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Erratum published on 7 March 2018, see Materials 2018, 11(3), 389.
Open AccessArticle

Poly(hydroxyalkanoate)s-Based Hydrophobic Coatings for the Protection of Stone in Cultural Heritage

1
Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, 40131 Bologna, Italy
2
Consorzio Interuniversitario di Scienza e Tecnologia dei Materiali (INSTM), 50121 Firenze, Italy
*
Author to whom correspondence should be addressed.
Materials 2018, 11(1), 165; https://doi.org/10.3390/ma11010165
Received: 4 December 2017 / Revised: 11 January 2018 / Accepted: 17 January 2018 / Published: 20 January 2018
(This article belongs to the Special Issue Recent Advances in Smart Materials for the Built Environment)
Reversibility is a mandatory requirement for materials used in heritage conservation, including hydrophobic protectives. Nevertheless, current protectives for stone are not actually reversible as they remain on the surfaces for a long time after their hydrophobicity is lost and can hardly be removed. Ineffective and aged coatings may jeopardise the stone re-treatability and further conservation interventions. This paper aims at investigating the performance of PHAs-based coatings for stone protection, their main potential being the ‘reversibility by biodegradation’ once water repellency ended. The biopolymer coatings were applied to three different kinds of stone, representative of lithotypes used in historic architecture: sandstone, limestone and marble. Spray, poultice and dip-coating were tested as coating techniques. The effectiveness and compatibility of the protectives were evaluated in terms of capillary water absorption, static and dynamic contact angles, water vapour diffusion, colour alteration and surface morphology. The stones’ wettability after application of two commercial protectives was investigated too, for comparison. Finally, samples were subjected to artificial ageing to investigate their solar light stability. Promising results in terms of efficacy and compatibility were obtained, although the PHAs-based formulations developed here still need improvement for increased durability and on-site applicability. View Full-Text
Keywords: protectives; water repellency; bio-based biodegradable polymers; conservation; PHA; marble; limestone; sandstone protectives; water repellency; bio-based biodegradable polymers; conservation; PHA; marble; limestone; sandstone
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Andreotti, S.; Franzoni, E.; Degli Esposti, M.; Fabbri, P. Poly(hydroxyalkanoate)s-Based Hydrophobic Coatings for the Protection of Stone in Cultural Heritage. Materials 2018, 11, 165.

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