Application Of Chitosan In CPAM Aqueous Dispersion Polymerization System And Disscussion Of Its Mechanism

A novel polymer P(CTS-AM-DMC) was prepared in tert-Butanol aqueoussolution by dispersion polymerization with acrylamide (AM) and dimethacrylatoethyltrimethyl ammonium chloride (DMC) as monomers and cation monomers, watersoluble chitosan(CTS) as stabilizer. The relationship between polymerization rate andvarying factors was investigated. The mechanism of stability of chitosan wasdiscussed.1. The effect of varying factors, i.e. the total concentration of monomers, the ratioof water and alcohol, the initiator concentration, the reaction temperature and thestabilizer concentration on the apparent vosicosity and stability of system, themonomers conversion, the molecular weight of copolymer and the average particlesize and size distribution were systematically investigated by the single factorexperiments. The optimum conditions for aqueous dispersion polymerization were asfollows:3.29%~8.32%for monomers,7.5:2.5~5.5:4.5for the ratio of water andalcohol,0.00673%~0.01681%for initiator concentration,55~60℃for the reactiontemperature,0.84%~1.67%for stabilizer concentration.2. The structure of the copolymer was charactered by infrared spectroscope(FT-IR) and proton nuclear magnetic resonance spectrum (1H-NMR). Based on theresults of infrared spectroscope, it was found that the asymmetrical stretchingvibrations of–OH groups of CTS was at3440cm-1, which was overlapped by theasymmetrical stretching vibrations of–NH2. The weak peak of–OH group from CTSwas found at3.61ppm by the analysis of the proton nuclear magnetic resonancespectrum. As the experiment results, chitosan was involved in the polymerization of AM and DMC by using chitosan as stabilizer in aqueous dispersion polymerization.3. The kinetic study of the polymerization of AM and DMC in aqueous dispersionpolymerization system was carried out by using bromating method. The effect of themonomers concentration, the initiator concentration, the ratio of water and alcohol, thereaction temperature and the stabilizer concentration on conversion-time curve weresystematically investigated. According to the results of experiments, the polymer-izationration rate equation could be represented by RP∝[M]0.1[W/A]0.3[CTS]-0.45[I]0.39.And the overall activation energy of the system was53.40kJ/mol according to theArrhenius equation.4. Based on the study of the mechanism of CTS grafting reaction, the mechanismof CTS grafting reaction with AM and DMC was explored by using V-50as initiator.As the result shown, the grafting reaction of CTS was mainly occurred in the positionof–NH2. CTS radicals could be produced through the chain initiation reaction. And thegrafting copolymerization of CTS with vinyl monomers in the system would beoccurred.