  Ice growth has attracted great attention for its capability of fabricating
hierarchically porous microstructure. However, the formation of tilted lamellar
microstructure during freezing needs to be reconsidered due to the limited
control of ice orientation with respect to thermal gradient during in-situ
observations, which can greatly enrich our insight into architectural control
of porous biomaterials. This paper provides an in-situ study of solid/liquid
interface morphology evolution of directionally solidified single crystal ice
with its C-axis (optical axis) perpendicular to directions of both thermal
gradient and incident light in poly (vinyl alcohol, PVA) solutions. Misty
morphology and V-shaped lamellar morphology were clearly observed in-situ for
the first time. Quantitative characterizations on lamellar spacing, tilt angle
and tip undercooling of lamellar ice platelets provide a clearer insight into
the inherent ice growth habit in polymeric aqueous systems and are suggested
exert significant impact on future design and optimization in porous
biomaterials.
