Structure–Property Relationships for a Series of Poly(ester amide)s Containing Amino Acids

Abstract

Poly(ester amide)s (PEAs) composed of variable diols, dicarboxylic acids, and α-amino acids were synthesized and characterized to elucidate structure–property relationships. The PEAs were synthesized using both solution and interfacial approaches to obtain varying molecular weights (MWs) and polydispersities. Studies using differential scanning calorimetry and powder X-ray diffraction revealed a range of amorphous and semicrystalline behavior that was dependent on structure. The viscosities of the PEAs as a function of temperature were studied by rheology, and phase transitions were confirmed for some polymers. Mechanical properties were also investigated, and it was found that the PEAs could be tuned to exhibit elastomeric or brittle behavior by varying both the length of the diol and the amino acid moiety. This information provides new insights into the effects of PEA structure, MW, and MW distribution on PEA properties and will aid in the design and selection of PEAs with optimal properties for targeted applications.

Poly(ester amide) particles for controlled delivery of celecoxib

“…23,24 In addition, despite the minor structural difference of containing butyl versus octyl chains in their backbones, they have been shown to exhibit different thermal and mechanical properties. 31 The T g value of 34 C for the bulk PBSe used in the current work was similar to those previously reported for this polymer (38 C-40 C). 24,31 POSe was semicrystalline in the bulk state with T m values of 106 C and 150 C similar to those previously reported.…”

“…For the current work, PBSe and POSe were selected as they are easily synthesized, and have shown promising biological properties such as high cell compatibility in previous work . In addition, despite the minor structural difference of containing butyl versus octyl chains in their backbones, they have been shown to exhibit different thermal and mechanical properties . The T g value of 34°C for the bulk PBSe used in the current work was similar to those previously reported for this polymer (38°C–40°C) .…”

“…This brings the modulus into a range similar to articular cartilage, which is desirable as the injection of high modulus materials into the joint may be expected to cause irritation. Similar trends were observed for the ultimate tensile strength, with immersion in water resulting in a ~30‐fold decrease relative to the polymer in the dry state at ambient temperature and CXB inducing a further decrease . POSe‐NDL had a higher Young's modulus and higher tensile strength in water at 37°C, which likely arises from its semi‐crystallinity in the bulk, and would not likely be reflective of the properties of the particles, which were not semicrystalline.…”

“…These tests were performed with the samples in a hydrated state at 37°C to mimic physiological conditions, particularly because water is known to have a significant plasticizing effect on amorphous polymers . Indeed, increasing the temperature to 37°C immersed in water relative to ambient temperature in the dry state lowered the Young's modulus of PBSe from ~1 GPa to 1.17 ± 0.19 MPa . The addition of CXB resulted in a further decrease in modulus to 0.83 ± 0.68 MPa.…”

Covalent drug immobilization in poly(ester amide) nanoparticles for controlled release

“…[14][15][16] The ester linkages throughout the backbone can be degraded through enzymatic or non-enzymatic hydrolysis, while the amide bonds can be degraded enzymatically. [23,24] There are several different backbone structures for PEAs, but PEAs containing a-amino acids are of particular interest because of their biomimetic nature, as a-amino acids are the main constituents of proteins. [23,24] There are several different backbone structures for PEAs, but PEAs containing a-amino acids are of particular interest because of their biomimetic nature, as a-amino acids are the main constituents of proteins.…”