Aromatic triblock polymers from natural sources as protective coatings for stone surface

Aromatic triblock polymers were synthesized, characterized and tested as protective coatings for stone surfaces. Syntheses were carried out by a ring opening polymerization process from specifically synthesized monomers ((3S)-6-methyl-3-phenyl-1,4-dioxan-2,5-dione or 1,4-benzodioxepin-3-methyl-2,5-dione and a perfluoropolyether diol (Fluorolink D10-H), as chain-initiator. Polymers were characterized through spectroscopic and analytical techniques while their stability under photo-oxidative conditions was tested using a Solar-Box. An excellent stability to environmental conditions was noticed with very low degradation during accelerated ageing tests up to 1000 h, as detected by FT-IR, molecular weight, DSC and weight loss. Furthermore these polymers formed an excellent protective coating on the stone surface as shown by capillary water absorption test. Finally, as expected, very stable coatings were obtained as shown by ageing tests. The stone surface showed negligible changes of color and a good hydrorepellency confirming a good durability of treatments.