Click-Synthesized Triazole-Containing Poly(ester amide)s: Structure–Property Relationships, Limited Degradability and Nanoparticle Formation

Triazole-containing poly(ester amide)s were synthesized by a one-pot Cu(I)-catalyzed click step-growth polymerization using adipate-based dipropargyl esters and in situ generated diazide monomers derived from aliphatic diamines. Two polymers differing in the length of the polymethylene segment of the diamine unit (six and ten methylene groups) were obtained with yields close to 50% and molecular weights typical of step-growth polymerizations. FTIR and NMR analyses confirmed the formation of the expected polymer structures incorporating 1,2,3-triazole rings. Despite the complexity of the repeat unit, both polymers were semicrystalline and exhibited high glass transition and melting temperatures, reflecting strong intermolecular interactions associated with amide and triazole groups. Thermal stability and processability were strongly dependent on the diamine spacer length, with the longer polymethylene segment allowing melt processing without significant degradation. The polymers displayed good in vitro cytocompatibility and were suitable for the preparation of stable nanoparticles with narrow size distributions and negative zeta potentials around −30 mV. Degradation studies revealed low hydrolytic and enzymatic degradability under physiological conditions, in contrast to previously reported polyester analogues. These results highlight the potential of triazole-based poly(ester amide)s as biocompatible materials with potential interest for biomedical applications.