Poly ester amide

Lin et al. [206] blended PLA with HBP and observed that adding a small amount of HBP (2.5%) resulted in a significant decrease in the complex viscosity of PLA. This has been ascribed to a decrease in the entanglement and increase in the free volume of the blends. Crystallization of the blends increased compared to neat PLA. PLA, HBP/PLA (2.5/ 97.5), and HBP/PLA (10/90) had 20%, 31%, and 34.9% crystallinity, respectively. The blends demonstrated significant improvement in elongation at break compared to neat PLA. 

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The absorption rate has been examined in vivo for a series of poly(ester—amides) having the following formula ... 

The metabohc rate of poly(ester—amide) where x = Q has been studied in rats using carbon-14 labeled polymer. This study indicates that polymer degradation occurs as a result of hydrolysis of the ester linkages whereas the amide linkages remain relatively stable in vivo. Most of the radioactivity is excreted by urine in the form of unchanged amidediol monomer, the polymer hydrolysis product (51). 

TH Barrows. Bioabsorbable poly(ester-amides). In SW Shalaby, ed. Biomedical Polymers Designed-to-Degrade Systems. Cincinnati, OH Hanser/Gardner, 1994, pp 97-116. 

Copolymers of a-hydroxy acids and a-amino acids are one type of poly(ester-amide)s and are called polydepsipeptides (PDPs) [17]. Since some of natural occurring a-amino acids, typically Asp, Glu, lysine (Lys), cysteine (Cys), serine (Ser), and threonine (Thr), possess reactive (hydrophilic) side-chain groups, PDPs... 

Polyesterl-Woc -polyester2, 7 646 Poly(ester amides), bioresorbable polymers, 3 739-740... 

Commercially available hyperbranched polymer, a poly(ester-amide) is currently being marketed by DSM under the product name Hybrane [13] (Figure 8.2). It is also a hydroxyl-functionalized product, but contains both amide and ester linkages. The synthesis is accomplished in two steps cyclic anhydrides are reacted with diisopropanolamine to give an amide-intermediate, possessing two hydroxyl groups and one carboxylic acid. The subsequent polymerization takes places via an oxazolinium intermediate which results in the formation of a... 

Figure 8.2 A schematic representation of hydroxy-functional hyperbranched poly(ester-amide) Hybrane based on diisopropanolamine and an anhydride [11]...

Kricheldorf et al. have investigated several hyperbranched poly(ester-amide)s derived from combinations of 3,5-diaminobenzoic acids and 3,5-dihydroxy-benzoic acids and similar monomers [100-102]. The polymers exhibited values of Tg ranging from 160 to 250 °C and were highly soluble in various solvents. They employed diamines as star centers in order to control the molecular weight. 

Note 1 The rigid backbone often has a polyester, polyamide or poly(ester-amide) type of structure. Examples are ... 

Feng Y, Klee D, Keul H, Hdcker H (2000) Lipase-catalyzed ring-opening polymerization of morpholine-2,5-dione derivatives a novel route to the synthesis of poly(ester amide)s. Macromol Chem Phys 201 2670-2675... 

Polyesters [2] find use in fibers [poly(ethylene terephthalate), poly(ethylene oxybenzoate), poly(ester ethers), poly(ester amides), etc.] [1], coatings (especially unsaturated polyesters) [4], plasticizers, adhesives, polyurethane base resins, films, etc. Cross-linked polyesters prepared from glycerol and phthalic anhydride (alkyd resins) have been reviewed [20], High-melting poly aryl esters have been investigated for high-temperature applications. 

Poly (ester-amide) elastomers were prepared by Pacetti et al. (1) and used with implantable medical devices. 

Biocompatible materials consisting of poly(ester-amides), (I), were prepared by DesNoyer et al. (2) and used in cardiovascular medical devices. 

Katsarava et al. (4) prepared biodegradable hydrogels, (III), consisting of epoxy-containing poly(ester amides), which were used as implantable medical devices for delivery of biologically active agents. 

Title Epoxy-Containing Poly(ester amides) and Method of Use... 

Research Focus Synthesis of biocompatible poly(ester-amides) containing linear a-amino... 

Observations Condensation polymerization was used to prepare poly(ester-amides)... 

Biocompatible aromatic poly(ester-amide), (1 ), were prepared by Gomurashvili et al. (3) and used as stents in internal fixation devices. 

Semicrystalline implantable poly(ester-amide) derivatives, (II), containing phenylalanine were prepared by Trollsas et aL (3) and used medical devices. 

Several poly(urea urethane) oligomers 28 (Figure 12) were prepared by one-component polycondensation of iV-(hydroxyalkyl)-2 -oxo-1,3-diazepane-l-carboxamides, which act as intramolecular blocked isocyanates <2005PLM 1459>. These oligomers are semicrystalline materials and their melting points show the odd/even effect observed earlier for [ ]-polyamides, [ ]-polyurethanes, poly(ester amide)s, and poly (amide urethane)s. Further analysis showed that the polymers are stable up to ca. 205-230 °C, the polymers with the lower number of methylene groups in the amino alcohol decomposing at the lowest temperature. 

Carbodiimides are also used as catalysts in the formation of polyamides from dicarboxylic acids and diisocyanates. The carbodiimide catalyst is generated in situ from the diisocyanate using dimethylphospholene oxide as the catalyst. In this manner segmented thermoplastic poly(ether amides) and poly(ester amides) are obtained from the acid terminated monomers and diisocyanates by reaction polymerization processes. This reaction is best conducted in a vented extruder because carbon dioxide is the byproduct. 

The segmented polyamide elastomers are synthesized from MDI (4,4 -diisocyanato-diphenylmethane) and dicarboxylic acids and a carboxylic acid terminated aliphatic polyester, polycarbonate or polyether prepolymer with an average molecular weight of M = 500-5000. The dicarboxylic acids used as hard segment extenders are adipic and azelaic acid. Also, poly(ester amide) alloys are obtained using nylon-6,6 or polyesters (PEA/PBT). 

Compound A is a novel poly(ester amide) copolymer that can be used as a bioabsorbable coating for the controlled release of drugs. A is a copolymer of four monomers, two of which are amino acids or amino acid derivatives The body s enzymes recognize the naturally occurring amino acids in the polymer backbone, allowing for controlled enzymatic breakdown of the polymer and steady release of an encapsulated drug. Identify the four monomers used to synthesize A then use Figure 28.2 to name the two amino acids. 

Besides cyclic esters and carbonates, six-membered cyclic depsipeptides and a five-membered cyclic phosphate were subjected to lipase-catalyzed ring-opening polymerizations, yielding poly (ester amide)s190 and polyphosphate,191 respectively. High temperatures (100—130 °C) were required for the polymerization of the former monomers. 

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