ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
In the preceding papers of this series, it has been shown theoretically and experimentally how the Flory–Huggins interaction parameter χ and the Huggins coefficient kH for polymers differing in molecular weight are built up from the contributions of inter- and intramolecular contacts between polymer segments. In the present work, new experimental material concerning solutions of well-fractionated polyisobutene (PIB) and polystyrene (PS) is presented which, for the first time, includes worse than theta conditions. Its evaluation corroborates the above concept and reveals two features not observed so far. As the solvent quality becomes very unfavorable, the parameters measuring the intermolecular contacts between segments increase as one would expect from the data obtained for good solvent conditions. In contrast to that, the intramolecular parameters no longer decrease smoothly below theta conditions, but show a drastic reduction. This behavior is attributed to coil-collapse phenomena. The second feature concerns the following observation: If the inter- and intramolecular parameters are plotted as a function of the Kuhn–Mark–Houwink exponent, differences in the behavior of PIB and PS become noticeable under certain conditions. These observations are explained by the influence of the particular architecture of the polymer chain.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.453491
Permalink