Ambient-Pressure Fabrication of Waterborne Polyurethane-Reinforced Silica Composite Aerogels with Enhanced Multifunctional Performance

Abstract

We developed a waterborne polyurethane (WPU)-reinforced silica aerogel composite through a sol-gel approach combined with ambient pressure drying. By systematically optimizing the WPU content, we fabricated WPU-SA composite aerogels that simultaneously achieve high mechanical strength and low thermal conductivity. Microstructural characterization via scanning electron microscopy (SEM) confirms the formation of an interpenetrating WPU-silica network, which effectively suppresses pore collapse during drying. The optimized composite with 8.0 wt% WPU loading demonstrates a exceptional thermal conductivity of 0.040 5 W/(m·K), an ultra-low density of 0.186 g/cm³, and a remarkable compressive strength of 2.21 MPa and good flame retardancy, representing a substantial improvement over pristine SA. This study provides a facile and scalable strategy for manufacturing high-performance, cost-effective aerogel thermal insulation materials with balanced mechanical and thermal properties.

Keywords

silica aerogels / waterborne polyurethane / thermal insulation material

References

[1] Zhang X, Yu J, Zhao C, et al.Elastic SiC Aerogel for Thermal Insulation: A Systematic Review[J]. Small, 2024, 20(32): 2 311 464.

[2] Pajonk G MSome Applications of Silica Aerogels[J]. Colloid & Polymer Science, 2003, 281(7):637-651.

[3] Fei J, Duan X, Luo L, et al.Grafting Methyl Acrylic onto Carbon Fiber via Diels-Alder Reaction for Excellent Mechanical and Tribological Properties of Phenolic Composites[J]. Applied Surface Science, 2018, 433: 349-357.

[4] Liu W, Zhao Z, Yuan M, et al.Theory and Experiment on SERS Sensitivity Tuning of TiO₂ Aerogels Based on Surface Oxygen Vacancy Engineering[J]. Applied Surface Science, 2024, 655: 159 561.

[5] Merillas B, Lamy-Mendes A, Villafañe F, et al.Polyurethane Foam Scaffold for Silica Aerogels: Effect of Cell Size on the Mechanical Properties and Thermal Insulation[J]. Materials Today Chemistry, 2022, 26101 257.

[6] De Pooter S, Latré S, Desplentere F, et al.Optimized Synthesis of Ambient Pressure Dried Thermal Insulating Silica Aerogel Powder from Non-Ion Exchanged Water Glass[J]. Journal of Non-Crystalline Solids, 2018, 499217-226.

[7] Chen Z, Yang T, Zhu X, et al.Facile Preparation of Bacterial Cellulose - SiO₂ Composite Aerogel with Good Mechanical Strength and Thermal Stability[J]. ChemistrySelect, 2024, 9(10): e202 304 926.

[8] Wu Q, Yang M, Chen Z, et al.A Layered Aerogel Composite with Silica Fibers, SiC Nanowires, and Silica Aerogels Ternary Networks for Thermal Insulation at High-Temperature[J]. Journal of Materials Science & Technology, 2025, 204: 71-80.

[9] Liu Y, Jasim D J, Mohammad Sajadi S, et al.A Numerical Study of External Heat Flux Effect on the Mechanical Properties of Paraffin Phase Change Material-Reinforced Silica Aerogel: A Molecular Dynamics Approach[J]. Results in Physics, 2024, 57107 404.

[10] Gu P, Lu L, Yang X, et al.Highly Stretchable Semiconducting Aerogel Films for High-Performance Flexible Electronics [J]. Advanced Functional Materials, 2024, 34(33): 2 400 589.

[11] Miao M, Yin J, Mao Z, et al. 3D-Printed Mullite - Reinforced SiC-Based Aerogel Composites[J]. Small, 2024: 2 401 742

[12] Chang M-J, Zhu W-Y, Liu J, et al.Fabrication of Elastic SiO₂ Aerogels with Prominent Mechanical Strength and Stability Reinforced by SiO₂ Nanofibers and Polyurethane for Oil Adsorption[J]. Separation and Purification Technology, 2024, 341126 914.

