HC Plastics News:

A study recently published report the synthesis of new ionic liquids crosslinked shape memory polyurethane (PU-IL) is.

The novel ionic liquid crosslinked shape memory polyurethane (PU-IL) is based on polycaprolactone diol and 4,4-methyl isocyanate (phenyl isocyanate) (MDI) to overcome the major drawbacks of conventional shape memory polyurethanes. In this case, the ionic liquid crosslinking agent in the PU-IL not only exhibited a higher shape recovery ratio (98%) but also exhibited excellent shape fixability (98%). In the second cycle of the cyclic tensile test, PU-IL showed an almost completely restored shape recovery rate while maintaining excellent shape fixability. Thermal analysis by DSC (Differential Scanning Calorimeter) demonstrated higher PU-IL shape fixability by supporting its higher crystallinity and melting enthalpy.

Reduce the glass transition temperature

Performance of the new ionic liquid crosslinked shape memory polyurethane (PU-IL) with conventional linear polyurethane (PU-BDO) using 1,4-butanediol (BDO) as a chain extender, and the use of trimethylolpropane (TMP) The properties of nonionic crosslinked polyurethane (PU-TMP) were compared. The ionic liquid as a crosslinking agent lowers the glass transition temperature (Tg), and the non-ionic crosslinking agent increases the glass transition temperature (Tg). Interestingly, the soft segmental crystallinity and melting enthalpy of PU-IL were higher than the soft segmental crystallinity and melting enthalpy of PU-BDO, while no melting or crystallization peak was observed in the DSC thermogram of PU-TMP.

Dynamic thermomechanical analysis (DMA) support

The analysis results of the DSC thermal analysis method are supported by dynamic mechanical analysis (DMA). Higher glass transition temperature (Tg), and no soft segment melting transition, indicating that the hard and soft segments in PU-TMP are completely mixed, but the ionic interactions in PU-IL limit this a little.

The SAXS analysis showed that PU-TMP did not have a scattering peak and also supported the mixing of its soft and hard segments. FT-IR spectroscopy showed that PU-BDO had stronger hydrogen bonds, followed by PU-TMP and PU-IL.

Editor in charge: Yao Chunlin

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