Atomistic investigations of mechanical properties and degradation rates of polycaprolactone blends with polylactic acid and polyglycolic acid

HD Touki and NU Ahmed and M Motalab and P Bose, MATERIALS RESEARCH EXPRESS, 12, 085307 (2025).

DOI: 10.1088/2053-1591/adfad5

Polycaprolactone (PCL) is a versatile biomaterial widely recognized for its biodegradability, non-toxicity, biocompatibility, and superior blending capability. However, its moderate mechanical strength often limits broader practical applications. In this study, molecular dynamics simulations were utilized to investigate enhancements in mechanical properties (Young's modulus and ultimate tensile strength) and degradation kinetics of PCL through strategic blending with polyglycolic acid (PGA) and polylactic acid (PLA). Compositions studied included binary blends PCL/PGA (70/30) and PCL/PLA (70/30), as well as ternary blends PCL/PGA/PLA with ratios of (70/15/15), (60/20/20), and (50/25/25). PLA was selected due to its high stiffness and favorable thermal degradation properties, while PGA was chosen for its rapid degradation characteristics. The results demonstrated significant improvements; blending 30 wt% PGA into PCL notably increased ultimate tensile strength by 25.3% and Young's modulus by 34.3%. Additionally, the hydrolytic degradation behaviors of neat PCL and its blends were examined in acidic (HCl) and basic (NaOH) environments using molecular simulations with explicit water molecules. The degradation rate in basic conditions (0.94 ns-1) was notably higher compared to acidic conditions (0.33 ns-1). Importantly, the ternary blend PCL/PLA/PGA (50/25/25) exhibited nearly double the degradation rate compared to pristine PCL. Thermal degradation studies, conducted through rapid heating (100 K/ps from 300 K to 3000 K), revealed the formation of primarily low-carbon molecules as end-products. Our simulation results offers crucial design guidelines for mechanical enhancement, controlled degradation, and biocompatibility optimization of PCL, which are critical for advancing its applications in biomedical engineering, including tissue scaffolding, drug delivery systems, resorbable surgical sutures, and sustainable packaging solutions.

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