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<p>Shape memory polyurethanes are smart materials that give back their original shape once stimulated by heat or water, rendering them ideal for certain biomedical applications such as minimally invasive surgery or drug delivery. In this research, dual-responsive SMPUs were synthesized successfully through the use of polycaprolactone (PCL) (2000/4000&#xa0;g/mol) and poly(ethylene glycol) (PEG) (400/4000&#xa0;g/mol) in a 30/70 weight ratio. Microstructural analysis showed that among all the parameters, crystallinity of the soft segments dominated in governing the elastic modulus because the crystalline regions were much stiffer than the hard segment domains. These SMPUs showed excellent mechanical properties with tensile strengths ranging from 5.8 to 11.2&#xa0;MPa and elongation at break ranging from 150 to 310%. The shape memory behavior of these SMPUs was extraordinary with shape fixity ratios of greater than 95% and recovery ratios of 98% at 65&#xa0;°C. They also attained almost 92% recovery in water at 37&#xa0;°C. Thermal analysis (DSC) revealed that the dual-responsiveness is due to a “phase-switching” mechanism where the crystalline soft segments (PCL/PEG) constitute the reversible switch that fixes the temporary shape and releases it, and the hard segments form the permanent netpoints which memorize the original shape. The improved water-driven recoveries are further correlated to the increase of the overall crystallinity (from 32% to 46%), with high polyol molecular weights that enhance the switching. Thus, these results prove the suitability of the synthesized SMPU materials for advanced biomedical applications.</p>

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The effect of the molecular weight of PEG and PCL on the physical, mechanical, and shape memory properties of polyurethane with dual-responsive behavior

  • 期刊论文

  • 发表日期：

    2026年1月8日

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  • Pooria Hoseinzadeh,
  • Zahra Telikani,
  • Fatemeh Sajedi bejandi,
  • Reza Lotfi Mayan Sofla

摘要

Shape memory polyurethanes are smart materials that give back their original shape once stimulated by heat or water, rendering them ideal for certain biomedical applications such as minimally invasive surgery or drug delivery. In this research, dual-responsive SMPUs were synthesized successfully through the use of polycaprolactone (PCL) (2000/4000 g/mol) and poly(ethylene glycol) (PEG) (400/4000 g/mol) in a 30/70 weight ratio. Microstructural analysis showed that among all the parameters, crystallinity of the soft segments dominated in governing the elastic modulus because the crystalline regions were much stiffer than the hard segment domains. These SMPUs showed excellent mechanical properties with tensile strengths ranging from 5.8 to 11.2 MPa and elongation at break ranging from 150 to 310%. The shape memory behavior of these SMPUs was extraordinary with shape fixity ratios of greater than 95% and recovery ratios of 98% at 65 °C. They also attained almost 92% recovery in water at 37 °C. Thermal analysis (DSC) revealed that the dual-responsiveness is due to a “phase-switching” mechanism where the crystalline soft segments (PCL/PEG) constitute the reversible switch that fixes the temporary shape and releases it, and the hard segments form the permanent netpoints which memorize the original shape. The improved water-driven recoveries are further correlated to the increase of the overall crystallinity (from 32% to 46%), with high polyol molecular weights that enhance the switching. Thus, these results prove the suitability of the synthesized SMPU materials for advanced biomedical applications.