Flexible Shape Memory Structures with Low Activation Temperatures Through Investigation of the Plasticizing Effect

Lazarus E, Liu H, et al.

Materials Research Express

OcuCell Inc., Iowa State University, University of St. Thomas, University of Florida

RESEARCH SUMMARY

This study developed thermoplastic polyurethane (TPU)–polylactic acid (PLA)–polyethylene oxide (PEO) shape memory polymer (SMP) composites with tunable activation temperatures suitable for biomedical and smart structural applications. Adding PEO as a biocompatible plasticizer decreased the glass transition temperature (Tg) of the TPU/PLA blend from 62.4 °C to 34.6 °C, enabling shape recovery at near-physiological temperatures (37 °C). Bowtie honeycomb geometries fabricated from the blends achieved 86.5% shape recovery at 37 °C with 30 wt% PEO, only 5% below recovery at 50 °C, while preserving structural integrity. The study highlights the potential of PEO-plasticized SMPs for biomedical implants, deployable devices, and self-sensing structures.

Mechanical testing of TPU/PLA/PEO composites was performed using a CellScale UniVert mechanical tester (200 N load cell, Waterloo, ON, Canada) at room temperature in accordance with ASTM D638. Dumbbell specimens (2.6 ± 0.3 mm thick) were stretched at 5 mm min⁻¹ with a preload of 0.1 N. The slope of the linear region of the stress–strain curve provided the tensile modulus. UniVert results confirmed decreasing modulus and tensile strength with increasing PEO content, consistent with the plasticizing effect.

AUTHORS

Emily Lazarus; Han Liu; Thomas Secord; Simon Laflamme; Iris V. Rivero.

PUBLICATION DETAILS

JOURNAL

Materials Research Express

YEAR

2025

INSTITUTIONS

OcuCell Inc., Iowa State University, University of St. Thomas, University of Florida

COUNTRIES

United States

INSTRUMENT USED

UniVert

TESTING METHODS

Tensile Testing

RESEARCH APPLICATIONS

Electroactive and Photothermal PolymersMaterial Fatigue and DurabilityPolymers and Elastomers TestingSoft Robotics MaterialsWearable Bioelectronics

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