Co-continuous phase structures of immiscible polymers can be developed under appropriate melt-blending conditions. Because of the presence of interfacial tension, such co-continuous structures start to coarsen when heated to a temperature higher than the melting/softening temperature of both phases. In this article, a systemic study of controllable growth of gradient porous structures utilizing variable coarsening rates in either a gradient temperature field or a gradient shear field is presented. Based on experimental results, the gradient of shear viscosity is identified as the mechanism for generating variable coarsening rates inside a co-continuous blend. By controllable variation of the shear viscosity distribution in a blend, a spatially varied and controllable gradient in phase structure is created. After dissolution of one of the two phases, the desired porous structure of the remaining polymer is obtained. A poly (lactic acid) (PLA)/polystyrene (PS) 50/50 wt% blend was used as a model system. By designing proper thermal and/or dynamic boundary conditions and introducing different thermal/shear rate gradients during annealing, several gradient porous structures of PLA were created.
- ASME Nanotechnology Council
Controllable Growth of Gradient Structures for Biomedical Applications
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Zhang, W, Yao, D, & Zhou, JG. "Controllable Growth of Gradient Structures for Biomedical Applications." Proceedings of the ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. Houston, Texas, USA. February 7–10, 2010. pp. 203-206. ASME. https://doi.org/10.1115/NEMB2010-13122
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