Featured Research

from universities, journals, and other organizations

In A Show Of Entropy's Benefits, Scientists Find "Fuzzy" Molecules Can Assemble Precisely Into Distinct Lattices

Date:
October 26, 2001
Source:
University Of Pennsylvania
Summary:
Physicists at the University of Pennsylvania have determined that adding a "fuzz" of chemical chains to colloidal molecules can lead them to form a predictable array of lattices. The entropy-driven phenomenon represents a way in which the power of entropy might be harnessed by scientists for constructive purposes.

PHILADELPHIA – Physicists at the University of Pennsylvania have determined that adding a "fuzz" of chemical chains to colloidal molecules can lead them to form a predictable array of lattices. The entropy-driven phenomenon represents a way in which the power of entropy might be harnessed by scientists for constructive purposes.

Related Articles


The finding, in which researchers led by Penn physicist Randall D. Kamien examined the effects of a halo of polymer limbs on otherwise spherical molecules suspended in liquid, is the cover story in today’s issue of the Journal of Physical Chemistry B.

Kamien’s work adds new evidence that entropy is far richer than the gloomy drive toward universal disorder it was once thought to be and suggests it could become a player in the world of self-assembling molecules. Entropy’s knack for driving fuzzy molecules into distinct lattices offers scientists the promise of new materials designed rationally rather than through trial and error.

"Predicting the symmetry of the lattice formed by an organic compound is one of the oldest dreams of synthetic chemists," said Kamien, an associate professor of physics and astronomy at Penn. "By providing an empirical connection between molecular structure and macroscopic organization, our result will allow chemists to design new materials from the top down."

Kamien’s theoretical work focused on colloids, which feature particles suspended in liquid. Colloids are all around us, from milk to microreactors, from pie filling to paint. Crystals formed from colloids form the basis for a new class of functional materials for use in optical switches, chemical microreactors and molecular sieves; the new finding suggests the possibility of creating "designer molecules" to speed this process along.

"Because both the size of the colloidal particles and interparticle interactions are tunable," Kamien said, "this provides the basis for the manufacture of ordered structures with desired lattice spacings as well as mechanical, thermal and electrical properties."

Ever since Sir Walter Raleigh pondered the most efficient means of stacking cannonballs some 400 years ago, scientists have suspected that free energy, and therefore entropy, is maximized by packing particles as tightly as possible. Only in 1998 was it shown that what’s called a face-centered cubic lattice maximizes the entropy of an array of perfect spheres – but the mathematical mystery of the myriad lattices formed by certain fuzzy molecules remained. Kamien’s work solves that puzzle, showing that things become more complicated when a little fuzz enters the picture.

"The old view was that the densest packing wins," Kamien said. "Our work shows it’s not that simple, especially as molecules grow less dense."

The molecules in the colloids Kamien studied were characterized by a relatively dense core surrounded by a corona of hundreds of spindly chemical arms. When virtually none of the fuzz was present, the particles did indeed organize themselves into a face-centered cubic array.

But as the fuzz grows in length, to the point that the molecules were almost all fluff with a very small core, they would form different arrays of lattices that could be mapped with precise phase diagrams. At stages where the fuzz was of an intermediate length, Kamien’s theoretical work predicts a mixture of face-centered cubic and other lattices corresponding to the length of the fuzz, a prediction consistent with experimental findings by Penn chemist Virgil Percec and others.

Kamien’s co-author on the Journal of Physical Chemistry B paper is Primoz Ziherl, on leave from the Institut Jozef Stefan in Ljubljana, Slovenia. Kamien and Ziherl’s work was supported by the National Science Foundation, the American Chemical Society’s Petroleum Research Fund, the Alfred P. Sloan Foundation and Penn alumnus Larry Bernstein.


Story Source:

The above story is based on materials provided by University Of Pennsylvania. Note: Materials may be edited for content and length.


Cite This Page:

University Of Pennsylvania. "In A Show Of Entropy's Benefits, Scientists Find "Fuzzy" Molecules Can Assemble Precisely Into Distinct Lattices." ScienceDaily. ScienceDaily, 26 October 2001. <www.sciencedaily.com/releases/2001/10/011026075321.htm>.
University Of Pennsylvania. (2001, October 26). In A Show Of Entropy's Benefits, Scientists Find "Fuzzy" Molecules Can Assemble Precisely Into Distinct Lattices. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2001/10/011026075321.htm
University Of Pennsylvania. "In A Show Of Entropy's Benefits, Scientists Find "Fuzzy" Molecules Can Assemble Precisely Into Distinct Lattices." ScienceDaily. www.sciencedaily.com/releases/2001/10/011026075321.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Today's Prostheses Are More Capable Than Ever

Today's Prostheses Are More Capable Than Ever

Newsy (Nov. 26, 2014) Advances in prosthetics are making replacement body parts stronger and more lifelike than they’ve ever been. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins