TY - JOUR
T1 - Depletion, melting and reentrant solidification in mixtures of soft and hard colloids
AU - Marzi, Daniela
AU - Capone, Barbara
AU - Marakis, John
AU - Merola, Maria Consiglia
AU - Truzzolillo, Domenico
AU - Cipelletti, Luca
AU - Moingeon, Firmin
AU - Gauthier, Mario
AU - Vlassopoulos, Dimitris
AU - Likos, Christos N.
AU - Camargo, Manuel
N1 - Publisher Copyright:
© The Royal Society of Chemistry.
PY - 2015
Y1 - 2015
N2 - We present extensive experimental and theoretical investigations on the structure, phase behavior, dynamics and rheology of model soft-hard colloidal mixtures realized with large, multiarm star polymers as the soft component and smaller, compact stars as the hard one. The number and length of the arms in star polymers control their softness, whereas the size ratio, the overall density and the composition are additional parameters varied for the mixtures. A coarse-grained theoretical strategy is employed to predict the structure of the systems as well as their ergodicity properties on the basis of mode coupling theory, for comparison with rheological measurements on the samples. We discovered that dynamically arrested star-polymer solutions recover their ergodicity upon addition of colloidal additives. At the same time the system displays demixing instability, and the binodal of the latter meets the glass line in a way that leads, upon addition of a sufficient amount of colloidal particles, to an arrested phase separation and reentrant solidification. We present evidence for a subsequent solid-to-solid transition well within the region of arrested phase separation, attributed to a hard-sphere-mixture type of glass, due to osmotic shrinkage of the stars at high colloidal particle concentrations. We systematically investigated the interplay of star functionality and size ratio with glass melting and demixing, and rationalized our findings by the depletion of the big stars due to the smaller colloids. This new depletion potential in which, contrary to the classic colloid-polymer case, the hard component depletes the soft one, has unique and novel characteristics and allows the calculation of phase diagrams for such mixtures. This work covers a broad range of soft-hard colloidal mixture compositions in which the soft component exceeds the hard one in size and provides general guidelines for controlling the properties of such complex mixtures.
AB - We present extensive experimental and theoretical investigations on the structure, phase behavior, dynamics and rheology of model soft-hard colloidal mixtures realized with large, multiarm star polymers as the soft component and smaller, compact stars as the hard one. The number and length of the arms in star polymers control their softness, whereas the size ratio, the overall density and the composition are additional parameters varied for the mixtures. A coarse-grained theoretical strategy is employed to predict the structure of the systems as well as their ergodicity properties on the basis of mode coupling theory, for comparison with rheological measurements on the samples. We discovered that dynamically arrested star-polymer solutions recover their ergodicity upon addition of colloidal additives. At the same time the system displays demixing instability, and the binodal of the latter meets the glass line in a way that leads, upon addition of a sufficient amount of colloidal particles, to an arrested phase separation and reentrant solidification. We present evidence for a subsequent solid-to-solid transition well within the region of arrested phase separation, attributed to a hard-sphere-mixture type of glass, due to osmotic shrinkage of the stars at high colloidal particle concentrations. We systematically investigated the interplay of star functionality and size ratio with glass melting and demixing, and rationalized our findings by the depletion of the big stars due to the smaller colloids. This new depletion potential in which, contrary to the classic colloid-polymer case, the hard component depletes the soft one, has unique and novel characteristics and allows the calculation of phase diagrams for such mixtures. This work covers a broad range of soft-hard colloidal mixture compositions in which the soft component exceeds the hard one in size and provides general guidelines for controlling the properties of such complex mixtures.
KW - LINEAR POLYMER MIXTURES
KW - STAR-POLYMERS
KW - PHASE-BEHAVIOR
KW - CLUSTER FORMATION
KW - SPHERE MIXTURES
KW - PARTICLES
KW - NANOCOMPOSITES
KW - SIMULATION
KW - SEPARATION
KW - SCATTERING
UR - http://www.scopus.com/inward/record.url?scp=84945376775&partnerID=8YFLogxK
U2 - 10.1039/c5sm01551k
DO - 10.1039/c5sm01551k
M3 - Article
VL - 11
SP - 8296
EP - 8312
JO - Soft Matter
JF - Soft Matter
SN - 1744-683X
IS - 42
ER -