Soybean oil-based shape-memory polyurethanes: Synthesis and characterization

Shape-memory polymers (SMPs) have wide range of applications due to their ability to sense environmental stimuli and reshape from a temporary shape to a permanent shape. Plant oil-based polymeric materials are highly concerned in recent years in consideration of petroleum depletion and environmental pollution. However, plant oil-based polymers are rarely investigated regarding their shape-memory characteristics though bio-based SMPs are highly desired nowadays. In this study, a series of soybean oil-based shape-memory polyurethanes (SSMPUs) are prepared through a mild chemo-enzymatic synthetic route, and their properties are fully characterized with tensile testing, DSC, dynamic mechanical analysis (DMA), and shape-memory testing. Results show that SSMPUs are soft rubbers with tensile strength in the range of 1.9-2.2MPa and glass transition temperature in the range of 2-5°C, and possess good shape recoveries at RT when stretching ratio is 10, 20, and 30%, respectively. This work would promote the development of high-value-added plant oil-based shape-memory polyurethanes. Practical applications: Using annual renewable plant oil as feedstock, the synthesized SSMPUs show good shape recovery properties, which will make them applicable as potential alternatives to petroleum-based shape-memory materials. The simple and mild preparation process also contributes to the further exploration of plant oil to value-added functional materials.