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Sol–Gel derived hybrid materials for conservation of fossils

  • Original Paper: Industrial and technological applications of sol–gel and hybrid materials
  • Published:
Journal of Sol-Gel Science and Technology Aims and scope Submit manuscript


Fossils are nonrenewable natural heritages formed by Mother Nature. After being excavated or exposed, fossils can be destroyed by weathering and water erosion. However, until now, there is very limited research work on fossil conservation. In this work, we focus on the protection of pterosaur fossils found in Hami, which are very sensitive to water. Four siloxane-based polymeric sols, including from tetraethyl orthosilicate and other three hybrid siloxane monomers, are prepared by controlled hydrolysis protocol. Their chemical and physical properties and performances as fossil protection materials are examined. Experimental data show that all sols have excellent permeabilities, decent reinforcement abilities, good resistance to light and heat aging. The organic moieties in the hybrids can also significantly increase the fossil’s hydrophobicity and reduce the cracking of the gels. The results indicate siloxane-based polymers can be very potential protection materials for fossils. And the hybrid polysiloxane sol containing epoxy function groups has overall the best performances.

Top left: severely degraded fossil due to water erosion, top right: structures of four sols Bottom: significantly improved fossil resistance to water after treated by silica sols, from left to right: treated by TEOS-TMPM-s, TEOS-TMPE-s, TEOS-BTME-s, TEOS-s and control sample.


  • Four silica sols, including three hybrids sols, are synthesized via controlled sol–gel process. Their chemical and physical properties are examined.

  • The as-prepared sols are applied to protect Hami fossils. It is the first systematic research on fossil protection.

  • Hami fossil can be protected by these silica sols nicely and among them, hybrid sol containing epoxy function groups has overall the best performances.

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  1. Janvier P (2015) Facts and fancies about early fossil chordates and vertebrates. Nature 520(7548):483–489

    Article  CAS  Google Scholar 

  2. Sayani HR, Cobb KM, Cohen AL, Elliott WC, Nurhati IS, Dunbar RB, Rose KA, Zaunbrecher LK (2011) Effects of diagenesis on paleoclimate reconstructions from modern and young fossil corals. Geochim Cosmochim Acta 75(21):6361–6373

    Article  CAS  Google Scholar 

  3. Zhang C, Guo Z, Deng C, Ji X, Wu H, Paterson GA, Chang L, Li Q, Wu B, Zhu R (2016) Clay mineralogy indicates a mildly warm and humid living environment for the Miocene hominoid from the Zhaotong Basin, Yunnan, China. Sci Rep. 6:20012

    Article  CAS  Google Scholar 

  4. Buncea M, Worthy TH, Phillips MJ, Holdaway RN, Willerslev E, Haile J, Shapiro B, Drummond A, Scofield RP, Kamp PJJ, Cooper A (2009) The evolutionary history of the extinct ratite moa and New Zealand Neogene paleogeography. Proc Natl Acad Sci USA 106(49):20646–20651

    Article  Google Scholar 

  5. Menningen J, Siegesmund S, Tweeton D, Träupmann M (2018) Ultrasonic tomography: non-destructive evaluation of the weathering state on a marble obelisk, considering the effects of structural properties. Environ Earth Sci 77(17):601

  6. Salman AB, Howari FM, El-Sankary MM, Wali AM, Saleh MM (2010) Environmental impact and natural hazards on Kharga Oasis monumental sites, Western Desert of Egypt. J Afr Earth Sci 58(2):341–353

    Article  Google Scholar 

  7. Bonazza A, Messina P, Sabbioni C, Grossi CM, Brimblecombe P (2009) Mapping the impact of climate change on surface recession of carbonate buildings in Europe. Sci Total Environ 407(6):2039–2050

    Article  CAS  Google Scholar 

  8. Cardell C, Delalieux F, Roumpopoulos K, Moropoulou A, Auger F, Van Grieken R (2003) Salt-induced decay in calcareous stone monuments and buildings in a marine environment in SW France. Constr Build Mater 17(3):165–179

    Article  Google Scholar 

  9. E. Ruiz-Agudo FM, Jacobs P, Rodriguez-Navarro C (2007) The role of saline solution properties on porous limestone salt weathering by magnesium and sodium sulfates. Environ Geol 52(2):269–281

