Structure Property Relationship of Micellar Waterborne Poly(Urethane-Urea): Tunable Mechanical Properties and Controlled Release Profiles with Amphiphilic Triblock Copolymers

Waterborne polyurethane (WPU) has attracted significantinterestas a promising alternative to solvent-based polyurethane (SPU) dueto its positive impact on safety and sustainability. However, significantlimitations of WPU, such as its weaker mechanical strength, limitits ability to replace SPU. Triblock amphiphilic diols are promisingmaterials to enhance the performance of WPU due to their well-definedhydrophobic-hydrophilic structures. Yet, our understandingof the relationship between the hydrophobic-hydrophilic arrangementsof triblock amphiphilic diols and the physical properties of WPU remainslimited. In this study, we show that by controlling the micellar structureof WPU in aqueous solution via the introduction of triblock amphiphilicdiols, the postcuring efficiency and the resulting mechanical strengthof WPU can be significantly enhanced. Small-angle neutron scatteringconfirmed the microstructure and spatial distribution of hydrophilicand hydrophobic segments in the engineered WPU micelles. In addition,we show that the control of the WPU micellar structure through triblockamphiphilic diols renders WPU attractive in the applications of controlledrelease, such as drug delivery. Here, curcumin was used as a modelhydrophobic drug, and the drug release behavior from WPU-micellar-baseddrug delivery systems was characterized. It was found that curcumin-loadedWPU drug delivery systems were highly biocompatible and exhibitedantibacterial properties in vitro. Furthermore, the sustained releaseprofile of the drug was found to be dependent on the structure ofthe triblock amphiphilic diols, suggesting the possibility of controllingthe drug release profile via the selection of triblock amphiphilicdiols. This work shows that by shedding light on the structure-propertyrelationship of triblock amphiphilic diol-containing WPU micelles,we may enhance the applicability of WPU systems and move closer torealizing their promising potential in real-life applications.