Synthesis Of Eco-friendly Fluorinated Acrylate Copolymer And Its Application In Stone Protection

Stone materials are prone to suffering from serious"diseases" due to intake of liquid like water and oil stain, which greatly degrade their original value. Silanes are commonly used as stone protective agent, it could penetrate into the micro-pores of stone and adsorbed onto the pore surface so that it could render the substrate great water repellent property. However silane-type protective agent is vulnerable to oil stain, this obvious drawback has restricted its use and risen demand for alternative material. Fluorine containing polymer is well-known for both water and oil repellent property and superior weathering ability, but the interaction with stone is so weak that the protective effect may not be durable. So the key issue of this research is to combine the advantage of both silanes and fluorine containing polymer to prepare an eco-friendly and high-efficient stone protective agent through molecular design and engineering optimization.We started this research with synthesis of the eco-friendly short-chain fluorinated acrylate (C4SA,C6SA in short) by continuously aminating/alcoholizing/esterifing the commercially available sulphonyl fluoride. And then this fluorinated monomer was copolymerized with 3-methacryloxypropyltrimethoxysilane(KH-570) and stearyl acrylate(SA). The monomer conversion and copolymer solubility were optimized by adjusting the reaction parameter and changing solvent type. The structures were determined by FT-IR/1H-NMR/GPC. Moreover, the surface property and stone protective effect of these acquired copolymers were intensively tested and discussed.The main conclusions are as followed. Sulphonyl fluoride could be converted into fluorinated acrylate monomer by the three-step reaction. The combined yield is around 70%. During the preparation of P(CnSA/SA/KH-570), the final conversion could be up to 97%by adjusting temperature, reaction time, initiator dosage and fed-in method. Strong correlation was found between the solubility of copolymer and solvent polarity. Molecular weight of the copolymer could be adjusted within certain range by using a chain transfer agent. The resulted copolymer has very low surface energy and great ability of W/O repellency, which was strengthened along the increase of fluorine content. The synthesized copolymer solution could penetrate into common types of decorative stone material and render them good oil-stain resistant property, the copolymer film is fairly stable at acid/ase environment. Introduction of KH-570 could further enhance the adhesion to the substrate so as to improve the water/acid/base resistant property.