Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > NC State Engineers Discover Nanoparticles Can Break On Through

Abstract:
In a finding that could speed the use of sensors or barcodes at the nanoscale, North Carolina State University engineers have shown that certain types of tiny organic particles, when heated to the proper temperature, bob to the surface of a layer of a thin polymer film and then can reversibly recede below the surface when heated a second time.

NC State Engineers Discover Nanoparticles Can Break On Through

Raleigh, NC | Posted on September 16th, 2008

Selectively bringing a number of particles to a surface and then sinking them back below it results in controllable surface patterns. According to NC State researchers involved in the project, patterning surfaces is one of the holy grails of current nanotechnology research, and is difficult to do with certain particles. They add that the finding could result in tiny reusable bar codes, or in small fluorescent features that turn off when they sense too much heat or the presence of a certain chemical.

Dr. Jan Genzer, professor of chemical and biomolecular engineering, and Dr. Richard Spontak, professor of chemical and biomolecular engineering and materials science and engineering, published their finding along with graduate students Arif Gozen and Bin Wei in the journal Nano Letters. They worked with engineers who designed the unique particles at the University of Melbourne in Australia.

The researchers used a special type of organic nanoparticle called a core-shell microgel in which the core of a cross-linked, or networked, polymer is surrounded by a shell of a different polymer.

"Most polymers are chain-like macromolecules that are like very long, cooked spaghetti noodles, but these special core-shell particles are shaped more like squash balls of one polymer with a fuzzy surface of a different polymer," Spontak says.

Heating these approximately 30-nanometer particles - which are hundreds of times smaller than a human hair - allows them to break through a polymer/polymer interface like a submarine coming to the surface of water. Reheating the particles at a polymer surface sinks them back below the surface.

"This technique allows us to place the particles right where we want them - on the surface of a thin film," Genzer says. "It can be used to create a reusable bar code, for instance, or other functional polymer surfaces."

- kulikowski -

Note to editors: The abstract of the paper follows.

"Autophobicity-Driven Surface Segregation and Patterning of Core-Shell Microgel Nanoparticles"

Authors: Bin Wei, Arif O. Gozen, Richard J. Spontak and Jan Genzer, North Carolina State University; Paul A. Gurr, Anton Blencowe, David H. Solomon and Greg G. Qiao, University of Melbourne

Published: Online Aug. 8, 2008, in Nano Letters

Abstract: Core-shell microgel (CSMG) nanoparticles, also referred to as core-cross-linked star (CCS) polymers, can be envisaged as permanently cross-linked block copolymer micelles and, as such, afford novel opportunities for chemical functionalization, templating, and encapsulation. In this study, we explore the behavior of CSMG nanoparticles comprising a poly(methyl methacrylate) (PMMA) shell in molten PMMA thin films. Because of the autophobicity between the densely packed, short PMMA arms of the CSMG shell and the long PMMA chains in the matrix, the nanoparticles migrate to the film surface. They cannot, however, break through the surface because of the inherently high surface energy of PMMA. Similar thermal treatment of CSMG-containing PMMA thin films with a polystyrene (PS) capping layer replaces surface energy at the PMMA/air interface by interfacial energy at the PMMA/PS interface, which reduces the energy barrier by an order of magnitude, thereby permitting the nanoparticles to emerge out of the PMMA bulk. This nanoscale process is reversible and can be captured at intermediate degrees of completion. Moreover, it is fundamentally general and can be exploited as an alternative means by which to reversibly pattern or functionalize polymer surfaces for applications requiring responsive nanolithography.

####

For more information, please click here

Contacts:
Dr. Jan Genzer
(919) 515-2069


Dr. Rich Spontak
(919) 515-4200


Mick Kulikowski
News Services
(919) 515-8387

Copyright © North Carolina State University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Switching to spintronics: Berkeley Lab reports on electric field switching of ferromagnetism at room temp December 17th, 2014

ORNL microscopy pencils patterns in polymers at the nanoscale December 17th, 2014

Unraveling the light of fireflies December 17th, 2014

First Home-Made Edible Herbal Nanodrug Presented to Pharmacies across Iran December 17th, 2014

Sensors

Promising new method for rapidly screening cancer drugs: UMass Amherst researchers invent fast, accurate new nanoparticle-based sensor system December 15th, 2014

Graphene Applied in Production of Recyclable Electrodes December 13th, 2014

Detecting gases wirelessly and cheaply: New sensor can transmit information on hazardous chemicals or food spoilage to a smartphone December 8th, 2014

Nanosensor to Detect Naproxen Drug Produced in Iran December 6th, 2014

Discoveries

Switching to spintronics: Berkeley Lab reports on electric field switching of ferromagnetism at room temp December 17th, 2014

ORNL microscopy pencils patterns in polymers at the nanoscale December 17th, 2014

Unraveling the light of fireflies December 17th, 2014

Fraud-proof credit card possible because of quantum physics December 16th, 2014

Announcements

Switching to spintronics: Berkeley Lab reports on electric field switching of ferromagnetism at room temp December 17th, 2014

ORNL microscopy pencils patterns in polymers at the nanoscale December 17th, 2014

Unraveling the light of fireflies December 17th, 2014

First Home-Made Edible Herbal Nanodrug Presented to Pharmacies across Iran December 17th, 2014

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE