Theory of chromatographic separation of linear and star-shaped binary block-copolymers
Equations for the distribution coefficient of heteroarm stars are derived by using a model of an ideal chain in a slit-like pore; these equations together with those previously reported for linear block-copolymers are applied to describe chromatography of such copolymers. According to the theory, th...
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Veröffentlicht in: | Journal of Chromatography A 2005-02, Vol.1064 (2), p.169-181 |
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Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Equations for the distribution coefficient of heteroarm stars are derived by using a model of an ideal chain in a slit-like pore; these equations together with those previously reported for linear block-copolymers are applied to describe chromatography of such copolymers. According to the theory, the retention generally depends on molar mass, composition, and architecture (microstructure and topology) of copolymers, on pore size and on adsorption interaction of chain units
A and
B. Three special modes of chromatography are studied in detail. (i) If interactions for
A and
B are close to the critical point of adsorption (CPA), the retention practically does not depend on architecture, and high molar mass copolymers can be separated by composition. (ii) At SEC condition for
B and strong adsorption for
A, copolymers in principle can be separated by architecture; better separation is expected in wide pores. Retention of linear block-copolymers decreases with increasing of the number of blocks; for heteroarm stars the theory predicts retention decreasing as:
AB
>
StarAAB
>
StarABB;
StarAAAB
>
StarABBB
>
StarAABB;
StarAAAAB
>
StarABBBB
>
StarAAABB
>
StarAABBB. (iii) At the CPA for
B copolymers
AB,
BAB and heteroarm stars regardless molar mass of
B,
M
B
, can be separated by
M
A
. The same is true for
ABA and
ABAB…
A in narrow pores. While the retention of
AB,
BAB,
Star AB…
B and
Star AAB…
B is the same, copolymers
AB,
ABA and linear multiblock-copolymers can be separated, as well as symmetric and very asymmetric triblock-copolymers
ABA. |
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ISSN: | 0021-9673 |
DOI: | 10.1016/j.chroma.2004.12.051 |