Synthesis and evaluation of fluorosilicone‐modified starch for protection of historic stone

Abstract

Starch is sensitive to moisture and is weak to durability in the protection application to ancient relics. Therefore, two fluorosilicone-modified starches are firstly prepared and evaluated for the protection of historic stones. The fluoro-silicone copolymer grafted starch of P(VTMS/12FMA)-g-starch is synthesized by grafting copolymer of vinyltrimethoxysilane (VTMS) and dodecafluoroheptyl methacrylate (12FMA) onto starch. While the fluoro-silicone starch latex of VTMS-starch@P(MMA/BA/3FMA) is obtained by emulsion polymerization of VTMS primarily grafted-starch (VTMS-starch) with methyl methacrylate (MMA), butyl acrylate (BA) and 2,2,2-trifluoroethyl methacrylate (3FMA). The grafting fluorosilicone copolymer onto starch improves obviously their hydrophobic and thermal properties. Comparatively, VTMS-starch@P(MMA/BA/3FMA) film performs higher water contact angle (107 ) and thermal stability (350-430 C) than p(VTMS/12FMA)-g-starch film (72 , 250-420 C) due to the migration of fluorine-containing group onto the surface of film during the film formation. Therefore, VTMS-starch@P(MMA/BA/3FMA) shows much better protective performance in water-resistance, and salt/freeze-thaw resistance for stone samples.