Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Hard Shell – Soft Core

Abstract:
Polymeric microspheres have a shell whose density is dependent on the temperature

Hard Shell – Soft Core

Posted on March 01, 2006

Nanoparticles whose outer shells and inner cores are made of different materials are useful for many industrial and biomedical applications. In order for nanoparticles to be used as sensors or for the controlled release of substances held within their shell, for example, an important requirement must be met: the shell must be more dense than the core to form a barrier for the external medium.

W. Richtering and I. Berndt in Aachen, in collaboration with J.S. Pedersen in Århus, Denmark, have now found an elegant solution to this problem. In a two-step process, they synthesized polymeric microspheres with a core made of poly-N-isopropylacrylamide and a shell of poly-N-isopropylmethacrylamide. Both polymers are known for a particular characteristic: they swell in water, forming microgels. Because of the different polymer building blocks used in the shell and core, these differ in the absorption of water.

At 70 °C, the temperature at which the microspheres are synthesized, both polymers are densely packed. They cannot take up much water and thus no substances dissolved in the water either. When they are cooled to 25 °C, the core and shell have the highest water content and the lowest density. Dissolved molecules can pass through the shell into the core, where they disperse. Things get especially interesting when the temperature is raised to 39 °C: at this temperature, only the swelling properties of the shell are changed. It expels water, shrinks together, and becomes denser than the core. Substances dissolved in the core can no longer pass through the shell and are now locked inside. Aside from their sensitivity to temperature, polymeric microgels with core–shell architectures have another advantage too. Selection of the basic components and the reaction conditions also allow other properties of the polymers to be controlled. In addition, the synthesis of particles with multiple shells is also a possibility; these could separate different reaction chambers within the particle. The possible applications are many and varied.

####


Author: Walter Richtering, RWTH Aachen (Germany), www.ipc.rwth-aachen.de/richtering/index.html

Title: Temperature-Sensitive Core–Shell Microgel Particles with Dense Shell

Angewandte Chemie International Edition, 2006, 45, 1737, doi: 10.1002/anie.200503888

Contact:
Editorial office:
angewandte@wiley-vch.de

or David Greenberg (US)
dgreenbe@wiley.com

or Julia Lampam (UK)
jlampam@wiley.co.uk

Copyright © Angewandte Chemie

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

Sensors

Visible Light-Sensitive Photocatalysts Used for Purification of Contaminated Water in Iran June 30th, 2015

Graphene breakthrough as Bosch creates magnetic sensor 100 times more sensitive than silicon equivalent June 28th, 2015

The peaks and valleys of silicon: Team of USC Viterbi School of Engineering Researchers introduce new layered semiconducting materials as silicon alternative June 27th, 2015

Green Chemistry Methods Used in Iran to Produce Zinc Oxide Nanoparticles June 27th, 2015

Materials/Metamaterials

BASF and Fraunhofer IPMS-CNT jointly develop electronic materials June 30th, 2015

Green Chemistry Methods Used in Iran to Produce Zinc Oxide Nanoparticles June 27th, 2015

Spain nanotechnology featured at NANO KOREA 2015 June 26th, 2015

Dais Analytic Unveils New Version of Aqualyte Membrane Technology: Updates to the Basis of the Company's Industry-Changing Nanotechnology Designed to Strengthen Position in Global Air, Energy, and Water Markets June 26th, 2015

Announcements

BASF and Fraunhofer IPMS-CNT jointly develop electronic materials June 30th, 2015

Graphene flexes its electronic muscles: Rice-led researchers calculate electrical properties of carbon cones, other shapes June 30th, 2015

Researchers from the UCA, key players in a pioneering study that may explain the origin of several digestive diseases June 30th, 2015

Oxford Instruments’ TritonXL Cryofree dilution refrigerator selected for the Oxford NQIT Quantum Technology Hub project June 30th, 2015

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