Quantitative prediction of molecular miscibility in dextran systems as model carbohydrate polymers

This paper demonstrates the application of an advanced thermodynamic model to quantitatively predict molecular miscibility in model carbohydrate mixtures. It adds onto our previous paper on application of original Flory–Huggins theory that did not enable successful prediction of miscibility in dextran systems. In the current paper, Painter–Coleman association model was examined with its capability to account for strong hydrogen-bonding interactions on miscibility. Thermodynamics of mixing (free energy of mixing and its 2nd derivative, enthalpy and entropy of mixing, free energy of hydrogen-bonding contribution) were calculated using Miscibility Guide and Phase Calculator Software. It was quantitatively demonstrated that hydrogen-bonding significantly contributed to predictive miscibility in carbohydrate blends. When hydrogen bond formation of pentanol (an analogue compound for which hydrogen-bonding was previously characterized by Painter–Coleman group) was approximated to the hydrogen bond formation in dextrans, miscibility was successfully predicted. The generated knowledge is a step forward for understanding the thermodynamic basis for miscibility/immiscibility in carbohydrate polymer blends.