Präparative Mehrschritt-Trennverfahren mit entmischenden Flüssigkeiten

✍ Scribed by Kuhn, Rainer

• Publisher: Wiley (John Wiley & Sons)
• Year: 1980
• Weight: 585 KB
• Volume: 181
• Category: Article
• ISSN: 0025-116X
• DOI: 10.1002/macp.1980.021810317

✦ Synopsis

Abstract

Multi‐step fractionation methods using demixing solvents have been used to determine the chemical distribution of binary copolymers as well as block‐ and graft‐copolymers. Four variations of these multi‐step fractionation methods are described: Cumulative fractionation, successive fractionation, semicumulative fractionation, and head‐tail type of fractionation. The ability of these fractionation methods is demonstrated by investigating two‐block copolymers of styrene and butadiene which have different chemical compositions and by fractionating a chlorinated polyethylene. Using the head‐tail fractionation procedure, one obtains a middle fraction with a compositional heterogeneity of less than 2%. The results show that the chemical compositional distributions of all chemical heterogeneous copolymers can be determined by the method of fractionation with demixing solvents provided the corresponding homopolymers can be separated into different phases. This type of separation procedure has been applied to 60 different polymer systems and should be applicable to many more polymer systems.