New Unsaturated Biodegradable Poly(ester amide)s Composed of Fumaric Acid, L-leucine and α,ω-Alkylene Diols

Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amide)s

“…The polymers can be used as biodegradable carriers for covalent attachment biochemicals through sulfhydryl or amino groups, or to transform into various functional polymers: polyols, polyacids or polyamines by interaction with corresponding thiol or amino reagents; the former gave a much higher degree of transformation (90%–95% vs. 23%–24%) [260]. …”

New amino acid based biodegradable poly(ester amide)s via bis-azlactone chemistry

“…The TDADEs were synthesized according to Scheme 3, as described previously [25,26] and their characteristics were in full accordance with the reported data [25,26]. The HDA was used as free base (as purchased).…”

“…These polymers combine all advantages of "parent polymers" -aliphatic polyesters and polyamides: ability of biodegradation with a reasonable rate that comes from polyesters, along with a high affinity to and, hence, good compatibility with tissues and a wide range of desired mechanical properties that comes from polyamides. The scopes of applications of AABB PEAs and related polymers can substantially be expanded by their functionalization through the incorporation of various groups and sites into the backbones or lateral chains [11][12][13][14]. One of the most facile ways to render polymers functional is the incorporation of hydrophobic fragments into the macromolecules [15].…”

“…For incorporating ester linkages into the polymeric backbones one of the most convenient monomers are amino acid based diamine-diesters [1] -bis-(α-amino acid)α,ω-alkylene diesters which are normally used as stable di-p-toluenesulfonic acid salts. These salt monomers, referred below as TDADEs, represent key compounds for synthesizing all classes of AABB ester polymers reported previously [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

“…In other words, to replace a part of BAL with NPS or a part of TDADE (salt monomer) by HAD (free base). The reason of these replacements was as follows: (a) p-Nitrophenyl esters of carboxylic acids are less prone to side reactions with tertiary amines in polar aprotic solvents[27] and led to high-molecular-weight PEAs after the SGP in DMA in the presence of TEA[25,26]; we assumed, that diminishing the BAL's mole-portion in the SGP by substituting with corresponding mole-equivalent of NPS will decrease the contribution of possible side reactions, e.g. depicted inFig.…”