Copolymer Analysis by Gradient HPLC

As was discussed in Sect. 2, chromatographic retention may be directed by entropic and enthalpic interactions. In particular, enthalpic interactions of the 

One of the first separations of statistical copolymers using gradient HPLC was carried out by Teramachi et al. [34]. Mixtures of poly(styrene-co-methyl acrylate)s were separated by composition on silica columns through a carbon tetrachloride/methyl acetate gradient (see Fig. 11). When increasing the content of methyl acetate in the eluent, retention increased with increasing methyl acrylate content in the copolymer. This behavior fitted the normal-phase chromatographic system used. Similar separations could be achieved on other columns as well, such as polar bonded-phase columns (diol, nitrile, amino columns) [1]. 

2 Copolymer Analysis by Liquid Chromatography at the Critical Point of Adsorption 

Another more reeent approach to the chromatographic characterization of copolymers is the eoneept of invisibility , which assumes that chromatographic conditions exist under whieh heteropolymers may be separated according to the 

The application of liquid chromatography at the critical point of adsorption to block copolymers is based on the consideration that Gibbs free energy AGab of a block copolymer A Bm is the sum of the contributions of block A and block B, AGa and AGb respectively  

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