Synthesis And Properties Of Fluorine-containing Polymer In Supercritical Carbon Dioxide

In this paper, the copolymer of poly(2,2,2-trifluoroethyl methacrylate-co-methacrylic acid) and poly(vinyl acetate-co-chlorotrifluoroethylene-co-maleic anhydride) were produced in supercritical carbon dioxide, and the effect of reactive conditions on the polymerization was investigated, in addition, the structures and properties of the polymers were determined. Otherwise, the poly(vinyl acetate-co-chlorotrifluoroethylene-co-maleic anhydride) powder were added into cement to modify, and the corresponding performance of modified cement was measured. The results show that the poly(2,2,2-trifluoroethyl methacrylate-co-methacrylic acid) and poly(vinyl acetate-co-chlorotrifluoroethylene-co- maleic anhydride) were white powder solid, the morphology of poly(2,2,2-trifluoroethyl methacrylate-co-methacrylic acid) changed from'granule'to'slice structure'with increasing the content of 2,2,2-trifluoroethyl methacrylate in the polymer, and the'slice structure'was 2,2,2-trifluoroethyl methacrylate-rich units. A phenomena in the polymerization had also been found, the pressure and reaction process was isochronous, when the polymerization pressure changes less, it shows the polymerization is almost over.On the certain experimental conditions, the polymerization in supercritical carbon dioxide rate equation can express as this equation: Rp∝[TFEMA]0.60[MAA]1.75[AIBN]0.81, and the apparent activation energy of polymerization in supercritical carbon dioxide was 63.72 KJ·mol-1. The activity ratio of 2,2,2-trifluoroethyl methacrylate and methacrylic acid polymerization in supercritical carbon dioxide was: rTFEMA=0.0284, rMAA=3.6056, and the activity ratio of 2,2,2-trifluoroethyl methacrylate and methacrylic acid bulk polymerization was: rTFEMA=0.0552, rMAA=1.6983. Poly(2,2,2-trifluoroethyl methacrylate-co-methacrylic acid) could self-emulsify to form latex in water, the particle size turns smaller with increasing the content of methacrylic acid in the copolymer.In this work, the surface performance of copolymers were studied, the results shown that the contract angle of solvent to polymer film turned bigger with increasing the content of fluorine-containing monomer. In addition, the hotter disposal temperature could accelerate the fluorine-containing units move towards the polymer film, as a result, the contract angle of solvent to polymer film turned bigger.Poly(vinyl acetate-co-chlorotrifluoroethylene-co-maleic anhydride) could self-emulsify to form latex, the particle size turns smaller with increasing the content of maleic anhydride. Polyol and polyamine can be used as the cross-linked reagent of poly(vinyl acetate-co-chlorotrifluoroethylene-co-maleic anhydride), the polymers could cross-linked on a certain condition.Poly(vinyl acetate-co-chlorotrifluoroethylene-co-maleic anhydride) could be used to modify cement and improved the performance of cement. After the polymer was added into cement, the hole in cement turned less and the polymer film can be formed in cement, it shows that the polymer can improve the performance of cement.