 2 undergo self-assembly via coordination with copper(I) ions to generate the series of rigid-rack inorganic pseudorotaxanes 3a-g. These complexes have been characterized by analytical and spectroscopic methods. Their architecture has been confirmed by determination of the crystal structures of 3e,f. The complex [Cu(2)(1e)(2)(2)](PF(6))(2) (3e) crystallizes in the space group C2/c, whereas complex [Cu(2)(1f)(2)(2)](PF(6))(2) (3f) gives crystals containing a single enantiomer in the chiral space group P2(1)2(1)2(1). The synthesis and solution structures of 3a-g and the solid-state structures of 3e,f are discussed in relation to the viability of multicomponent self-assembly as an approach to linear metal-ion arrays.