Inhibitory Mechanism of Glycerol on the Growth of Ice Crystals by Molecular Dynamics

The molecular simulations of the growth process of crystal face (020) of orthorhombic ice were performed in glycerol aqueous solutions at 225 K, 1 x 10(5) Pa in order to investigate the inhibitory mechanism of glycerol 14 ice growth. Hydrogen bond number, density profile, root mean square deviation and intermolecular radial distribution functions were calculated to study the dynamic behavior of water and glycerol molecules. The result shows that the glycerol molecules can form numerous hydrogen bonds with water molecules. And water-water hydrogen bonds decreased with the increasing concentration of glycerol. Glycerol inhibits the interaction of hydrogen bonding between water molecules and makes nucleation of ice crystal difficult. Glycerol increases the viscosity of water solution and decreases the diffusivity of water molecule from solution to ice crystal face. More important, glycerol molecules have a competitive adsorption with water molecules on the crystal face, even occupy the surface lattice site and take place two or three water molecules. This behavior can break the symmetry of ice crystal face and prevent the further growth. Therefore, glycerol can play a role in inhibiting the growth of ice crystals in both aqueous solution and crystal face. So , the current research gives a better understanding for the inhibitory mechanism of glycerol on the growth of ice crystal and provide theoretical support for optimizing the protection prescriptions of biological tissues and protein medicine.