= Solution
<Gel permeation chromatography> separates by solution <hydrodynamic volume>, rather than <molar mass> alone. At equal <molar mass>, a more extended chain accesses fewer pores and elutes earlier. \b[The relatively rigid, conjugated poly(3-hexylthiophene) is the natural first-eluting candidate], compared with the more flexible chains, provided all samples are molecularly dissolved.
This is a structural prediction, not an unconditional ordering: <solvent quality>, <polymer aggregation> and column interactions affect retention, and the hydrogen-bonding <polyamide> may not dissolve adequately in tetrahydrofuran. An insoluble sample cannot be assigned an ordinary solution <gel permeation chromatography> elution time.
A differential <refractive index detector> can detect all four <polymers> when their refractive-index contrasts are nonzero. <Light scattering> with an appropriate concentration detector can additionally provide <molar mass>. A single ultraviolet detector is unsuitable as the universal detector because <polypropylene> lacks the strong chromophores present in the aromatic and conjugated products.
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