Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New ID pictures of conducting polymers discover a surprise ABBA fan

18.06.2018

The first ever detailed pictures of the structure of conjugated polymers have been produced by a research team led by Professor Giovanni Costantini at the University of Warwick

  • First ever detailed pictures of conjugated polymers - which conduct electricity and are highly sought after - captured with novel visualisation technique developed by University of Warwick
  • New approach realises Richard Feynman's famous remark that it would be very easy to make an analysis of any complicated chemical substance; all one would have to do would be to look at it and see where the atoms are"
  • Polymers need alternating pattern of "A" monomer & smaller "B" monomer (ABAB), but the researchers discovered surprising gaps & defects in polymer structure - an ABBA pattern

STM image showing how the detail of thestructure of C14DPPF-F can be seen. The polymer backbones appear as bright rows and the alkyl sidechains are seen as darker rows perpendicular to the backbones.

Credit: University of Warwick


STM image showing how the detail of the structure of C14DPPF-F can be seen -- this new technique giving sub molecular resolution of the polymer backbone and the interdigitation of the alkyl sidechains. White arrows indicate gaps in the alkyl chain interdigitation.

Credit: University of Warwick

The first ever detailed pictures of the structure of conjugated polymers have been produced by a research team led by Professor Giovanni Costantini at the University of Warwick.

The ability of these polymers to conduct electricity makes them highly sought after, but until now they could also be described as extremely camera shy as there has been no easy means to determine their structure. The new technique allows researchers not only to determine it but to actually clearly see it with their own eyes.

Conjugated polymers are able to conduct electricity because they are a chain of conjugated molecules where electrons can move freely due to their overlapping electron p-orbitals. Effectively, they are excellent molecular wires. Moreover, they are akin to semiconductor materials (they have energy gaps), so they can be used for electronic (plastic electronics) and photovoltaic (organic solar cells) applications.

Modern functional polymers are often co-polymers, that is, they are made by an (ideally regular) sequence of different monomers. The order of these monomers is essential to their opto-electronic properties which can be severally damaged by errors in how the monomers actually link up in a chain to form the polymer (so called polymerisation errors occurring during the synthesis of these materials). However, detecting the nature and exact position of these errors has proved problematic with current analytical methods. Mass spectrometry does not provide a solution, as shorter polymer chains are typically more likely to be ionised and thus tend to be overrepresented in the spectra.

Costantini and co-workers have proposed and implemented a completely novel approach to overcome this fundamental analytical problem. The underlying idea is extremely simple, yet at the same time transformative: deposit the polymers onto a surface and image them by high-resolution scanning tunnelling microscopy (STM). This approach effectively realises one of the visionary predictions by Richard Feynman's in his famous 1959 speech There's Plenty of Room at the Bottom, where he said that in the future "it would be very easy to make an analysis of any complicated chemical substance; all one would have to do would be to look at it and see where the atoms are".

The atomic-scale resolution of STM is ideal for this aim but the problem remains that the chains of polymer molecules have first to be deposited intact in vacuum onto atomically clean and flat surfaces. The usual method of doing this involves heating the molecular material until it sublimes but, for molecules as large as polymers, this effectively melts the structure that should be studied. The authors have thus opted for a new method which sprays a cloud of the polymer through a series of tiny openings into a vacuum chamber, allowing a single unjumbled layer to be deposited onto a surface that is fully representative of the original polymer sample. STM of these layers produced stunningly resolved pictures, clearly revealing sub-monomer details of the conjugated polymers.

The researchers led by Professor Giovanni Costantini at the University of Warwick with colleagues from Imperial, Cambridge and Liverpool have published these results in a paper entitled "Sequencing conjugated polymers by eye" that appears in Science Advances today Friday 15th June 2018. Their high-resolution STM images of the structure of conjugated polymers are so detailed that they cannot only help with quality control and fine-tuning of polymer design, but they can even be used as something akin to an intellectual property (IP) passport photo for polymers. It is speculated that such precise and clear images could help synthetic researchers to demonstrate exactly the design they wish to legally protect by dramatically improving the information available to support an application for IP protection.

In their paper, the researchers demonstrate the power of the new technique by examining the conjugated polymer: "Poly Tetradecyl-diketopyrrolopyrrole-furan-co-furan". This is a conjugated polymer of the DPP-based family that is currently showing some of the best performances in optoelectronic devices.

