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Controllable Growth of Gradient Structures for Biomedical Applications

[+] Author Affiliations
Wei Zhang, Donggang Yao

Georgia Institute of Technology, Atlanta, GA

Jack G. Zhou

Drexel University, Philadelphia, PA

Paper No. NEMB2010-13122, pp. 203-206; 4 pages
doi:10.1115/NEMB2010-13122
From:
  • 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
  • Conference Sponsors: ASME Nanotechnology Council
  • ISBN: 978-0-7918-4392-5 | eISBN: 978-0-7918-3866-2
  • Copyright © 2010 by ASME

abstract

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.

Copyright © 2010 by ASME
Topics: Biomedicine

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