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Preparation and characterization of cationic polyacrylamide in the alcohol-water media

Author: LiLingLu
Tutor: ZhangDeWen；WangZuoXin
School: Changchun University of
Course: Organic Chemistry
Keywords: Dispersion copolymenzation Cationic-Polyacrylamide temperature-sensitive
CLC: O633.22
Type: Master's thesis
Year: 2010
Downloads: 59
Quote: 2
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Abstract


Acrylamide polymers are one of very important water soluble polymer. Due to their excellent advantages, these polymers have been widely utilized as wastewater treatment flocculants in many areas, such as, petroleum industry, paper making, coal preparation, textile industry, domestic sewage and so on. In this paper, cationic polyacrylamide microspheres are successfully synthesized by dispersion polymerization in ethanol-water mixture. This special precipitation polymerization firstly requires that monomers, stabilizer and initiator dissolve well in solvent and form uniform phase. With the process of reaction, the polymer chain gradually increases to its critical length, resulting in the occurrence of precipitation. Meanwhile, stabilizer will adsorb on the surface of the precipitated particles to protect them from aggregation. Consequently, polymer particles are well suspended in the solvent and form dispersion. The prepared cationic polyacrylamide from ethanol-water mixture has high charge density, large molecular weight and fast dissolving rates. Currently, most researches are concentrating on how to enlarge the molecular weight of polymer and increase the percentage amount of monomers. However, there are very few reports regarding on obvious temperature-sensitivity from polymer suspensionHere cationic-polyacrylamide dispersions are prepared by dispersion polymerization in ethanol-water mixture using acrylamide (AM) and 2-methylacryloylxyethyl trimethyl ammonium chloride (DMC) as monomers,2,2-azobis(2-methylpropionconidine) dihydrochloride (V50) as initiator and poly(acryloylxyethyltrimethyl ammonium chloride) (PDAC) as stabilizer. Systematic investigations are to estimate the effect of several reaction factors on the final product, such as, the amount and composite of monomers, the concentration of stabilizer and initiator, reaction temperature and the ratio of ethanol/water. The morphology and particle size of polymer microspheres have been characterized by optical microscopy, TEM and laser particle analyzer respectively. Rotational Viscometer is employed to measure the intrinsic viscosity of copolymer dispersion. The conversion rate of each monomer is obtained through bromination titration method. The molecular weight is achieved by Ubbelohde viscometer. Finally, we utilize FTIR and 1H NMR to analyze the structure of copolymer.The mechanism of dispersion polymerization of soluble monomers in ethanol-water mixture has been explored preliminarily. Experimental results demonstrate that the formation process of dispersion is also the occurrence of polymer phase separation. All reaction factors which can affect the separation and particles’stability during the process of polymerization also influence the particles’size and morphology. The stability of suspension is quite dependent upon steric hindrance and electrostatic interactions from the stabilizer adsorbed on the polymer surface.Evident temperature of sensitivity has been observed from polymer suspension synthesized in ethanol-water media. Experimental results show that the transformation of copolymer’s appearance with temperature is reversible. When the temperature cool down from 50℃to 5℃, the color of copolymer dispersion was alternated from transparent to milky white; While the temperature increase to 50℃again, the suspension also becomes transparent. In order to further study the nature of temperature sensitivity, we use variable-temperature UV spectrometer to identify it. Experimental results indicated that the swelling degree of microsphere is low in low temperature due to the diminution of particles’ diameter, ultimately resulting in low transmittance rate and milky white; while in higher temperature, both the degree and the rate of suspension microspheres increase and finally become completely transparent near 50℃

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CLC: > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Miscellaneous Chain Polymers > Nitrogen-containing polymer chain > Polyamide
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