Aqueous Two-phase Copolymerization Of Acrylamide And Cationic Monomers

Polyacrylamide(PAM) is the general designation of homopolymer and copolymer of acrylamide and its derivant. PAM is a linear water soluble polymer, which is widely used in water treatment, paper making, petroleum and other industry. Cationic copolyacrylamide is widely used in abroad, but in China, the manufacturing technology and product quality are poor, which make it difficult to fulfill the need of customers. The concept of aqueous two-phase polymerization was come up in the end of 20 century and aqueous two-phase polymerization of acrylamide was studied then. But the copolymerization of acrylamide in the aqueous two-phase system was little reported, based on that, the thesis first use the aqueous two-phase copolymerization to prepared the water soluble copolymer.Aqueous two-phase polymerization is a new mode of polymerization, in which the water-soluble monomers and another water-soluble compound are dissolved to form a homogeneous aqueous solution, then polymerize to form a heterogeneous polymer dispersion aqueous solution. The system has a relatively low viscosity and high concentration, and it does not have the pollution of organic solvent. In a word, it has a broad application.The aqueous two-phase copolymerization of the cationic comonomer and acrylamide is an extension of aqueous two-phase homopolymerization, which introduces cationic comonomer and accords the need of water soluble polymer industry. It not only overcomes the problem of mixing and heat transfer, but also improves the stability of the system.Ammonium sulphate aqueous solution was selected as the dispersed medium. The phase diagrams of ammonium sulphate-PAM- system at different temperature were determined. In the PEG-PAM-H2O system, the effect of temperature, concentrations of PEG and PAM on the partition coefficient of (2-methacry loyloxyethyl) trimethyl ammonium chloride (DMC) was studied, and thermodynamics properties of PEG-PAM-H₂O system were describes with the model of Flory-Huggin.According to the morphology and droplet size and distribution of dispersed droplet,the mechanisms of the formation and stability of droplets were presented. Two facts promoted the droplets of PAM aqueous solution to disperse in the PEG aqueous solution phase, which include the steric effect and electronic repulsion effect of cationic comonomer. Compared with the homopolymerization, aqueous two-phasecopolymerization system has a higher stability.The reactivity ratios of DMC/AM and DM/AM homogeneous aqueous solution copolymerization are determined and the 95% and 99% joint confidence regions are also calculated. The conversion versus time curves and the composition of DMC-AM copolymers are compared in two copolymerization systems, a new method of calculating the copolymer composition is presented for aqueous two-phase copolymerization. The copolymer composition calculated by this method is good agreed with the experiment data.Keeping low viscosity of the polymerization system during the aqueous two-phase polymerization is an important advantage to other polymerization methods. Molecular weight and dispersion is also an important data for the performance of PAM. So the thesis studied on the change of the viscosity of the polymerization process, the effect of the concentration of dispersed medium and molar ratio on the product of aqueous two-phase copolymerization.