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Handbook of Size Exclusion Chromatography and Related ...

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polymer injected in the first 19 fractions. Apparently,adsorption was absent in<br />

these two separations. Agreater injection volume in toluene indicates easier<br />

partitioning <strong>of</strong> polymer to the pore, especially at low concentrations. The latter is<br />

reasonable when we consider the smaller chain dimension in the theta solvent<br />

compared with fully swollen chains in the good solvent.<br />

Adifferenceintheseparationperformance<strong>of</strong>dioxane<strong>and</strong>tolueneisevident<br />

inSEC chromatograms <strong>of</strong>the separated fractions (Fig.8).Thevalues <strong>of</strong> Mw; Mn,<br />

<strong>and</strong>Mw=Mn intheseparationintoluenearelistedinTable1forfractionsanalyzed.<br />

The molecular weights <strong>of</strong> PCL, MPCL, were converted from MPS, polystyreneequivalent<br />

MW,using theformula,MPCL ¼MPS 0:462.The latter wasobtained<br />

inSECwithamulti-anglelaserlight-scattering detector(Wyatt;DawnDSP,Santa<br />

Barbara, California) by comparing the plots <strong>of</strong> Mw as afunction <strong>of</strong> the retention<br />

volume for broad-distribution polystyrene <strong>and</strong> PCL.<br />

Thechromatogramsfortheseparationindioxanearetypical<strong>of</strong>HOPCinthe<br />

goodsolventcondition.Thetransitioninearlytolatefractionsissimilartotheone<br />

Figure 8 SEC chromatograms for some <strong>of</strong> the fractions obtained in separation <strong>of</strong><br />

PCL10K by a C8-120B column in (a) dioxane <strong>and</strong> (b) toluene. The chromatogram for the<br />

original PCL10K is shown as a dashed line.<br />

© 2004 by Marcel Dekker, Inc.

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