Effect of Soft Segment Structures on the Properties of Self-Healing Photopolymerizable Thiocarbamate-Based Polyurethanes

Three self-healing photopolymerizable thiocarbamate-based polyurethane oligomers were synthesized using different macromolecular chain extenders: polypropylene glycol (PPG-1000), polytetrahydrofuran (PTMG-1000), and polycaprolactone glycol (PCL-1000). The variations in the soft segment structures had minimal impact on the double bond conversion and gel fraction of the light-cured self-healing thiocarbamate-based polyurethane materials, achieving double bond conversion rates and gel fractions exceeding 87%. Incorporating polycaprolactone diol as the soft segment improved heat resistance and tensile stress but reduced the material's self-healing ability. Conversely, utilizing polytetrahydrofuran as the soft segment resulted in outstanding overall performance, notably lowering the glass transition temperature to −48.4°C, increasing tensile strain to 1280%, achieving a self-healing efficiency of up to 90%, and exhibiting good degradation properties.