[13] Patil S P, Shendye P, Markert BMolecular Dynamics Simulations of Silica Aerogel Nanocomposites Reinforced by Glass Fibers, Graphene Sheets and Carbon Nanotubes: A Comparison Study on Mechanical Properties[J]. Composites Part B: Engineering, 2020, 190107 884.

[14] Li C, Chen Z, Dong W, et al.A Review of Silicon-Based Aerogel Thermal Insulation Materials: Performance Optimization through Composition and Microstructure[J]. Journal of Non-Crystalline Solids, 2021, 553120 517.

[15] Wang L, Feng J, Jiang Y, et al.Thermal Conductivity of Polyvinylpolymethylsiloxane Aerogels with High Specific Surface Area[J]. RSC Adv., 2019, 97 833-7 841.

[16] Wang R, Sun J, Zhang RSuper-Flexible and Low-Shrinkage Polyimide Aerogel Composites with Excellent Thermal Insulation: Boosted by SiO₂ Micron Aerogel Powder[J]. Materials Letters, 2024, 371136 882.

[17] Sun J, Yao K, Zhang RRobust-Flexible and Highly-Thermostable Polyimide-Silica Aerogels with Adjustable Fiber Skeleton Structure for Efficient Aerospace Thermal Protection[J]. Materials Today Communications, 2024, 39109 409.

[18] Pinilla-Peñalver E, Fresno Ó, Cantero D, et al.Enhancing Flame-Retardant Properties of Polyurethane Aerogels Doped with Silica-Based Particles[J]. Gels, 2024, 10(7): 465.

[19] Xu Q, Gao S, Diao Z, et al.Phenolic Modified Aerogel as a Hybrid Thermal Insulation Systems[J]. Langmuir, 2025, 41(11):7 592-7 604.

[20] Chen Y X, Klima K M, Brouwers H J H, et al.Effect of Silica Aerogel on Thermal Insulation and Acoustic Absorption of Geopolymer Foam Composites: The Role of Aerogel Particle Size[J]. Composites Part B: Engineering, 2022, 242110 048.

[21] Xi S, Wang Y, Zhang X, et al.Fire-Resistant Polyimide-Silica Aerogel Composite Aerogels with Low Shrinkage, Low Density and High Hydrophobicity for Aerospace Applications[J]. Polymer Testing, 2023, 129108 259.

[22] Niu Q, Yue X, Guo Z, et al.Flame Retardant Bamboo Fiber Reinforced Polylactic Acid Composites Regulated by Interfacial Phosphorus-Silicon Aerogel[J]. Polymer, 2022, 252124 961.

[23] Han Y, Wu Y, Huang S, et al.Rapid Ambient Pressure Drying Preparation of Bulk ZrO₂-SiO₂ Aerogels with High Thermal Stability[J]. Ceramics International, 2024, 50(22): 48 011-48 020.

[24] Liu S, Luo D, He M, et al.In Situ Crosslinking of Silica Aerogel with Reactive Carbon Fiber for High Mechanical Property, Thermal Insulation and Superhydrophobicity[J]. Microporous and Mesoporous Materials, 2024, 377113 203.

[25] He Y, Zhang Z, Ma H, et al.Waterborne Polyurethane/Cellulose Composite Aerogel with Passive Cooling and Thermal Insulation Properties [J]. Journal of Applied Polymer Science, 2024, 141(44): e56 158.

[26] Zhu W, Wang H, Ji H, et al.Lightweight Aerogel-like Silicon Oxycarbide Ceramics with Directionally Honeycomb-like Structure for High Temperature Environments[J]. Journal of the European Ceramic Society, 2024, 44(6):4 027-4 035.

[27] Wang F, Xu Z, Chen L, et al.Super Absorbent Resilience Antibacterial Aerogel with Curcumin for Fresh Pork Preservation[J]. Food Control, 2024, 159110 289.

[28] Błaszczyński T, Ślosarczyk A, Morawski MSynthesis of Silica Aerogel by Supercritical Drying Method[J]. Procedia Engineering, 2013, 57200-206.

