No abstract

No abstract

No abstract

Aliphatic segmented poly(ester amide)s, comprising a crystallizable amide phase and a flexible amorphous ester phase, were investigated for potential use in biomedical applications. By varying the amide content and the type of crystallizable amide segments, the polymer's thermal and mechanical properties can readily be tuned. Polymers with 25 and 50 mol % of amide content are noncytotoxic and sustain growth of fibroblasts onto polymer films. The in vitro degradation of these polymers was followed in PBS (pH 7.4) at 37 degrees C up to 7 months. The poly(ester amide)s showed the characteristics of bulk degradation with a gradual decrease in molecular weight and almost no mass loss. The in vivo degradation of these polymers, followed by subcutaneous implantation in rats up to 6 weeks, was slow and similar to the in vitro degradation. The tissue response upon implantation was followed over 6 weeks. A mild foreign-body reaction, characterized by the presence of macrophages, and sporadically a lymphocyte, were observed in the first week of implantation. After 6 weeks the implant site is characterized by fibrous encapsulation with no signs of inflammation. The poly(ester amide)s tested are biocompatible, but their in vitro as well as in vivo degradation is very slow.

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.