Biodegradable, Wear-Resistant and Resilient Thermoplastic Polycarbonate-Based Polyurethane with Nanoscale Microphase Structure

A series of PPCDL-PEG₁₀₀₀-TPU were prepared by melting method using CO₂ based biodegradable polycarbonate diol (PPCDL) and polyethylene glycol (PEG1000) as soft segments, and hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) as hard segments. Their structure and properties were characterized to show that the products have nanoscale microphase separation, excellent wear-resistance and high resilience. PPCDL-PEG₁₀₀₀-TPUs have high tensile strength, high elongation at break, controllable hardness and excellent wear resistance when the content of hard segment is about 20%. Compared to PPCDL-TPU with only PPCDL as soft segment, the mechanical properties of TPU increase rather than decrease after the addition of PEG due to the crystallization behavior of PEG units in block copolymers. When the ratios of n_PPCDL:n_PEG are 10:1 and 4:1, the tensile strength of PPCDL-PEG₁₀₀₀-TPU reaches 27.5 MPa and 16.5 MPa (an increase of nearly 200% and 20% than PPCDL-TPU). The elongation at break reaches 1995% and 2485% (an increase of nearly 40% and 75% than PPCDL-TPU). Hardness of the prepared PPCDL-PEG₁₀₀₀-TPUs' Shore A can be controlled in range of 70~85 by regulating the addition of PEG and their glass transition temperature (Tg) decreases with the increase of the amount of PEG incorporated. All PPCDL-PEG₁₀₀₀-TPUs exhibit good wear resistance with the average Akron wear volume of 12 mm³ after 4000 cycles of experiments according to national standards. PPCDL-PEG₁₀₀₀-TPUs show a high resilience performance with a negligible change in the hysteresis loop area after six cycles of tensile stretching. Furthermore, all PPCDL-PEG₁₀₀₀-TPUs possess high thermal stability, strong hydrophobicity, and low water absorption. This material has excellent application prospects and competitiveness in footwear and shock-absorbing materials.