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Preparation of a unique, multihollow-core honeycomb structure via the unidirectional freezing of a binary solvent system



Unidirectional freezing is a simple and environmentally friendly method for preparing polymeric porous materials from polymer solutions for use in various applications. In this study, a unique, multihollow-core honeycomb structure was prepared from diurethandimethacrylate (DUDM) in a 1,4-dioxane (Dx) and tertiary butanol (TBA) binary solvent system via unidirectional freezing, subsequent photopolymerization and freeze-drying. The multihollow-core honeycomb consists of two different hollow tubular structures: one structure is noncircular with an atypical cross-sectional area, and the other is circular and measures approximately 5–10 μm in diameter. Both structures are aligned parallel to the freezing direction. These hollow structures were formed by using the sequential growth of Dx and TBA crystals as a template. During the unidirectional freezing process, the Dx crystals grew in the solution along the freezing direction and expelled DUDM and TBA from its crystalline phase into the solution. When the freezing temperature was further decreased, small, needle-shaped TBA crystals grew along the freezing direction and were confined by the Dx crystals. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013