(169dk) Temperature-transferable Coarse-grained model for Studying Pluronic Triblock Copolymers

Pluronics are a class of triblock copolymers consisting of central hydrophobic propylene oxide (PO) blocks flanked by two hydrophilic ethylene oxide (EO) blocks. This amphiphilic nature makes Pluronics thermos-responsive, enabling their use in various industries, including wastewater treatment and drug delivery. However, the underlying dependence of thermo-responsive behaviors, such as critical micelle temperature (CMT), on the copolymers' composition or size remains unclear. Although atomistic-scale modeling is an appropriate approach to understand the underlying physics of the temperature-dependent micellization of Pluronics, its time and length scale limitations prevent it from capturing the complex micellization process, which typically occurs on the microsecond scale.

Thus, in this study, we adopted a coarse-grained molecular dynamics simulation approach using the MARTINI force field to understand the impact of temperature on the micellization of Pluronics, varying in size and composition. Since temperature-transferability is a widely known limitation of the MARTINI force field, we developed a temperature-dependent interaction between the Pluronic blocks and water blocks to overcome this limitation. The resulting coarse-grained model was able to capture the CMT of 6 Pluronics by forming micelles above CMT and remaining as unimers below CMT. The simulation findings were used to predict the CMT of various Pluronics based on their molecular weight and composition, successfully predicting the CMT of 11 Pluronic systems with a mean absolute error of 1.75°C.