Publication Date:
2014-12-18
Description:
Nature Materials 14, 61 (2015). doi:10.1038/nmat4109 Authors: Lang Feng, Bezia Laderman, Stefano Sacanna & Paul Chaikin In polymer–colloid mixtures, non-adsorbing polymers dispersed with much larger colloids provide a universal yet specific entropic attraction between the colloids. Such so-called depletion interaction arises from an osmotic-pressure imbalance caused by the polymers and is considered to be independent of temperature. Here we show that, for the most commonly used polymer–colloid depletion systems, the polymer undergoes a crossover from non-adsorbing to adsorbing and that, consequently, the effective colloidal interactions depend on temperature. We also find that a combination of the enthalpic (polymer bridging) and entropic (polymer exclusion) interactions, both attractive, leads to a re-entrant regime where the colloids are dispersed and form solids both on heating and on cooling. We provide a simple model to explain the observed transitions and to fill the theoretical gap at the polymer-adsorption crossover. Our findings open possibilities for colloidal self-assembly, the formation of colloidal crystals and glasses, and the behaviour of temperature-controlled viscoelastic materials.
Print ISSN:
1476-1122
Electronic ISSN:
1476-4660
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Natural Sciences in General
,
Physics
Permalink
