Kinetic roughening transition of ice crystals and its implications during recrystallization

TL;DR

This study identifies a specific temperature at which ice crystal surfaces transition from rough to faceted, revealing how intrinsic kinetics and additives influence morphology, with implications for cryopreservation and interpreting ice activity.

Contribution

It demonstrates the existence of a kinetic roughening transition in ice crystals and explores how additives like antifreeze proteins affect this transition, advancing understanding of ice surface dynamics.

Findings

A kinetic roughening transition temperature of -16.0°C was identified.

AFPIII promotes faceting and raises the roughening transition temperature.

Surface morphology changes are independent of solute type.

Abstract

Hypothesis Roughening transitions at solid-liquid interfaces govern crystal morphology in diverse systems. In ice crystallization, these transitions control interfacial faceting and surface kinetics. Faceted morphologies are often associated with ice-active molecules, which inhibit recrystallization and are essential for cryopreservation. We hypothesize that kinetic roughening transitions can induce faceting even in the absence of ice-active agents, particularly at high solute concentrations with depressed melting points, potentially complicating the interpretation of crystal morphology as an indicator of ice activity. Experiments We investigated the kinetic roughening transition of ice in dimethyl sulfoxide (DMSO) and proline-water solutions using cryomicroscopy and real-time image analysis. Crystals grew in microdroplets, maintaining near-equilibrium conditions as solute concentration increased during growth due to conversion of liquid water to ice. Antifreeze protein type III (AFPIII) was applied to distinguish intrinsic roughening from adsorption-mediated effects. Findings A distinct kinetic roughening transition temperature (TR = -16.0 +/- 0.2 oC) was identified, marking a shift from rounded disks at higher temperatures to faceted hexagonal plates at lower temperatures, independent of solute type. Recrystallization below TR revealed asymmetry between growth and melting interfaces. AFPIII promoted faceting even above TR, consistent with stabilization of step edges and elevation of the roughening transition temperature. These results clarify the interplay between intrinsic interface kinetics and molecular adsorption, with implications for interpreting ice morphology, surface roughening, and cryopreservation design.