Synthesis and properties of block poly(ether-ester)s based on poly(ethylene oxide) and various hydrophobic segments

To obtain biodegradable amphiphilic block polymers for biomedical applications, a series of poly(ether-ester)s based on poly(ethylene oxide) and various hydrophobic/hydrophilic segment ratios were synthesized by the solution polymerization technique. The polyesters were characterized using (1)H NMR spectroscopy, elemental analysis, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis and compression stress-strain measurements. The composition of the poly(ether-ester)s agreed with the feed ratio. A study of the degree of phase segregation in the polymers evidenced that microphase mixing increases with the presence in the hydrophobic segments of polar groups able to establish interactions with the poly(ethylene oxide). This phase mixing increased the thermal stability of the acidic poly(ether-ester)s. Nanospheres for drug delivery with an average diameter of 50 nm were obtained by employing the acidic poly(ether-ester) showing less microphase segregation, while a scaffold structure with a homogeneous and highly interconnected porosity and an average pore size of approximately 15 mu m for tissue engineering was prepared using the more hydrophobic copolymer not possessing functional groups. Compression mechanical measurements carried out on the scaffold showed that the more hydrophobic copolymer was suitable for tissue engineering applications. In order to obtain polymers employable both in drug delivery and in tissue engineering a series of block poly(ether-ester)s showing various phase segregations were synthesized by varying the hydrophobic/hydrophilic segment ratio. (C) 2010 Society of Chemical Industry