Growth of Wormlike Surfactant Micelles Induced by Embedded Polymer: Role of Polymer Chain Lengthстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 10 августа 2018 г.
Аннотация:Incorporation of polymer chains into wormlike surfactant micelles, which find a large range of applications, offers the opportunity to modify their structure and properties. In this paper using spectroscopic, scattering, rheological techniques and computer simulations, we study the incorporation of poly(4-vinylpyridine) of two different molecular weights (MWs) into entangled networks of wormlike surfactant micelles of potassium oleate. Using NMR-spectroscopy we show that independently of its MW the polymer incorporates into the core-corona interface of the surfactant micelles. According to SANS data, the polymer does not alter the micelle structure or the micelle radius, but diminishes the packing density of surfactant. At the same time, rheology reveals a stark difference between the surfactant networks with embedded polymers of different MWs. Networks with higher-MW polymer possess larger viscosity and longer relaxation time, which we attribute to larger length of hybrid micelles. Moreover, we demonstrate that in an intermediate concentration range the higher-MW polymer is able to link neighboring surfactant micelles together, which has never been previously observed. However, with a further increase in polymer content the micelles become smaller due to high break susceptibility of boundaries of polymer-containing sections leading to stabilization of micellar end-caps by the embedded macromolecules. This process is more prominent in the case of shorter polymer. Our findings that an increased MW of macromolecules permits formation of longer hybrid micelles and enhances their rheological properties are of obvious importance for fundamental understanding of polymer-surfactant interactions and the development of new industrial formulations based on hybrid polymer-wormlike surfactant micelles.