Epoxidized soybean oil (ESO) and isopropanolamine were used to synthesize a new polyol mixture for preparation of bio-based polyurethanes. The chemical synthetic route for reaction of ESO with isopropanolamine was analyzed by ¹H-NMR. The results suggested that both ester groups and epoxy groups in ESO had reacted with amino group of isopropanolamine through simultaneous ring-opening and amidation reactions. Epoxy groups in various situations exhibited different reactivity, and the unreacted epoxy groups were further opened by hydrochloric acid. The synthesized polyol mixture had high hydroxyl number of 317.0 mg KOH/g. A series of polyurethanes were prepared by curing the synthesized polyol mixture with 1,6-diisocyanatohexance along with different amount of 1,3-propanediol (PDO) as chain extender. Tensile tests showed that yield strengths of the polyurethanes ranged from 2.74 to 27.76 MPa depending on the content of PDO. Differential scanning calorimetry analysis displayed one glass transition temperature in the range of 24.4–28.7°C for all of the polyurethane samples, and one melt peak at high content of PDO. Thermogravimetric analysis showed that thermal degradations of the polyurethanes started at 240–255°C. In consideration of simple preparation process and renewable property of ESO, the bio-based polyurethane would have wide range of applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Biobased polymeric materials are gaining increasing attention in biomedical areas. Here, we report a new class of biocompatible polyurethanes prepared from soybean oil-based polyol that was synthesized by ring-opening reaction of epoxidized monoglyceride (EMG) with lactic acid. By adjusting the molar ratio of hydroxyl to isocyanate group and the content of chain extender, soybean oil-based polyurethanes with tensile strength of 9.30–27.1 MPa and elongation at break of 74.1–110.7% were prepared, while usual lipid-based polyurethanes with the same 1,6-diisocyanatohexane as reactant hardly have tensile strength higher than 5 MPa. Mouse fibroblast cells (L-929) showed good adhesion and growth behavior on the polyurethane samples with more hydrophilic surfaces, and the cell viabilities of more than 50% were achieved with commercial tissue culture polystyrene (TCPS) disk as control. The good mechanical property and biocompatibility of the soybean oil-based polyurethanes will make them suitable for wide range of potential biomedical applications.

Practical applications: The synthesized soybean oil-based polyurethanes have adjustable tensile strengths from 9.30–27.1 MPa and elongation at break of 74.1–110.7%. Along with their good biocompatibility, the polyurethanes can potentially replace wide range of part of petroleum-based polymeric materials, particularly as biomedical materials.

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 1.9–2.2 MPa 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.