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Title: Entropy-induced separation of star polymers in porous media

We present a quantitative picture of the separation of star polymers in a solution where part of the volume is influenced by a porous medium. To this end, we study the impact of long-range-correlated quenched disorder on the entropy and scaling properties of f-arm star polymers in a good solvent. We assume that the disorder is correlated on the polymer length scale with a power-law decay of the pair correlation function g(r){approx}r{sup -a}. Applying the field-theoretical renormalization group approach we show in a double expansion in {epsilon}=4-d and {delta}=4-a that there is a range of correlation strengths {delta} for which the disorder changes the scaling behavior of star polymers. In a second approach we calculate for fixed space dimension d=3 and different values of the correlation parameter a the corresponding scaling exponents {gamma}{sub f} that govern entropic effects. We find that {gamma}{sub f}-1, the deviation of {gamma}{sub f} from its mean field value is amplified by the disorder once we increase {delta} beyond a threshold. The consequences for a solution of diluted chain and star polymers of equal molecular weight inside a porous medium are that star polymers exert a higher osmotic pressure than chain polymers and in general highermore » branched star polymers are expelled more strongly from the correlated porous medium. Surprisingly, polymer chains will prefer a stronger correlated medium to a less or uncorrelated medium of the same density while the opposite is the case for star polymers.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [5] ;  [6]
  1. Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 79011 Lviv (Ukraine)
  2. (Germany)
  3. Theoretische Polymerphysik, Universitaet Freiburg, D-79104 Freiburg (Germany)
  4. (Poland)
  5. (Austria)
  6. (Ukraine)
Publication Date:
OSTI Identifier:
21072297
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; Journal Volume: 74; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevE.74.031801; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CORRELATION FUNCTIONS; CORRELATIONS; DENSITY; ENTROPY; LENGTH; MEAN-FIELD THEORY; MOLECULAR WEIGHT; POLYMERS; POROUS MATERIALS; RENORMALIZATION; SOLUTIONS; SOLVENTS