A Review Of New Trends In Lactide Polymerisation Based On Metal Complexes

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An assessment of biopolymer- and synthetic polymer-based scaffolds for bone and vascular tissue engineering

The promise of tissue engineering is the combination of a scaffold with cells to initiate the regeneration of tissues or organs. Engineering of scaffolds is critical for success and tailoring of polymer properties is essential for their good performance. Many different materials of natural and synthetic origins have been investigated, but the challenge is to find those that have the right mix of mechanical performance, biodegradability and biocompatibility for biological applications. This article reviews key polymeric properties for bone and vascular scaffold eligibility with focus on biopolymers, synthetic polymers and their blends. The limitations of these polymeric systems and ways and means to improve scaffold performance specifically for bone and vascular tissue engineering are discussed. © 2013 Society of Chemical Industry

Diblock poly(ester)-poly(ester-ether) copolymers: I. Synthesis, thermal properties, and degradation kinetics

The synthesis and characterization of polycaprolactone (PCL) and poly(dioxanone-methyl dioxanone) (P(DX-co-MeDX)) block copolymers in a range of compositions of the two segments and with varying methyl dioxanone units is herein reported. The thermal properties of the copolymers were studied by differential scanning calorimetry (DSC) which revealed that copolymers exhibited two melting transitions ranging between 48 and 53 °C for the PCL segment and 71-79 °C for the P(DX-co-MeDX) segment. Copolymers exhibited only one crystallization exotherm which decreased as the MeDX content of the copolymer increased, thereby increasing miscibility of PCL and P(DX-co-MeDX) segments, a result also confirmed by scanning electron micrographs (SEM). Lastly, the kinetics of thermal degradation of PCL-b-P(DX-co-MeDX) copolymers were investigated by thermogravimetric analysis (TGA). Thermal degradation was shown to proceed in three distinct steps with the P(DX-co-MeDX) segment degrading in the first stage followed by the PCL segment in the last two stages most likely via unzipping and random polymerization mechanisms. The activation energies of copolymer degradation were determined and were found to decrease with increasing MeDX content of the copolymer. Overall, increasing MeDX content influenced both thermal properties and degradation kinetics through phase mixing of segments in the copolymers. © 2012 American Chemical Society

Characterization of electrospun novel poly(ester-ether) copolymers: 1,4-Dioxan-2-one and D,L-3-Methyl-1,4- dioxan-2-one

Introduction: Because tissue engineering scaffolds serve as a temporary environment until new tissue can be formed, their mechanical performance, thermal properties, and biocompatibility are critical for maintaining their functionality. The goal of this study was to electrospin scaffolds from copolymers containing varying amounts of 1,4-Dioxan-2-one (DX) and D,L-3-Methyl-1,4-dioxan-2-one (DL-3- MeDX), and characterize their mechanical and thermal properties. Methods and Results: Image tool analysis of scanning electron micrographs revealed the presence of DL-3-MeDX causes the fiber diameter of the scaffold to decrease as compared to polydioxanone (PDO). Uniaxial tensile testing revealed increasing amounts of DL-3-MeDX in the copolymer decreases scaffold peak stress, strain at break and toughness. Modulated differential scanning calorimetry was used for thermal analysis of the scaffolds and showed that increasing amounts of DL-3-MeDX causes a decrease in the melting as well as crystallization temperatures. Conclusion: Based on the results of the mechanical and thermal properties of these copolymer scaffolds, it is evident that these constructs could be functional in a variety of biomedical engineering applications

Poly(ester-ether)s: I. investigation of the properties of blend films of polydioxanone and poly(methyl dioxanone)

This study aimed at examining the properties of blends of semi-crystalline polydioxanone (PDX) and amorphous poly(methyl dioxanone) (PMeDX). The authors show that low amounts of PMeDX, within 15 wt% acts as plasticizer to high molar mass PDX as confirmed by an increase in Young\u27s modulus of films. The plasticizing effect on blends increased with decreasing reduced viscosity of PMeDX. Mechanical tests showed overall reduced tensile properties of the blends. Viscosity analysis coupled with SEM and AFM indicated immiscibility of the blends over the whole range of compositions. Blend samples with higher PMeDX contents degraded at faster rates with profiles differing from PDX. © 2014 Copyright Taylor & Francis Group, LLC