High Efficiency Fluorinated Oligo(ethylenesuccinamide) Coating for Stone

Mara Camaiti,Antonella Salvini,Leonardo Brizi,Yijian Cao,Alessandra Papacchini,Villiam Bortolotti

doi:10.3390/coatings11040452

Abstract

The protection of stone cultural assets is related to the transformation of the surface characteristic from hydrophilic to hydrophobic/superhydrophobic through the application of a coating. The suitability of a coating depends not only on its capability to dramatically change the surface wettability, but also on other parameters such as the modification of kinetics of water absorption, the permanence of vapor diffusivity, the resistance of the coating to aging and the low volatile organic compound emissions during its application. In this work, an oligo(ethylensuccinamide) containing low molecular pendant perfluoropolyether segments (SC2-PFPE) and soluble in environmentally friendly solvents was tested as a protective agent for historic stone artifacts. Magnetic resonance imaging and relaxometry were employed to evaluate the effects of the surface wettability change, to follow the water diffusion inside the rock and to study the porous structure evolution after the application of SC2-PFPE. A sun-like irradiation test was used to investigate the photo-stability of the product. The results demonstrate that the highly photo-stable SC2-PFPE minimizes the surface wettability of the stone by modifying the water sorptivity without significantly affecting its porous structure and vapor diffusivity. The improved performance of SC2-PFPE in comparison to other traditional coatings makes it a potential candidate as an advanced coating for stone cultural heritage protection.

Highlights

Introduction published maps and institutional affilThe preservation of historical buildings and outdoor cultural assets should be a socioeconomic priority because they are the historic-cultural testimony of our past, as well as economic resources for the present time [1]
SC2-PFPE was evaluated by determining possible changes of the protective efficacy by capillary water absorption tests, and by the color test, to determine the chromatic parameters probably associated with changes of both chemical and physical properties
The new oligo(ethylensuccinamide) containing low molecular weight pendant perfluoropolyether segments shows suitable characteristics to be used as a protective agent for stone materials

Summary

Introduction

The preservation of historical buildings and outdoor cultural assets should be a socioeconomic priority because they are the historic-cultural testimony of our past, as well as economic resources for the present time [1]. Stone is one of the most important porous materials for most of these artifacts. The main causes of stone degradation are linked to chemical-physical processes involved in the ingress and diffusion of water (liquid or vapor) into the porous structure [2,3]. CO2 and pollutants from the atmosphere causing acidic corrosion of the stone and/or its binder [4,5,6,7,8], and it is responsible for internal mechanical stresses caused by hydric dilation [9], freezing-thawing cycles [10,11] and/or salt crystallization [8,12,13,14]. It has been demonstrated that the efficiency and iations

Methods

Results

Conclusion