A detailed molecular dynamics simulation study of the self-assembly, intermolecular structure and thermodynamic behavior of an aqueous solution of non-ionic surfactant octa ethylene glycoln-decyl ether (C10E8) in the presence of a non-ionic polar polymer poly(acrylic acid) PAA is presented. The aggregation numberNaggand concentration of surfactantCsin the simulation systems were varied in the range 0.01-0.32 M and 5 <Nagg< 101 (dilute to concentrated) with a dilute polymer concentration (Cp= 0.01 M). Lamellar aggregates of non-ionic surfactant in bulk aqueous solution are shown by molecular level computations for the first time. Spherical micellar aggregates and lamellar aggregates are formed at low and highNagg, respectively. The transition from the spherical micelle phase to the lamellar phase in a binary solution is captured for the first time. A conformational transition from coiled to extended PAA chains adsorbed on the surfactant aggregate occurs at a particular value ofNagg, commensurate with the transition from spherical micelle aggregates to anisotropic lamellar aggregates. Formation of the surfactant aggregate in binary and ternary solutions and the polymer-surfactant complex in a ternary solution is enthalpically favored. Adsorption of PAA on the surfactant aggregate surface is driven by hydrogen bonds (HBs) between carboxylic acid groups of PAA and ethylene oxide groups of C10E8. A significant number of HBs occur between polar oxygens of C10E8and hydroxyl oxygens of PAA. The results are in agreement with the limited available experimental data on this system. © The Royal Society of Chemistry 2020.