This material is most effective when its polymer chains form in an alternating sequence of one large "A" monomer and a smaller "B" monomer. However, flaws can happen during the synthesis that break that ideal sequence, thereby also damaging its appealing conducting and light-harvesting properties. The speculations so far were that this mainly occurs when two of the larger "A" monomers join directly together in an BAAB sequence.

When these flaws happen, gaps or voids form in the conjugated polymer's assembly in correspondence to those errors in the chain. The University of Warwick led research team was able to use their new visualisation technique to very clearly show all of these gaps and then to zoom in further onto the polymer chains, precisely spotting each of the defective monomer sequences. On doing so, to their great surprise, they found not the expected BAAB flaws but ABBA defects.

Professor Giovanni Costantini, a physicist in the University of Warwick's Department of Chemistry said:

This new capability to image conjugated polymers with sub-monomeric spatial resolution, allow us, for the first time, to sequence a polymeric material by simply looking at it. Some of the first images we produced using this technique were so detailed that when the researchers who synthesised the polymers first saw them, their overjoyed impression reminded me of how new parents react to the first ultrasound scans of their babies.

Besides representing a significant technical breakthrough, this new technique of combining vacuum electrospray deposition with high-resolution scanning tunnelling microscopy also has the potential to revolutionise the analytical capabilities in the application-relevant field of conjugated polymers where other currently available techniques are extremely limited.

I am particularly grateful to the University of Warwick which directly funded that the purchase of the electrospray deposition equipment that was crucial to making this significant technical breakthrough.

###

Note for Editors - Full research team

The research was led by Professor Giovanni Costantini form the department of Chemistry at the University of Warwick. The other authors on the paper were Daniel A. Warr, Luís M. A. Perdigão, Harry Pinfold, and Jonathan Blohm all from the University of Warwick; David Stringer from Imperial College London; Anastasia Leventis and Hugo Bronstein from Cambridge, and Alessandro Troisi from the University of Liverpool.

Links to images:

The molecular structure of C14DPPF-F. https://warwick.ac.uk/services/communications/medialibrary/images/june2018/gio_image_1.jpg

STM image showing how the detail of the structure of C14DPPF-F can be seen this new technique giving sub molecular resolution of the polymer backbone and the interdigitation of the alkyl sidechains. White arrows indicate gaps in the alkyl chain interdigitation. https://warwick.ac.uk/services/communications/medialibrary/images/june2018/gio_image_2.jpg

STM image showing how the detail of thestructure of C14DPPF-F can be seen this new technique The polymer backbones appear as bright rows and the alkyl sidechains are seen as darker rows perpendicular to the backbones https://warwick.ac.uk/services/communications/medialibrary/images/june2018/gio_image_3.jpg

Molecular model of the polymer backbone overlaid on an image of a section of C14DPPF-F (C atoms are shown in grey, O in red, N in blue and H in white). The alkyl chains have been substituted with CH3 groups for better visualisation. An ABBA defect is visible in the centre of the image https://warwick.ac.uk/services/communications/medialibrary/images/june2018/gio_image_4.jpg

Professor Giovanni Costantini, The University of Warwick https://warwick.ac.uk/services/communications/medialibrary/images/june2018/giovanni_costantini_lab.jpg

Daniel A. Warr and Luís M. A. Perdigão The University of Warwick https://warwick.ac.uk/services/communications/medialibrary/images/june2018/dan_and_luis.jpg

For further details please contact:

Professor Giovanni Costantini
Department of Chemistry
The University of Warwick
Tel: +44 (0)24 765 24934
email: g.costantini@warwick.ac.uk

or

Luke Walton, International Press Manager
University of Warwick
Tel mobile: +44 (0) 7824 540 863
Tel Office: +44 (0) 2476 150 868
Email: L.Walton.1@warwick.ac.uk

Luke Walton | EurekAlert!

Further reports about: STM chemical substance conduct electricity electricity polymer chains vacuum

More articles from Life Sciences:

nachricht Fish recognize their prey by electric colors
13.11.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht The dawn of a new era for genebanks - molecular characterisation of an entire genebank collection
13.11.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

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 Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

The dawn of a new era for genebanks - molecular characterisation of an entire genebank collection

13.11.2018 | Life Sciences

Fish recognize their prey by electric colors

13.11.2018 | Life Sciences

Ultrasound Connects

13.11.2018 | Awards Funding

VideoLinks
Science & Research
Overview of more VideoLinks >>>