    Article  Google Scholar 

  10. McNamara CJ, Perry TDt, Bearce KA, Hernandez-Duque G, Mitchell R (2006) Epilithic and endolithic bacterial communities in limestone from a Maya archaeological site. Micro Ecol 51(1):51–64

    Article  Google Scholar 

  11. Bracci S (2001) Lidar remote sensing of stone cultural heritage: detection of protective treatments. Optical Eng 40(8):1579–1583

  12. Xu F, Tang J, Gao S (2010) Characterization and origin of weathering crusts on Kylin carved-stone, Kylin countryside, Nanjing – a case study. J Cultural Herit 11(2):228–232

    Article  Google Scholar 

  13. Xu F, Zeng W, Li D (2019) Recent advance in alkoxysilane-based consolidants for stone. Prog Org Coat 127:45–54

    Article  CAS  Google Scholar 

  14. Temraz MG, Khallaf MK (2016) Weathering behavior investigations and treatment of Kom Ombo temple sandstone, Egypt – based on their sedimentological and petrogaphical information. J Afr Earth Sci 113:194–204

    Article  CAS  Google Scholar 

  15. Ludovico-Marques M, Chastre C (2014) Effect of consolidation treatments on mechanical behaviour of sandstone. Constr Build Mater 70:473–482

    Article  Google Scholar 

  16. Baud P, Zhu W, Wong T-F (2000) Failure mode and weakening effect of water on sandstone. J Geophys Res Solid Earth 105(B7):16371–16389

    Article  Google Scholar 

  17. Zhang H, Liu Q, Liu T, Zhang B (2013) The preservation damage of hydrophobic polymer coating materials in conservation of stone relics. Prog Org Coat 76(7–8):1127–1134

    Article  CAS  Google Scholar 

  18. Eyssautier-Chuine S, Marin B, Thomachot-Schneider C, Fronteau G, Schneider A, Gibeaux S, Vazquez P (2016) Simulation of acid rain weathering effect on natural and artificial carbonate stones. Environ Earth Sci 75(9)

  19. Delalieux F, Todorov V, Dekov VM, Grieken RV (2001) Environmental conditions controlling the chemical weathering of the Madara Horseman monument, NE Bulgaria. J Cultural Herit 2(1):43–54

    Article  Google Scholar 

  20. Maravelaki-Kalaitzaki P, Kallithrakas-Kontos N, Agioutantis Z, Maurigiannakis S, Korakaki D (2008) A comparative study of porous limestones treated with silicon-based strengthening agents. Prog Org Coat 62(1):49–60

    Article  CAS  Google Scholar 

  21. Rodrigues JD, Grossi A (2007) Indicators and ratings for the compatibility assessment of conservation actions. J Cultural Herit 8(1):32–43

    Article  Google Scholar 

  22. Franzoni E, Graziani G, Sassoni E (2015) TEOS-based treatments for stone consolidation: acceleration of hydrolysis–condensation reactions by poulticing. J Sol-Gel Sci Technol 74(2):398–405

    Article  CAS  Google Scholar 

  23. Grissom CA, Charola AE, Boulton A, Mecklenburg MF (2013) Evaluation over time of an ethyl silicate consolidant applied to ancient lime plaster. Stud Conserv 44(2):113–120

    Google Scholar 

  24. Saleh AS, Helmi FM, Monir MK, El-Banna A-FE (1992) Study and consolidation of sandstone: temple of Karnak, Luxor, Egypt. Stud Conserv 37(2):93–104

    Article  Google Scholar 

  25. Mosquera MJ, Pozo J, Esquivias L, Rivas T, Silva B (2002) Application of mercury porosimetry to the study of xerogels used as stone consolidants. J Non Cryst Solids 311(2):185–194

    Article  CAS  Google Scholar 

  26. Mosquera MJ, Pozo J, Esquivias L (2003) Stress during drying of two stone consolidants applied in monumental conservation. J Sol-Gel Sci Technol 26(1–3):1227–1231

    Article  CAS  Google Scholar 

  27. Lehmann RG, Miller JR, Kozerski GE (2000) Degradation of silicone polymer in a field soil under natural conditions. Chemosphere 41(5):743–749

