319 Steidle Building
University Park, PA 16802
Tel: 814-863-2749
Fax: 814-865-2917
Email: runt@ems.psu.edu
Dr. Runt's main areas of interest are biomedical poly(urethanes) and crystalline polymers. In collaboration
with colleagues at Penn State's Hershey Medical Center, a portion of his research group has been investigating
poly(urethaneureas) [PUU] for use as blood contacting materials in left ventricular assist devices and in the Penn
State total artificial heart. In an attempt to improve the barrier properties of these materials, a series of amphiphilic
copolymers have been synthesized that consist of a PUU backbone and various concentrations of poly(isobutylene)
combs. The chemistry of these new polymers have been studied using solid state 13C NMR and FTIR spectroscopies,
as well as extraction experiments. The barrier properties to water and air are under investigation using sorption
and permeation techniques. Characterization of the relatively complex phase-separated structure is also being conducted.
Poly(urethaneureas) are multiblock copolymers that consist of both 'hard' and soft' segments. Phase separation that occurs when PUUs are cooled from the melt or cast from solution is the primary determinate of ultimate physical properties. In a second investigation, well-defined poly(urethaneureas) with hard segment contents ranging from 13% to 48% by weight have been synthesized, along with a series of copolymers at fixed hard segment content but with different hard segment chemistry. NMR and FIFIR spectroscopies are being used to characterize chain chemistry, with small-angle x-ray scattering the principle probe of (micro)phase separated structure.
Finally, the stability of PUUs is obviously of paramount importance in biomedical applications. In this context, the in vivo and in vitro stability of 'neat' and modified PUUs are under investigation in order to access their viability as candidates for biomedical devices. A battery of experimental probes including scanning electron microscopy and x-ray photoelectron spectroscopy have been used to characterize the bulk and surface properties of explanted and control blood sacs.
L. Wu, D. Weisberg, J. Runt, G. Felder, A. Snyder and G. Rosenberg. 1999. An Investigation of the In Vivo Stability of Poly(ether urethaneurea) Blood Sacs. J. Biomed. Mater. Res. 44: 37 1.
D. Weisberg, G. Rosenberg, A. Snyder and J. Runt. 1999. Characterization of New Poly(ether urethaneurea)-comb-Poly(isobutylene) Copolymers, Trans. Soc. Biomaterials, April, 1999.
J. Huang, M. S. Lisowski, J. Runt, E. Hall, N. Buehler, R. Kean and J. S. Lin. 1998. Crystallization and Microstructure of Poly(lactide) Copolymers. Macromolecules 3 1: 2593.
L. Wu, M. S. Lisowski, S. Talibuddin and J. Runt. 1999. Crystallization of Poly(ethylene oxide) and Melt-Miscible PEO Blends. Macromolecules 32, 1576.
S. Talibuddin, J. Runt, L. Z. Liu and B. Chu. 1998. Microstructure Development and Crystallization of Poly(ethylene oxide) and Melt-Miscible PEO Blends. Macromolecules 31: 1627.