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carolhaoyu银虫 (正式写手)
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【求助】 Preparation of the PHSA-g-PMMA Comb Stabilizer
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我想合成Core-shell PMMA latex colloids, 在这期间我要用到稳定剂，找到一篇关于PHS合成的但是有的地方不太明白，请高分子的大家们给指点一下：Preparation of the PHSA-g-PMMA Comb Stabilizer In the first step, 47.9 g of recrystalized 12-hydroxystearic acid and 0.12 g of methanesulfonic acid are dissolved into 8.53 g of toluene in a 250 mL flask, which is equipped with a reflux condenser, a Dean-Stark trap, and a magnetic stirrer. The reaction mixture is refluxed at 145-150 °C under nitrogen, and toluene is used to remove the water generated from polyesterification reaction by azeotropic distillation. This reflux condition is maintained until the volume of the collected water reaches a theoretical value of 2.3 mLand the acid value of the final product is about 31.25 mg (KOH)/g (polymer) determined by titration using 0.1mMKOHin methanol so that the degree of polymerization of the polyester poly- (hydroxystearic acid) reaches about 5-6加粗部分有些疑惑，在取1克反应样品进行测量酸度时，是不是需要 把样品中的甲苯和残量水都蒸出才能用氢氧化钾滴定呀？还是直接取1克混合物进行滴定？ Finally, about 47.72 g of poly(hydroxystearic acid)(PHSA)solution with93%nonvolatile content in toluene is collected. Thus, the teeth on the comb stabilizer are ready for the next step. In the second step, 46.76 g of xylene, 0.05 g of hydroquinone, 0.14 g of Armeen DMCD, and 5.85 g of glycidyl methacrylate are added into the same flask containing 47.7 g of PHSA solution from the previous step. The reaction mixture is refluxed again at 140 °C so that the carboxyl group on the poly(hydroxystearic acid) is converted to a methacrylate group. The reaction is ended when the acid value reaches 0.15 mg/g (nonvolatile solid) and the final reaction mixture contains 50.5% nonvolatile content, which is PHSA-GM这个反应终点我也很迷惑，反应体系一直是混合物，所谓的1克未挥发物，是不是需要取一些样品然后过滤出未挥发物进行滴定呀？ In the final step, to produce a monodisperse comb stabilizer, the monomers are fed into a reaction medium, which is a mixture of ethyl acetate and butyl acetate with a weight ratio of 2:1. A 25.6 g mixture of ethyl acetate and butyl acetate is first filled into a 250 mL flask and heated to 80 °C. Then a mixture containing 49.15 g ofPHSA-GMsolution from the last step, 44.89 g of MM and MA monomers (98:2 w/w), and 0.375 g of ADIB is precisely pumped into 这是不是需要一种特殊仪器呀？the flask over a period of 3 h. After the feeding is completed, the reaction is maintained at 82-84 °C for another 2 h. The final product is slightly brown in color. To maintain it in a flowable solution at room temperature, the comb stabilizer solution is diluted to 44.1% by adding more ethyl acetate and butyl acetate. 本人是做有机的，第一次接触到高分子化合物的合成，希望大家给以指点！！！ [ Last edited by chentp on 2008-7-28 at 22:08 ] |
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