Lukas Benecke (Dresden, DE), Dr. Robert Tonndorf (Dresden, DE), Dr. Dilbar Aibibu (Dresden, DE), Prof. Dr. Chokri Cherif (Dresden, DE)
Abstract text (incl. figure legends and references)
INTRODUCTION
Shape-changing polymers that adapt to defects in vivo or work as actuators are extremely promising for novel therapies. They must meet a number of requirements, including biocompatibility, low activation temperatures, and high actuation forces. Therefore, this work aimed for the development of shape memory polymers (SMPs) and liquid crystal elastomers (LCEs) fibers with specifically modified activation temperatures through material design.
EXPERIMENTAL METHODS
SMPs consist of a permanent and a temporary phase for which TPU and PCL of different molecular weights were used, respectively. LCEs were prepared by hydrosilation of the elastomer PMHS and liquid crystal MBB with three different crosslinkers: 11UB, CHDM-di, and PDMS (vinyl-terminated). Thermal, mechanical, and actoric properties of SMPs and LCEs were determined by DSC and cyclic actuation measurements.
RESULTS AND DISCUSSION
For SMPs, reducing the molecular weight of the switching phase (PCL) results in a significantly lowered activation temperature. For LCEs, a correlation between molecular length of the crosslinker and activation temperature was expected, but could not be shown. However, by adjusting LC to crosslinker ratio a minimal activation temperature was achieved. The activation temperature of SMPs could be reduced significantly to ~20 °C while LCE needed >60 °C to actuate. Material composition-dependent actuation behavior of SMPs and LCEs was characterized and compared.
CONCLUSION
The generated data shows promising properties for future smart medical applications for both SMPs and LCEs. The ability to design low activation temperatures in SMPs enables applications in vivo while high actuation forces qualify LCEs for ex vivo usage.
ACKNOWLEDGMENTS
This research (projects 21022BR, 21970BR, 20322BR) is funded through the AiF within the program for supporting the "Industrielle Gemeinschaftsforschung (IGF)" from funds of the BMWK on the basis of a decision by the German Bundestag.