The Synthesis Of Hydrophobic Modified Polyacrylamide In Supercritical CO₂

Based on the review of research on polyacrylamide and its application in domestic and abroad, a new method of synthesis of hydrophobic modification of polyacrylamide was operated under supercritical CO₂ . Modification of polyacrylamide was synthesized by using acrylamide and ester monomers fluoride (dodecafluoroheptyl methacrylate) as main materials , benzoyl peroxide (BPO) as initiator and supercritical CO₂ as reacting medium. A small amount of acetone was added as a co-solvent into supercritical CO₂ to enhance the ability to dissolved monomer, and improved the conversion rate and the molecular weight.In this thesis, physical and chemical properties and the types of polyacrylamide, synthesizing methods and application of polyacrylamide at present were introduced first. Then elementary property of the supercritical CO? and supercritical fluid were introduced.Copolymerization law of acrylamide and ester monomers fluoride (dodecafluoroheptyl methacrylate) with benzoyl peroxide (BPO) as initiator under the condition of supercritical CO₂ and supercritical CO₂ with acetone were studied. . The optimum reaction conditions were also discussed in detail. Water-soluble experiment of the product was tested to measure the hydrophobic nature. The structure of the copolymer product was illustrated by using infrared (IR) spectroscopy, and the thermal stability of the product was analyzed by employing thermal gravimetric analysis (TG).The effect of initiator concentration, monomer concentration, reaction temperature, reaction time, CO₂ pressure on the reaction conversion and impact of copolymer molecular weight were discussed which was operated under the condition of supercritical CO₂ or supercritical CO₂ with acetone on. It showed that initiator concentration, monomer concentration, reaction temperature, polymerization reaction time and CO)2 pressure had more significant impact on the conversion rate and the relatived molecular mass of product. The polymerization reaction was in accordance with the basic law of radical polymerization reaction. Based on the single factor, orthogonal polymerization experiments including initiator concentration, monomer concentration, reaction temperature and reaction time were carried on for further study which were operated under supercritical CO₂ with acetone to get the optimal reaction conditions.The results were as follows: the most effective aspect to the conversion rate of polymerization reaction was the reaction time, the most effective aspect to molecular weight of the product was the reaction temperature, Finally the optimal synthesis condition of modified polyacrylamide was confirmed: the initiator concentration was 0.06×10^-2g/mL; the monomer concentration was 4.5×10^-2g/mL; the reaction temperature was 45℃;the reaction time was 4h and the pressure of CO₂ was 15MPa. Validating experiment was operated in this condition .The conversion rate was 68.3%; the molecular weight was about 0.636 million.