Unveiling the Role of Molecular Structure in Microscopic Thermodynamics: Insights from Probing Trapped Nanoparticles with Femtosecond Optical Tweezers

Microscopic thermodynamic studies can elucidate specific molecular interactions. In this work, the microscopic thermodynamics in binary liquid mixtures is reported, which elucidate the role of molecular structure in nonlinear solvent response using femtosecond optical tweezers (FOT). The excess thermodynamics property of mixing in various Newtonian liquid mixtures is obtained by analyzing Microrheology data from FOT. Using the noninvasive 780 nm pulse laser, micrometer‐sized particles are trapped to show how excess viscosity and residual Gibbs free energy change due to mixing. Furthermore, this study establishes that hydrocarbon chain length and branching can modulate microscopic thermodynamics through intermolecular interaction. Thus, this work sheds light on the relationship between thermodynamic properties and viscosity, which is immensely important for predicting transport properties, mixing, and chemical reactions.