Preparation and study of polydimethylsiloxane/polytetrahydrofuran blended soft-segment-based passive cooling polyurethane materials

This study introduces a series of novel passive-cooling polyurethane materials (SiTPUs) by incorporating hydroxybutane-terminated polydimethylsiloxane (OH-PDMS)/polytetrahydrofuran (PTMG)-mixed soft segments. Wide-angle x-ray scattering (WAXS) and small-angle x-ray scattering (SAXS) analyses revealed that with an increase in the OH-PDMS content, the material exhibited enlarged grain sizes, reduced crystallinity, and the formation of larger-sized microphase “structures with different compatibilities. The sample with a PDMS proportion of 40% (SiTPU-40) demonstrates outstanding passive cooling performance, achieving a reflectance of 70.2% in the solar spectrum and a high atmospheric window emissivity of 91.6% without needing metal additives, resulting in a cooling effect of 10.8°C compared with that of pure thermoplastic polyurethane (TPU). Static contact angle tests indicated that introducing OH-PDMS considerably enhanced the self-cleaning performance of the material, with a PDMS proportion of 50% (SiTPU-50) achieving the highest contact angle of 112°. Overall, this multi-soft segment design optimizes passive cooling performance and enhances self-cleaning capabilities, thus offering new possibilities for extensive material applications, especially in wearable technology and architectural surface coatings.