摘要
Humidity-induced self-healing offers a practical and environmentally sustainable strategy to improve material durability, yet its application in bituminous materials remains underexplored. This study presents a novel polyurethane (PU) synthesized with polytetrahydrofuran (PTMEG) as soft segments and isophorone diisocyanate (IPDI) as hard segments, combined with polar poly(N-isopropylacrylamide) (PNIPAM) to create a PU-PNIPAM copolymer featuring multiple hydrogen-bonding interactions. The PU-PNIPAM was incorporated into styrene-butadiene-styrene (SBS) modified bitumen, and rheological tests demonstrated that increasing PU-PNIPAM content enhances rutting resistance by improving creep recovery and reducing non-recoverable deformation. Optical microscopy observations under humid conditions revealed that PU-PNIPAM-modified bitumen exhibits humidity-responsive self-healing capabilities, with healing efficiency dependent on additive concentration. The humidity-induced self-healing mechanism of PU-PNIPAM was characterized by Fourier Transform Infrared Spectroscopy (FTIR), which monitored temporal evolution of the hydrogen bond index (HBI) under controlled humidity. A monotonic HBI increase confirmed aqueous hydrogen-bonding formation between PU and PNIPAM, driving autonomous repair. Water absorption and contact angle measurements revealed that despite PNIPAM-enhanced hydrophilicity of PU, incorporation of PU-PNIPAM into SBS-modified bitumen maintained bulk hydrophobicity, exhibiting water absorptivity below 1 wt% (deionized water) and 0.4 wt% (rainwater) after 4-day immersion. This strategy circumvents energy-intensive thermal healing, establishing an energy-efficient humidity-activated repair mechanism for bituminous composites. Crucially, the technology enables autonomous road maintenance in humid environments through continuous micro-crack sealing, extending service life while reducing resource consumption, maintenance frequency, and environmental footprint.
危险品化学品经营许可证（带存储）