Preparation Of High Molecular Weight Poly (Ethylene Oxide)

Poly(ethylene oxide)(PEO) is a kind of water-soluble polymer, which can be used as conditioner, water retention agent, thickening agent, dispersant, etc. High molecular weight PEO plays distinctive role in daily chemicals formulation. In addition, PEO has very good water solubility, low toxicity, and good compatibility with other materials. Because of these advantages, high molecular weight PEO has been using more and more in excellent personal care products.High molecular weight poly(ethylene oxide) is difficult to produce, and its preparation technology is seldom reported. This thesis made systematic study on preparation technology of poly(ethylene oxide). We prepared PEO with molecular weight from105 to 106 by aluminium alkyl and acetylacetone complex catalyst. The reaction conditions were also studied, and the products were characterization by gel-permeation chromatography.Firstly, the method of catalyst preparation and the ratio of alkyl aluminum and acetylacetone in the catalyst were studied. The results show that the appearance, color and yield of PEO prepared by present catalyst were better, and the molecular weight was higher. The proper ratio of alkyl aluminum and acetylacetone in the catalyst was 1 to2 (mole ratio).Secondly, the preparation of PEO by solution polymerization was studied. The influence of amount of catalyst, solvent, reaction temperature, and reaction time on the reaction were studied. The suitable reaction conditions in toluene solution were obtained:the amount of catalyst 0.04～0.10ml/g ethylene oxide. the amount of solvent 2～3ml/g ethylene oxide, reaction temperature 10℃, reaction time 12-14h. The molecular weight of PEO prepared in toluene solution is close to 670,000 with narrow distribution, and the yield of PEO can reach 60.1%.Thirdly. the preparation of PEO by precipitation polymerization was studied. The dispersant and toluene-heptane mixed solvent were used to enhance the dispersion of the systerm. thereby the molecular weight and yield increased. The influence of the amount of dispersant. the ratio of mixed solvents. the amount of solvent. the amount of catalyst, reaction time on the reaction were studied. The suitable reaction conditions in toluene-heptane mixed solvent were obtained:the amount of dispersant 0.01～0.02g/g ethylene oxide, the volume ratio of toluene:heptane 3:7, the amount of catalyst 0.10～0.15ml/g ethylene oxide, the amount of solvent 2～3ml/g ethylene oxide, reaction temperature 10℃, reaction time 10-12h. The molecular weight of PEO prepared in toluene-heptane mixed solvent in polymerization bottle can reach 870,000 with narrow distribution, and the yield of PEO can reach 66.7%.Lastly, we conducted enlarge experiments in 1L reactor. We studied further on the effects of temperature on the reaction, and studied the effects of the water weight content of the solvent. We determined the amount of catalyst, the amount of solvent and reaction time. The suitable reaction conditions in 1L reactor were obtained:the amount of dispersant 0.01～0.02g/g ethylene oxide, the volume ratio of toluene:heptane 3:7, the amount of catalyst 0.05～0.10ml/g ethylene oxide, the amount of solvent 2～3ml/g ethylene oxide, reaction temperature 40～50℃, reaction time 8～10h, the water weight content of the solvent less than 10×10-6. The molecular weight of PEO prepared in 1L kettle can reach 1,100,000 with narrow distribution, and the yield of PEO can reach 70%.