Poly(ester-ether-ester) block copolymers, belonging to a class of biodegradable materials, were synthesized from poly(ethylene glycol) and epsilon-caprolactone by a simple ring-opening mechanism, which avoids the use of potentially toxic inorganic or organometallic initiators. The morphological and mechanical properties of such materials were investigated by gel-permeation chromatography, vapour pressure osmometry, proton magnetic resonance, infrared spectroscopy, differential scanning calorimetry, X-ray diffractometry and stress-strain tensile tests. The biocompatibility was investigated by cytotoxicity and hemocompatibility tests; the cytotoxicity was tested by the Neutral Red uptake assay, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, the Kenacid Blue R-binding method, and by the cell proliferation test on polymer films; the hemocompatibility was tested by the contact activation both of the coagulation cascade (intrinsic pathway), by the plasma prekallikrein activation test, and of the thrombocytes, by measuring the release of platelet factor 4 and beta-thromboglobulin. The experimental results show that such a polymerization process permits high-molecular mass block copolymers with relatively good tensile and mechanical properties to be obtained. Their cyto- and hemo-compatibility makes them suitable for employment as biomaterials

No abstract

Degradable segmented poly(ether‐ester‐urethanes) of variable segment chemistry and content were synthesized and characterized. Polycaprolactone diol, a series of poly(ether‐ester) block copolymers, and a diisocyanate giving non toxic degradation products were used to form the prepolymer. Cyclohexane dimethanol and a L–phenylalanine–based diester (Phe diester) were used as chain extenders. The influence of α‐chimotrypsin on the degradation was investigated by exposing the polymers to buffer and enzyme solutions for 12 days. The SEM, SEC, and gravimetric results showed that a significant erosion of the Phe diester containing polymer compared with the control polyurethane occurred in the presence of the enzyme but not in a normal buffer solution.

The radical polymerization of acrylic acid and sodium 4-styrenesulfonate in the presence of chitosan as a template gives insoluble products, identified as the polyelectrolyte complexes chitosan-poly(acrylic acid) and chitosan-poly(4-styrenesulfonate). Kinetic results do not permit to propose any mechanism in the first case, while suggest a ''pickup'' one in the second. The polyelectrolyte complexes have been characterized by FT-IR spectroscopy, X-ray diffractometry, optical and scanning electron microscopies, differential scanning calorimetry and thermogravimetric analysis. The results obtained indicate an ordered structure for the first complex, while the second one appears similar to that obtained by reacting the parent polymers. Therefore, the template polymerization technique appears advantageous only for the synthesis of the chitosan-poly(acrylic acid) complex. The thermal analysis shows that the complexes undergo two successive modifications on heating. FT-IR analysis demonstrates that the first process is an esterification between the hydroxyls of chitosan and the acidic groups of both daughter polymers; the second one appears to be an amidation of the chitosan ammonium groups only with the sulfonate groups

Composite materials were prepared by mixing in different proportions of hydroxyapatite (HA) and poly(epsilon-caprolactone-oxyethylene-epsilon-caprolactone) block copolymer (PCL-POE-PCL) to produce a new resorbable material for biomedical applications. This material has proved to be very interesting for production of periodontal membranes. Mechanical properties are linearly proportional to the amount of HA introduced. Fourier transform infrared (FTIR) investigations have pointed out that HA is able to influence some close epsilon-caprolactone molecules to start its homopolymerization giving PCL with an end chain ionic bonding. HA grains are therefore surrounded by a film of PCL which grants close connection of HA grains within copolymeric matrix. This interface bond with PCL is, however, an interesting occurrence for preparations of HA/PCL composites.