Construction of composite hydrophobic coating with insulation and anti-corrosion functions using non-isocyanate polyurethane and silica aerogel

Thermal insulation and anticorrosion coatings play a critical role in safeguarding industrial equipment and infrastructure. Consequently, the development of high performance, environmentally benign hydrophobic coatings has emerged as a key research priority. Conventional polyurethane coatings rely on toxic isocyanates and petroleum-derived feedstocks, raising significant environmental and occupational health concerns. Moreover, their single-component matrix inherently limits synergistic enhancement of both thermal insulation and anticorrosion performance. To address these challenges, this study reports the design and fabrication of an environmentally friendly non-isocyanate polyurethane (NIPU) composite hydrophobic coating. Specifically, a carbamate diol (CD10) was synthesized via the reaction of bio-sourced decanediamine with propylene carbonate; subsequent modification with itaconic acid yielded the NIPU resin. The raw material propylene carbonate can be synthesized from carbon dioxide, decanediamine is derived from castor oil, and itaconic acid is obtained from citric acid. This resin was then formulated with hydrophobic silica aerogel (SA, 0-4 wt%) and titanium dioxide. Comprehensive characterization confirmed the uniform dispersion of SA within the matrix and revealed a cooperative “physical barrier thermal release” mechanism between SA and TiO 2 , which collectively enhances overall coating functionality. The optimized formulation NIPU/SA-3 (containing 3 wt% SA) demonstrated superior comprehensive performance: a thermal conductivity of 0.0478 W/(m·K) (10.1% lower than that of commercial benchmark coatings), an insulation temperature difference of 18.5°C (59.5% higher), excellent hydrophobicity (water contact angle of 120.12°), robust resistance to corrosion and weak alkaline environments, and favorable mechanical properties. This environmentally friendly composite hydrophobic coating eliminates the need for toxic isocyanates, offering a viable and environmentally benign strategy for developing multifunctional materials with combined anti-corrosion and thermal insulation properties features that hold significant practical potential in construction and industrial applications.