Effect of Chain Tilt on the Interaction between Brush-Coated Colloids

Matsen, Mark W.

doi:10.1021/ma050362x

Cited by 17 publications

(25 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, this effect has been anticipated by molecular dynamics (MD) simulations of pairwise interactions between alkanethiol-capped Au NCs 34 and self-consistent field theory calculations of overlapping spherical brushes. 38 Capping ligand structure may also be influenced by the amorphous carbon film that supports 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 With simple geometry and chain packing assumptions, OPM and OCM are appealing models for considering "hairy" sphere packings. OPM correctly predicts the dimensions of extended NC arrays.…”

Section: Resultsmentioning

confidence: 99%

Many-Body Effects in Nanocrystal Superlattices: Departure from Sphere Packing Explains Stability of Binary Phases

2015

View full text Add to dashboard Cite

This work analyzes the role of hydrocarbon ligands in the self-assembly of nanocrystal (NC) superlattices. Typical NCs, composed of an inorganic core of radius R and a layer of capping ligands with length L, can be described as soft spheres with softness parameter L/R. Using particle tracking measurements of transmission electron microscopy images, we find that close-packed NCs, like their hard-sphere counterparts, fill space at approximately 74% density independent of softness. We uncover deformability of the ligand capping layer that leads to variable effective NC size in response to the coordination environment. This effect plays an important role in the packing of particles in binary nanocrystal superlattices (BNSLs). Measurements on BNSLs composed of NCs of varying softness in several coordination geometries indicate that NCs deform to produce dense BNSLs that would otherwise be low-density arrangements if the particles remained spherical. Consequently, rationalizing the mixing of two NC species during BNSL self-assembly need not employ complex energetic interactions. We summarize our analysis in a set of packing rules. These findings contribute to a general understanding of entropic effects during crystallization of deformable objects (e.g., nanoparticles, micelles, globular proteins) that can adapt their shape to the local coordination environment.

show abstract

Section: Resultsmentioning

confidence: 99%

Many-Body Effects in Nanocrystal Superlattices: Departure from Sphere Packing Explains Stability of Binary Phases

2015

View full text Add to dashboard Cite

show abstract

“…The most accurate approach 4,23 uses the free energy per chain, f(l; R), from a single particle of radius, R, with its brush compressed to a thickness of l. The Appendix provides a simple analytical estimate for f(l; R) calculated with SST. In SCFT, f(l; R) has to be evaluated numerically, but this is nevertheless a trivial one-dimensional calculation of an isolated particle with a reflecting boundary placed at r ) R + l. Once the free energy of the uniformly compressed brush is known, the interaction energy of nonuniform compression is approximated as…”

Section: Derjaguin Approximationmentioning

confidence: 99%

“…As expected, we find that the force between the two particles is purely repulsive regardless of the particle size, brush thickness, or particle separation. We also take advantage of our full SCFT solution to examine the accuracy of the former SST approach in ref 4 and to test the reliability of the Derjaguin approximation.…”

Section: Introductionmentioning

confidence: 99%

Interaction between Polymer-Grafted Particles

Kim

Matsen

2008

Macromolecules

View full text Add to dashboard Cite

Previous self-consistent field theory (SCFT) calculations have predicted that the steric interaction between two polymer-grafted particles in good solvent can become attractive, but this conclusion has since been questioned. Here we reexamine the problem with a new numerical scheme using multiple coordinate systems, and find that the interaction remains repulsive regardless of the particle size, brush thickness, or particle separation. The erroneous attraction in the earlier calculations can be attributed to numerical inaccuracy and a subtle issue with how the chains were grafted to the particles. Using our corrected SCFT solution, we also investigate the accuracy of a previous calculation based on strong-stretching theory (SST) and the applicability of the Derjaguin approximation, where the interaction between large particles is estimated from the one-dimensional uniform compression of polymer brushes.

show abstract

“…With these sophisticated theories, the effect of chain tilting during the interaction can also be taken into account. 25 Although these models provide useful insights into the phenomenon of steric interaction, the application of these models is limited by the fact that only numerical solutions of these models are available. Lozsan et al found that a model based on the Flory−Krigbaum theory assuming uniform segment density distribution (it was called extended Vincent (EV) model by the authors) could quantitatively describe the steric interaction between two spherical particles with satisfactory accuracy, 31 which indicates that simple mathematical descriptions are available to yield sufficient approximation for estimating the steric interaction energy.…”

Section: ■ Introductionmentioning

confidence: 99%

Theoretical Investigation on the Steric Interaction in Colloidal Deposition

Lin

Wiesner

2012

Langmuir

View full text Add to dashboard Cite

A theoretical investigation was conducted upon the steric interaction between a spherical particle and a flat plate. The effects of curvature on both the segment density distribution of polymer and on the steric interaction energy between a particle and a plate were examined. It was found that the conventional approach using Derjaguin approximation may overestimate the interaction energy, especially for very small particles. Based on the results obtained from applying the Flory-Krigbaum theory with the accurate geometry change during the interaction, simple approximate expressions of exponential form were proposed for both the osmotic (mixing) and elastic contributions to the steric interaction energy for a sphere-plate interaction. The proposed model was validated against a set of experimental results from a reported study employing atomic force microscopy. Also investigated was the steric interaction between a spherical particle coated with polymer and an uncoated flat surface. It was found that the steric interaction energy from the osmotic contribution is significantly higher than that from the elastic contribution and that steric interaction is considerably weaker when the polymer exists on only one of the interacting surfaces.

show abstract

Effect of Chain Tilt on the Interaction between Brush-Coated Colloids

Cited by 17 publications

References 19 publications

Many-Body Effects in Nanocrystal Superlattices: Departure from Sphere Packing Explains Stability of Binary Phases

Many-Body Effects in Nanocrystal Superlattices: Departure from Sphere Packing Explains Stability of Binary Phases

Interaction between Polymer-Grafted Particles

Theoretical Investigation on the Steric Interaction in Colloidal Deposition

Contact Info

Product

Resources

About