    Article  CAS  Google Scholar 

  28. Liu R, Han X, Huang X, Li W, Luo H (2013) Preparation of three-component TEOS-based composites for stone conservation by sol–gel process. J Sol-Gel Sci Technol 68(1):19–30

    Article  CAS  Google Scholar 

  29. Mosquera MJ, de los Santos DM, Montes A, Valdez-Castro L (2008) New nanomaterials for consolidating stone. Langmuir 24(6):2772–2778

    Article  CAS  Google Scholar 

  30. Mosquera MJ, de los Santos DM, Valdez-Castro L, Esquivias L (2008) New route for producing crack-free xerogels: obtaining uniform pore size. J Non Crystal Solids 354(2–9):645–650

    Article  CAS  Google Scholar 

  31. Alié C, Pirard R, Lecloux AJ, Pirard J-P (1999) Preparation of low-density xerogels through additives to TEOS-based alcogels. J Non Crystal Solids 246(3):216–228

    Article  Google Scholar 

  32. Xu F, Li D, Zhang H, Peng W (2011) TEOS/HDTMS inorganic–organic hybrid compound used for stone protection. J Sol-Gel Sci Technol 61(2):429–435

    Article  Google Scholar 

  33. Zárraga R, Cervantes J, Salazar-Hernandez C, Wheeler G (2010) Effect of the addition of hydroxyl-terminated polydimethylsiloxane to TEOS-based stone consolidants. J Cultural Herit 11(2):138–144

    Article  Google Scholar 

  34. Zárraga R, Alvarez-Gasca DE, Cervantes J (2002) Solvent effect on TEOS film formation in the sandstone consolidation process. Silicon Chem 1(5–6):397–402

    Article  Google Scholar 

  35. Wang X, Kellner AWA, Jiang S, Wang Q, Ma Y et al. (2014) Sexually dimorphic tridimensionally preserved pterosaurs and their eggs from China. Curr Biol 24:1323–1330

    Article  CAS  Google Scholar 

  36. Wang X, Kellner AWA, Jiang S, Cheng X, Wang Q et al. (2017) Egg accumulation with 3D embryos provides insight into the life history of a pterosaur. Science 358:1197–1201

    Article  CAS  Google Scholar 

  37. David M, Martill (2014) Palaeontology: which came first, the pterosaur or the egg? Curr Biol 24:R615–R617

    Article  Google Scholar 

  38. Deeming DC (2017) Palaeontology: how pterosaurs bred. Science 358:1124–1125

    Article  CAS  Google Scholar 

  39. Wenhua Z, Xiangna H, Cong C, Xiaolin W (2019) Studies on salt weathering of hami fossils in Xinjiang, The 9th Graduate Student’s Forum on Archaeology in Beijing

  40. Wang S-D, Scrivener KL (2003) 29Si and 27Al NMR study of alkali-activated slag. Cem Concr Res 33(5):769–774

    Article  CAS  Google Scholar 

  41. Hall CJ, Ponnusamy T, Murphy PJ, Lindberg M, Antzutkin ON, Griesser HJ (2014) A solid-state nuclear magnetic resonance study of post-plasma reactions in organosilicone microwave plasma-enhanced chemical vapor deposition (PECVD) coatings. ACS Appl Mater Interfaces 6(11):8353–8362

    Article  CAS  Google Scholar 

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The authors thank Long Xiang, Yan Li, Yang Li, Shunxing Jiang, He Chen and Xinjun Zhang for their help in the field work. They are also grateful to the financial supports from the National Natural Science Foundation of China (51732008, 21673167, 41572020 and 41688103), the Innovation Project of Instrument and Equipment Function Development of the Chinese Academy of Sciences (No. 2060499), and the foundation of excavation and protection from the Hami government.

Author contributions

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by XP, YW and X-FM. The evaluation of fossil was performed by XP and HZ. The first draft of the manuscript was written by XP and all authors commented on previous versions of the manuscript. HB, XH, HL and XW provided the funding. All authors read and approved the final manuscript.

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Correspondence to Xiao Huang or Xiaolin Wang.

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Peng, X., Wang, Y., Ma, XF. et al. Sol–Gel derived hybrid materials for conservation of fossils. J Sol-Gel Sci Technol 94, 347–355 (2020).

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