Polyisobutylene-based urethane foams. II. Synthesis and properties of novel polyisobutylene-based flexible polyurethane foams

Novel polyisobutylene-based flexible polyurethane foams (PIB–PUF) have been prepared manually by the prepolymer method using three-arm star hydroxyl-terminated polyisobutylenes (PIB–triols) and toluene diisocyanate (TDI). Solvent extraction and IR spectroscopy of PIB–PUFs indicated essentially complete crosslinking. Conventional polyether-based polyrethane foams (PE–PUFs) and polybutadiene-based polyurethane foams (PBD–PUFs) have also been prepared by the same method and select physical-mechanical properties of all these urethane foams, such as tensile strength, elongation, resilience, water permeability, hot air stability, and hydrolytic stability, have been examined and compared. Although the density of PIB–PUF is lower than that of PE–PUF, its tensile strength is superior to the latter. Elongation of PIB–PUF is almost the same as those of the other foams. The PIB–PUF exhibits low resilience which indicates good damping properties. Due to the hydrophobicity of the soft segment, PIB–PUF exhibits very low water permeability. The hydrolytic and hot air stability of PIB–PUFs are outstanding. Attempts have been made to determine gas permeabilities; however, due to the open-cell nature of the foams, these studies could not be completed. The new PIB-based urethane foams combine excellent thermal, environmental, barrier, and mechanical properties, unmatched by conventional PUFs.