Development of Biodegradable Polyesters: Study of Variations in Their Morphological and Thermal Properties through Changes in Composition of Alkyl-Substituted (ε-DL) and Non-Substituted (ε-CL, EB, L-LA) Monomers

Abstract

Three series of polyesters based on monomer combinations of ε-caprolactone (ε-CL), ethylene brassylate (EB), and l-Lactide (LLA) with the alkyl substituted lactone ε-decalactone (ε-DL) were synthesized at different molar ratios. Copolymers were obtained via ring opening polymerization (ROP) employing TBD (1,5,7-triazabicyclo-[4.4.0]-dec-5-ene), an organic catalyst which can be handled under normal conditions, avoiding the use of glove box equipment. The molar monomer composition of resulting copolymers differed from theoretical values due to lower ε-DL reactivity; their Mn and Mw values were up to 14 kDa and 22.8 kDa, respectively, and distributions were (Ɖ) ≤ 2.57. The thermal stability of these materials suffered due to variations in their ε-DL molar content. Thermal transitions such as melting (Tm) and crystallization (Tc) showed a decreasing tendency as ε-DL molar content increased, while glass transition (Tg) exhibited minor changes. It is worth mentioning that changes in monomer composition in these polyesters have a strong impact on their thermal performance, as well as in their crystallization degree. Consequently, variations in their chemical structure may have an effect on hydrolyic degradation rates. It should be noted that, in future research, some of these copolymers will be exposed to hydrolytic degradation experiments, including characterizations of their mechanical properties, to determine their adequacy in potential use in the development of soft medical devices.

Tunable Quantum Coherence of Polymer-Attached Molecular Spins (PAMS): An Example of Metal-Porphyrin-Centred Four-Arm Star-Like Polymers

“…(Figure S13) Interestingly, no melting peak was observed for Cu-THPP-PDLLA synthesized from the ROP of L - lactide. Similar results have been reported by López-González and co-workers . They found the amorphous feature of the polymer when using L -lactide monomer and TBD catalyst, suggesting the detrimental effect of TBD on the crystallinity of PLLA.…”

“…Similar results have been reported by Loṕez-Gonzaĺez and co-workers. 32 They found the amorphous feature of the polymer when using L-lactide monomer and TBD catalyst, suggesting the detrimental effect of TBD on the crystallinity of PLLA. Moins et al also reported that the polyester obtained using TBD as an achiral catalyst led to the loss of the polymer crystallinity during the polymerization at 70 °C.…”