Entropy-driven segregation of polymer-grafted nanoparticles under confinement

Ren Zhang, Bongjoon Lee, Christopher M. Stafford, Jack F. Douglas, Andrey V. Dobrynin, Michael R. Bockstaller, Alamgir Karim

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

The modification of nanoparticles with polymer ligands has emerged as a versatile approach to control the interactions and organization of nanoparticles in polymer nanocomposite materials. Besides their technological significance, polymer-grafted nanoparticle (PGNP) dispersions have attracted interest as model systems to understand the role of entropy as a driving force for microstructure formation. For instance, densely and sparsely grafted nanoparticles show distinct dispersion and assembly behaviors within polymer matrices due to the entropy variation associated with conformational changes in brush and matrix chains. Here we demonstrate how this entropy change can be harnessed to drive PGNPs into spatially organized domain structures on submicrometer scale within topographically patterned thin films. This selective segregation of PGNPs is induced by the conformational entropy penalty arising from local perturbations of grafted and matrix chains under confinement. The efficiency of this particle segregation process within patterned mesa-trench films can be tuned by changing the relative entropic confinement effects on grafted and matrix chains. The versatility of topographic patterning, combined with the compatibility with a wide range of nanoparticle and polymeric materials, renders SCPINS (soft-confinement pattern-induced nanoparticle segregation) an attractive method for fabricating nanostructured hybrid films with potential applications in nanomaterial-based technologies.

Original languageEnglish (US)
Pages (from-to)2462-2467
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number10
DOIs
StatePublished - Mar 7 2017

Bibliographical note

Funding Information:
We thank Prof. S. K. Kumar, Prof. Rob Riggleman, Dr. C. C. Han, and Dr. J. Hwang for valuable discussions. Funding was provided by National Science Foundation Grants DMR-1411046 (to A.K.) and DMR-1410845 (to M.R.B.). Certain equipment, instruments, or materials are identified in this paper to adequately specify the experimental details. Such identification does not imply recommendation by the National Institute of Standards and Technology nor does it imply the materials are necessarily the best available for the purpose.

Keywords

  • Confinement
  • Entropy
  • Polymer thin film
  • Polymer-grafted nanoparticle
  • Topographic pattern

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