Poly(ester amide)s are an emerging group of biodegradable polymers that may cover both commodity and speciality applications. These polymers have ester and amide groups on their chemical structure which are of a degradable character and provide good thermal and mechanical properties. In this sense, the strong hydrogen-bonding interactions between amide groups may counter some typical weaknesses of aliphatic polyesters like for example poly(-caprolactone). Poly(ester amide)s can be prepared from different monomers and following different synthetic methodologies which lead to polymers with random, blocky and ordered microstructures. Properties like hydrophilic/hydrophobic ratio and biodegradability can easily be tuned. During the last decade a great effort has been made to get functionalized poly(ester amide)s by incorporation of -amino acids with hydroxyl, carboxyl and amine pendant groups and also by incorporation of carbon-carbon double bonds in both the polymer main chain and the side groups. Specific applications of these materials in the biomedical field are just being developed and are reviewed in this work (e.g., controlled drug delivery systems, hydrogels, tissue engineering and other uses like adhesives and smart materials) together with the main families of functionalized poly(ester amide)s that have been developed to date.
ABSTRACT:A new poly(ester amide) derived from L-alanine has been synthesized and characterized. The polymer has good fiber-and film-forming properties, as well as other characteristics like thermal stability and solubility in chloroform, which enhance its processing facilities. Degradation studies show that both pH and temperature influence in the hydrolisis rate that takes mainly place through the ester linkages. Degradation was also studied by using different enzymes. Results indicated that papain was the most efficient of these, and that the hydrolysis to water-soluble products could be attained in a few days. Basal cytotoxicity was assayed using a mouse L929 fibroblast permanent cell line. The MTT viability test was performed with liquid extract of the material (50 days, 37ЊC). An attachment and proliferation screening study with intact material was also carried out. No cytotoxic responses were detected, in either assay, after a 24-and 48-h incubation period with the cells. After 72 h a slight cytotoxicity was detected in the polymer material, while a more significant one was detected in the material extract.
A series of polyamides n,4 (n from 2 to 12) containing one methoxy group stereoregularly attached to each a carbon atom of the diacid repeating unit has been prepared by using L-tartaric acid as the starting material. Polycondensation in a solution of bis(pentachlorophenyl) 2,3-O-dimethyl-L-tartrate with the corresponding 1 ,n-alkanediamines afforded stereoregular polymers with molecular weights between 7 X 103 and 5 X 104 depending upon the value of n, in high yields. These polyamides were fully characterized by elemental analysis and IR and 1H/13C NMR spectroscopy. They are hydrophilic, melt above 185 °C, and display large optical activity. All these properties were investigated and found to correlate well with the * To whom correspondence should be addressed.
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