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Optimizing the Thermomechanics of Shape-Memory Polymers for Biomedical Applications

Published online by Cambridge University Press:  01 February 2011

Christopher M. Yakacki ,
Ken Gall ,
Robin Shandas ,
Alicia M. Ortega ,
Nick Willett  and
Alan R. Greenberg
Christopher M. Yakacki
Affiliation:
Department of Mechanical Engineering, University of Colorado at Boulder, 80309
Ken Gall
Affiliation:
Department of Mechanical Engineering, University of Colorado at Boulder, 80309
Robin Shandas
Affiliation:
Department of Mechanical Engineering, University of Colorado at Boulder, 80309 Division of Cardiology, The Children's Hospital, Denver, CO 80218
Alicia M. Ortega
Affiliation:
Department of Mechanical Engineering, University of Colorado at Boulder, 80309
Nick Willett
Affiliation:
Department of Mechanical Engineering, University of Colorado at Boulder, 80309
Alan R. Greenberg
Affiliation:
Department of Mechanical Engineering, University of Colorado at Boulder, 80309
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Abstract

We examine the shape-memory effect in polymer networks intended for biomedical applications. The polymers were photopolymerized from tert-butyl acrylate (tBA) with polyethyleneglycol dimethacrylate (PEGDMA) acting as a crosslinker. Three-point flexural tests were used to systematically investigate the thermomechanics of shape-storage deformation and shape recovery. The glass transition temperature (Tg) of the polymers varied over a range of 100°C and is dependent on the molecular weight and concentration of the crosslinker. The polymers show 100% strain recovery up to maximum strains of approximately 80% at low and high deformation temperatures (Td). Free strain recovery was determined to depend on the temperature during deformation; lower deformation temperatures (Td < Tg) decreased the temperature required for free strain recovery. Constrained stress recovery shows a complex evolution as a function of temperature and also depends on Td. The thermomechanical results are discussed in light of potential biomedical applications and a prototype stent that can be activated at body temperature is presented.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 855: Symposium W – Mechanically Active Materials , 2004 , W3.27
Copyright
Copyright © Materials Research Society 2005

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References

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