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A series of poly(ether ester)s containing different H-bonding units (amide, carbamate, urea) was prepared by polycondensation in bulk, using Ti(OBu)4 as a catalyst. The copolymers were obtained starting from PEG1000, 1,4-butanediol, and a symmetrical, bis-ester terminated monomer carrying H-bonding units. These materials were designed for biomedical applications, in which ultimate biodegradability of the materials is required. The influence of the nature of the H-bonding unit and of the length of the methylene spacer between H-bonding groups on the thermal and solubility properties of copolymers was investigated. Amide containing copolymers were more thermally stable than ones containing carbamate, consistent with the observed behavior of the corresponding monomers. In most cases, differential scanning calorimetry (DSC) traces were quite complex because of phase separation and dependent on the applied cooling rate. Copolymers containing urea bonds were less soluble in most organic solvents, but their thermal properties were not significantly different than their amide containing counterparts.

A wide range of poly(hydroxyalkanoate)s (PHAs), a class of biodegradable polyesters produced by various bacteria grown under unbalanced conditions, have been proposed for the fabrication of tissue-engineering scaffolds. In this study, the manufacture of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (or PHBHHx) scaffolds, by means of an additive manufacturing technique based on a computer-controlled wet-spinning system, was investigated. By optimizing the processing parameters, three-dimensional scaffolds with different internal architectures were fabricated, based on a layer-by-layer approach. The resulting scaffolds were characterized by scanning electron microscopy, which showed good control over the fibre alignment and a fully interconnected porous network, with porosity in the range 79-88%, fibre diameter 47-76 µm and pore size 123-789 µm. Moreover, the resulting fibres presented an internal porosity connected to the external fibre surface as a consequence of the phase-inversion process governing the solidification of the polymer solution. Scaffold compressive modulus and yield stress and strain could be varied in a certain range by changing the architectural parameters. Cell-culture experiments employing the MC3T3-E1 murine pre-osteoblast cell line showed good cell proliferation after 21 days of culture. The PHBHHx scaffolds demonstrated promising results in terms of cell differentiation towards an osteoblast phenotype. Copyright © 2014 John WileySons, Ltd.