Hybrid Tri-Cure Organo-Silicon Coatings for Monument Preservation

Abstract

A coating system integrating three distinct chemistries was developed to protect materials used in monuments and construction. Initial curing is achieved using a UV-initiated thiol-ene reaction to form a non-impressionable/non-sticky surface. Second, amine/epoxy reactions form a firm surface adhesion and give mechanical strength through consolidation. Third, alkoxysilane sol-gel curing integrates the siloxane network while adding thermal stability, hydrophobicity, and a hardened surface. The final design utilizes a photoacid generator to increase the reaction speed of the second and third curing steps. The coating can be applied by spray, dip, or wipe on methods and exhibits a rapid non-impressionable surface (as fast as 10 min) that resists graffiti and environmental conditions, and is used and stored as a single-component system with a pot life exceeding six months. A series of experiments were used to determine the coating properties and durability, including field testing and accelerated weathering.

Enhanced dimensional stability of straw-based biocomposites modified with UV light-cured coatings

“…For improving the stability of MEMO/PVA coating, the effect of additive CS on the formation of UV-cured film on the surface of straw-based biocomposite was further accessed. After the addition of CS, the C-N stretching vibration peak at 1415 cm −1 enhanced, indicating that CS promoted the cross-linking of MEMO/PVA on the surface of biocomposite to form CS-MEMO/PVA (Sims et al 2022). The possible formation mechanism of the CS-MEMO/PVA-modified composite is shown in Fig.…”

Overview of the challenges and current solutions in organic and hybrid coatings for historical monuments and architecture

“…When used on their own, fluorocarbons exhibit hydrophobicity and chemical and biological resistances but suffer from low adhesion and prevent re-coating. Addition of the beneficial characteristics of these compounds has been successfully integrated into epoxies, [140][141][142] acrylics, [143][144][145][146][147][148] siloxanes, [149][150][151][152][153][154] urethanes, [155][156][157] and more; however, decisions to restrict the usage of perfluoro compounds by government agencies have led many scientists to look for new methods to obtain these traits in coatings. In March 2023 the US Environmental Protection Agency proposed the regulation of six perfluoroalkyl substances with anticipation to finalize the decision by the end of 2023 and a potential for additional restrictions in the future.…”

“…5). 154 Integration of epoxies, amines, and other organic groups into siloxane-based systems has resulted in solgel materials which do not crack when undergoing hydrolysis due to the added orthogonal network. 164 Siloxanes have also been combined with acrylics to achieve an increase in thermal stability and hydrophobicity 165 and with urethanes for antifouling capabilities.…”

“…5). 154 Integration of epoxies, amines, and other organic groups into siloxane‐based systems has resulted in sol–gel materials which do not crack when undergoing hydrolysis due to the added orthogonal network 164 …”

Modification of Epoxy Coatings with Fluorocontaining Organosilicon Copolymers

“…To obtain hydrophobic coating, low-surface-energy materials such paraffins [ 9 , 10 ], fluorine-containing compounds [ 11 , 12 , 13 ], organosilicon compounds [ 14 , 15 , 16 ], and fluorinated organosilicon compounds [ 17 , 18 , 19 , 20 , 21 ] can be used. However, each of them has quite significant drawbacks.…”