Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Polymer chemistry: A pinch of copper proves invaluable

22.11.2012
A novel approach produces dual-function molecules that enhance a widely used chemical reaction while reducing harmful by-products

Production of biocompatible and super-absorbent materials may become easier, thanks to Anbanandam Parthiban and co-workers at the A*STAR Institute of Chemical and Engineering Sciences.


Acrylic acid-based polymers and co-polymers (pictured) can now be synthesized using free radical chemistry, thanks to new ligand–initiator type molecules.



Copyright : 2012 A*STAR Institute of Chemical and Engineering Sciences

Using a modification to the high-precision technique known as atom transfer radical polymerization (ATRP), which links molecules into long chains, the researchers have developed new compounds that can directly polymerize acidic vinyl monomers, such as acrylic acid. Acrylic acid polymers are water-absorbing materials widely used in diapers and as emulsifying agents for pharmaceuticals and cosmetics.

Previous attempts to use ATRP with polar vinyl monomers, including acrylic acid, were unsuccessful, a failure that some chemists attributed to catalyst ‘poisoning’ by carboxylic acids. Parthiban and his team’s compounds resolve this problem by binding to the catalyst while simultaneously initiating the radical polymerization process. This process prevents poisoning and dramatically reduces metallic waste.

Despite ATRP’s inability to directly produce acrylic acid polymers, it is used in laboratories worldwide: it allows researchers to assemble complex polymers in a step-by-step fashion that gives enormous control over product architectures. The key is using a catalyst that can readily switch between two oxidation states, such as a copper salt, explains Parthiban. The copper catalyst first interacts with an ATRP initiator molecule to activate organic free radicals and an oxidized metal complex. The free radicals then quickly polymerize target monomers, while the metal complex undergoes equilibrium with a dormant, lower oxidation state. With appropriate reaction conditions, chemists can then restart polymerization with new monomers.

Parthiban and co-workers addressed ATRP’s limitation by developing ‘unimolecular ligand–initiator systems’ (ULIS), a series of branched molecules containing multiple binding sites for copper atoms, as well as halogens for activating free radical species. In this approach, the ULIS molecules become part of the polymer chain during the active–dormant cycles instead of remaining isolated. The researchers envisaged that this interconnection would suppress the acidic side-reactions that lead to catalyst poisoning.

Experiments by the researchers proved their theories correct: they could efficiently polymerize acrylic acid and other vinyl monomers using ULIS-promoted ATRP (see image). Surprisingly, they found that these reactions could be achieved using less than 100 parts-per-million concentrations of copper catalyst, a quantity comparable to residues left in conventional ATRP purified polymers.

Parthiban notes that although the ULIS ligands are part of the polymer chain and might be expected to produce high amounts of metal waste, the homogenous nature of intramolecular-based free radical polymerization allows less metal to be used — an important consequence for sustainable chemistry efforts.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Chemical and Engineering Sciences

Journal information

Jana, S., Parthiban, A. & Choo, F. M. Unimolecular ligand–initiator dual functional systems (ULIS) for low copper ATRP of vinyl monomers including acrylic/methacrylic acids. Chemical Communications 48, 4256–4258 (2012).

A*STAR Research | Research asia research news
Further information:
http://www.a-star.edu.sg
http://www.researchsea.com

More articles from Life Sciences:

nachricht Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care

nachricht Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>