Dendritic Morphology and Growth Inhibition of Ice Crystals in Sucrose Solutions

The impact of freeze-concentrated solutes on ice crystal growth is not well understood in pharmaceutical processes. We present a quantitative analysis of the inhibition of anisotropic growth of ice crystals in sucrose solutions by combining the phase-field method and the Flory- Huggins solution theory. To better understand the driving mechanisms underlying the dendritic morphology and the freeze-concentration effect, the diffusion-partition coupling and the anisotropic interfacial energy are integrated using the thermodynamic approach. The computational results indicate that the sucrose in an aqueous solution inhibits or slows down the growth of ice crystals while enhancing the degree of branching due to the interfacial instability promoted by segregated solutes. Meanwhile, a self-similar dendritic pattern is found by covarying the initial solute concentration and the degree of supercool. The analysis and computational results are consistent with the experimental observations.