聚醋酸乙烯酯多孔材料的制备工艺及其表征

背景:泡孔的直径及其分布的控制是制备多孔聚合物材料的难题,但目前尚无有效的解决办法.目的:采用高内相比乳液模板法,以Span80为引发剂,制备聚醋酸乙烯酯多孔材料,分析制备工艺对其泡扎直径及其分布的影响.设计,时间及地点:观察实验,于2008-12/10在泰山医学院高分子化学实验室完成.材料:醋酸乙烯酯由天津永大化学工业公司提供;二乙烯基苯、Span80由美国Aldrich公司提供;无水氯化钙、氯苯由上海第一试剂公司提供;甲苯由天津纵横兴化学工业公司提供;1,2-二氯苯由北京精益化学试剂公司提供.方法:向装有电动搅拌器和温度计的250 mL三颈烧瓶中加入连续相(醋酸乙烯酯、二乙烯基苯、致孔剂等)和乳化剂,搅拌并通过蠕动泵缓慢滴加含有过硫酸钾和CaCl2的水溶液,并控制反应温度.滴加完毕后,继续搅拌,移至60℃的水浴中继续聚合.然后将聚合好的坚硬的固体,切成1 cm厚的小圆盘状,装入Soxlet提取器中,用无水乙醇作溶剂抽提48 h.再将抽提好的崮体放入烘箱中,在50℃F干燥即可制得聚醋酸乙烯酯多孔材料.扫描电镜观察泡孔直径、窗口直径,3H-2000Ⅱ型全自动氮吸附比表面积测试仪测定多孔材料的比表面积.主要观察指标:多孔材料的比表面积、泡孔直径、窗口直径.结果:制备的聚醋酸乙烯酯多孔材料的平均泡孔直径3.3～5.2 μ m,窗口直径1.7～2.3 μ m.在反应体系中加入某些非反应性溶剂如甲苯等替代部分反应单体可制得比表面积高达720 m2/g的聚醋酸乙烯酯多孔材料.结论:采用高内相比模板法,通过控制乳液前躯体的反应条件和反应体系的组成,可以制备出泡孔直径可控的聚醋酸乙烯酯多孔材料.

Preparation technique and characterization of polyvinylacetate porous materials

BACKGROUND: How to control the diameter and distribution of void is a tough problem for the preparation of polyvinylacetate porous materials, which is lack of efficient solutions. OBJECTIVE: To prepare polyvinylacetate porous materials by using high internal phase emulsions as templates, and to study the effect of preparation technique on diameter and distribution of void. DESIGN, TIME AND SETTING: The observational experiment was performed at the Institute of Chemistry and Chemical Engineering, Taishan Medical University from March 2007 to October 2008. MATERIALS: Vinylacetate was supplied by Tianjin Yongda Chemical Industry Co., Ltd. Divinylbenzene and sorbitan monooleate (SPAN 80) were provided by Aldrich Company (USA). Anhydrous calcium chloride and chlorobenzene was obtained from Shanghai No.1 Reagent Plant. Toluene was purchased from Tianjin Zonghengxing Chemical Industry Co., Ltd. 1,2-Dichlorobenzene was offered by Beijing Jingyi Chemical Plant. METHODS: The emulsions were obtained by adding dropwise aqueous solution of CaCl2 and potassium persulfate to the continuous phase (vinylacetate, DVB and Span80) under stirring, and then polymerization was heating by water bath in constant temperature (60 ℃). The solid foams were cut into 1 cm disciform strips and extracted with propanol for 48 hours in a Soxhlet apparatus. Solid foams were dried under vacuum at 50 ℃ to obtain polyvinylacetate porous materials. The void diameter, window diameter was observed by scanning electron microscope, the specific surface area was measured by 3H-2000Ⅱ instrument. MAIN OUTCOME MEASURES: The specific surface area, void diameter and window diameter of porous materials. RESULTS: The void diameters of the polyvinylacetate porous materials were controlled 3.3-5.2 μm with window diameters of 1.7-2.3 μm. The surface areas greater than 720 m2/g could be achieved by replacing some of the monomer phase with non-polymerizable solvent, such as toluene. CONCLUSION: Polyvinylacetate porous materials with tailored void diameters can be produced via optimizing the composition and processing conditions of the emulsion precursor by high internal phase ratio template method.