[29] Wang C, Huang M, Ruoff R SGraphene Oxide Aerogel ‘Ink’ at Room Temperature, and Ordered Structures by Freeze Casting[J]. Carbon, 2021, 183: 620-627.

[30] He S, Zhang X, Wu X, et al.Theoretical Study of Heat Transfer Model of Silica Aerogel Based on the Porous Structure of Secondary Particles[J]. Applied Thermal Engineering, 2024, 238: 121 935.

[31] Huang X, Liu Z, Xia W, et al.Alkylated Phase Change Composites for Thermal Energy Storage Based on Surface-Modified Silica Aerogels [J]. Journal of Materials Chemistry A, 2015, 3(5): 1 935-1 940.

[32] Yang Y, Yang Y, Ye L, et al.Microphase Separation Regulation of Polyurethane Modified Phenolic Resin Aerogel to Enhance Mechanical Properties and Thermal Insulation[J]. Chemical Engineering Journal, 2024, 495153 532.

[33] He Y, Zhang Y, Xu X, et al.Enhancement on the Thermal and Tribological Behaviors of Polyurethane/Epoxy-Based Interpenetrating Network Composites by Orientationally Aligned CNF/MXene/WPU Aerogels[J]. Composites Part A: Applied Science and Manufacturing, 2024, 187108 477.

[34] Zheng Y, Chen W, Wang Z, et al.Polystyrene/rGO Composites with Orientation-3D Network Binary Structure and Its Surprising Conductivity[J]. Macromolecules, 2018, 51(20): 7 993-8 000.

[35] Shahzamani M, Bagheri R, Masoomi MSynthesis of Silica-Polybutadiene Hybrid Aerogels: The Effects of Reaction Conditions on Physical and Mechanical Properties[J]. Journal of Non-Crystalline Solids, 2016, 452325-335.

[36] Wang T, Xu J, Zhan Y-j, et al.Organic Solvents-Free and Ambient-Pressure Drying Melamine Formaldehyde Resin Aerogels with Homogeneous Structures, Outstanding Mechanical Strength and Flame Retardancy[J]. International Journal of Biological Macromolecules, 2024, 273132 811.

[37] Baskaran K, Ali M, Gingrich K, et al.Sol-Gel Derived Silica: A Review of Polymer-Tailored Properties for Energy and Environmental Applications[J]. Microporous and Mesoporous Materials, 2022, 336111 874.

[38] Guo B F, Wang Y J, Qu Z H, et al.Hydrosilylation Adducts to Produce Wide-Temperature Flexible Polysiloxane Aerogel under Ambient Temperature and Pressure Drying[J]. Small, 2023, 20(14): 2 309 272.

[39] Zhang X, Gao Y, Wang X, et al.A Flexible, Thermal-Insulating, and Fire-Resistant Bagasse-Derived Cellulose Aerogel Prepared via a Refrigerator Freezing Combined Ambient Pressure Drying Technique[J]. Chemical Engineering Journal, 2024, 498155 466.

[40] Yang Z, Hu Q, Wang L, et al.Recent Advances in the Synthesis and Application of Graphene Aerogel and Silica Aerogel for Environment and Energy Storage: A Review[J]. Journal of Environmental Management, 2025, 377124 668.

[41] Jia X, Zhou Z, Guo D, et al.Low-Density, Large-Sized SiCnw/SiOC Composite Aerogels with Excellent Thermal Insulation, Microwave Absorption, and Thermostability[J]. Ceramics International, 2024, 50(18):33 315-33 324.

[42] Yu D, Liu M, Xu F, et al.Structure Tailoring and Thermal Performances of Water Glass-Derived Silica Aerogel Composite with High Specific Surface Area and Enhanced Thermal Stability[J]. Journal of Non-Crystalline Solids, 2024, 630122 889.

[43] He P, Pan Y, Yan M, et al.Super Thermal Insulation SiC Aerogel with High Elasticity and Good Adsorption Performance Prepared by Constructing Coaxial Precursor[J]. Composites Part A: Applied Science and Manufacturing, 2024, 181108 153.

Rights & permissions

Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature