One-way and reversible dual-shape effect of polymer networks based on polypentadecalactone segments

Int J Artif Organs. 2011 Feb;34(2):231-7. doi: 10.5301/ijao.2011.6424.

Abstract

A series of degradable polymer networks containing poly(ω-pentadecalactone) (PPD) switching segments showing a thermally-induced shape-memory effect were synthesized by co-condensation of PPD-macrotriols or -tetrols with an aliphatic diisocyanate. Thermal and mechanical properties at different temperatures were explored for polymer networks as a function of crosslink density by varying the polymer chain segment length or the netpoint functionality. All polymer networks exhibited excellent shape-memory properties with shape recovery rates Rr between 99% and 100% determined in the 5th cycle under stress-free conditions. Furthermore, the polymer networks were capable of a reversible dual-shape effect based on crystallization induced elongation (CIE) and melting-induced contraction (MIC) in cyclic, thermomechanical experiments under constant stress. In these tests, the polymer networks were capable of a shape-change of 130%. The associated temperatures at which CIE or MIC occurred (TCIE and TMIC) were shown to be a function of the applied stress. By an increase of stress of 1.6 MPa, TCIE could be increased by 10 K.

MeSH terms

  • Cross-Linking Reagents / chemistry
  • Crystallization
  • Lactones / chemistry*
  • Models, Chemical
  • Molecular Structure
  • Polyesters / chemistry*
  • Stress, Mechanical
  • Temperature
  • Tensile Strength

Substances

  • Cross-Linking Reagents
  • Lactones
  • Polyesters