Continuous polymer fractionation

Highly functionalized TMSC was exploited for the continuous polymer fractionation [105]. Because of their stiff backbone with flexible side chains (so-called hair rod molecules) ultrathin films by Langmuir-Blodgett (LB) technique could be formed [106] yielding cellulose films after regeneration with HCl gas [107, 108]. 

Stoehr T, Petzold K, Wolf B.A., Klemm D., Continuous polymer fractionation of polysaccharides using highly substituted trimethylsUylcellulose, Macramo/. Chem. Phys., 199, 1998,1895-1900. 

Continuous polymer fractionation (CPF) is a liquid-liquid extraction technique developed to fractionate large amounts of polymer (51). It was originally developed to fractionate homopolymers by molecular weight and has been apphed for polyvinyl chloride (52), polyisobutylene (53,54), polyethylene (55), and polycarbonate (56). Recently, attempts to extend CPF to copolymers have been made (57) and it was shown that, under certain operational conditions, fractionation by chemical composition could also be achieved (58). 

Within this contribution, we focus our attention on two methods, namely the Baker-Williams fractionation (BW) [40,41] and continuous polymer fractionation (CPF) [42]. The B W method leads to fractions with a very low nonuniformity and is deemed to be the most effective technique [43, 44]. CPF allows the isolation of fractions on the 100 g scale. 

The production of sufficient amounts of narrowly distributed polymer samples, which cannot by synthesized with narrow molecular weight distribution, has been too laborious, except for special cases like the investigation of dilute solutions, for which only small polymer samples are required. This situation was strongly improved by the development of a new technique. Wolf et al. [78] suggested a continuous polymer fractionation method for homopolymers that allows fractions on the 100 g scale. 

Weinmann K, Wolf BA, Ratzsch MT, Tschersich L (1992) Theory-based improvements of the CPF (continuous polymer fractionation) demonstrated for poly(carbonate). J Appl Polym Sci 45 1265-1279... 

Geerissen H, Roos J, Wolf BA (1985) Continuous fractionation and solution properties of PVC, 1. Continuous fractionation, characterization. Makromol Chem 186 735-751 Geerissen H, Schiitzeichel P, Wolf BA (1990) Large scale fractionation of polyethylene by means of the continuous polymer fractionation (CPF) method. Makromol Chem 191 659-670 Gosch Cl, Haase T, Wolf BA, Kulicke WM (2002) Molar mass distribution and size of hydroxyethyl starch fractions obtained by continuous polymer fractionation. Starch/Starke 54 375-384... 

Geerissen H, Roos J, Schiitzeichel P, Wolf BA (1987) Continuous fractionation and solution properties of PIB. I. Search for the best mixed solvent and first results of the continuous polymer fractionation. J Appl Polym Sci 34 271-285... 

Gosch Cl, Haase T, Wolf BA, Kulicke WM (2002) Molar mass distribution and size of hydroxyethyl starch fractions obtained by continuous polymer fractionation. Stareh/Starke 54 375 384... 

Two patented large-scale techniques, based on liquid-liquid phase separation, are the continuous polymer fractionation (CPF) and the continuous spin fractionation (CSF)." The experimental setup of these two techniques will be presented in the next two sections (sections 2.04.2.1 and 2.04.2.2), which are followed by the description of two chromatographic methods, namely, the Baker-Williams fractionation (section 2.04.2.3) and the phase distribution chromatography (PDC) (section 2.04.2.4). 

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