Molecular dynamics simulation, synthesis and characterization of polyurethane block polymers containing PTHF/PCL mixture as a soft segment

Abstract

To understand the role of mixed soft segments (PCL/PTHF) on the microphase separation of TPUs, thermodynamic calculations, molecular dynamics (MD) simulation and experimental approaches were used. With the use of three-component Flory–Huggins model, interaction parameter and solubility parameters, the free energy of mixing of soft segments and hard segment was investigated. MD simulation was also used to evaluate different types of hydrogen bonding and segmental interactions at atomic levels. To this end, the extent of microphase separation (αsep), state of hydrogen bonding, segment melting enthalpies, crystallization process time and temperature, morphology of soft and hard phases and mechanical properties were fully characterized by ATR-FTIR, DSC, TEM, RMS and tensile techniques. Isothermal and non-isothermal examinations have shown that using mixed soft segments accelerates the microphase separation process comparing samples containing one type of polyols. Mechanical properties data showed that using mixed soft segments disallowed early failure and TPU with extreme enhanced elongation at break and toughness could be obtained.