Construction of stimuli-responsive and mechanically-adaptive thermoplastic elastomeric materials

The stimuli-responsive systems present in nature have inspired scientists to develop new-generation synthetic mechano-adaptive materials for various technological applications. In this work, an effective strategy was adopted to construct a biomimetic mechano-adaptive thermoplastic elastomeric material, whose mechanical properties can be stimulated by water. The inherent ability of calcium sulphate (CaSO4) to reversibly alter its crystal structure by the hydration/dehydration process was exploited in a technologically compatible hydrophilic thermoplastic elastomeric (TPE) blend by dispersing it as a phase responsive filler. Significant enhancements in the mechanical properties were then achieved in the water-treated CaSO4 filled TPE composite. The improved mechanical properties of the water-treated composite originated with the creation of in-situ hydrated nanosized CaSO4 crystals were also correlated with the strong filler-filler interactions and higher aspect ratio of the filler. The storage modulus (dynamic stiffness) of the resulting TPE composite could be reversibly altered from-9.6 to-46.7 MPa. Most importantly,-92% mechanical adaptivity of the resulting TPE composite was achieved due to the reversible transformation of nanosized crystals into a hemihydrate mesocrystalline form by exploiting the hydration/dehydration process. The alteration of in-situ polymorphic CaSO4 phase morphological structures was verified using transmission electron microscopy, Raman spectroscopy and X-ray diffraction. This technique provides a unique pathway for the creation of next-generation stimuli-responsive TPE materials by controlling the polymorphic phase morphological structure of mineral filler.

Automated summary

The researchers successfully developed a biomimetic mechano-adaptive thermoplastic elastomeric material that can improve its mechanical properties through water stimulation. The improved mechanical properties were achieved through the formation of nanosized CaSO4 crystals and strong interactions between the filler particles. This technique allows for reversible changes in the TPE material's dynamic stiffness.