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【求助】請問低分子量的硅氧烷和高分子量的硅氧烷如何分離?
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我現(xiàn)在在做的東西里含有低分子量的D4和分子量為3000左右的產(chǎn)物,由于產(chǎn)物里含有雙鍵,所以蒸餾的方法基本上是不予考慮了。請問各位有什么比較好的方法分離不同分子量的硅氧烷么?最好能有相關資料,謝謝了。! 我個人在想的是過柱子或者通過冷凍結(jié)晶的方法,但是具體的做法還沒查到。。。。 |
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在文獻中看到的,“Model Networks Of End-Linked Polydimethylsiloxane Chains .1. Comparisons Between Experimental And Theoretical Values Of Elastic-Modulus And Equilibrium Degree Of Swelling” 其實雙鍵含量不是很高的話,減壓蒸餾關系不是很大的 The polymers used in this investigation were two samples of hydroxyl-terminated PDMS, hereafter designated A and B, described as having molecular weights the order of 2 x 104 and 1 xl 03 g morl , respectively. 26 Standard fractional precipitation techniquesl carried out at 25°C were used to separate these two polymers into several fractions. Toluene was chosen as the solvent and acetonitrile as the nonsolvent. (Methanol, which is widely used as the nonsolvent in polymer fractionations, cannot be used with polymer chains of this type, which have potentially reactive end-groups). Initial polymer concentrations were 1wt% in the case of sample A and 5wt% in the case of sample B. Four fractions (A-1 through A-4) were obtained from sample A, and two (B-1 and B-2) from sample B; each represented roughly 20% of the polymer from which it was obtained. [ Last edited by pengcil on 2010-12-22 at 10:33 ] |
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