Iminoboronate Polymers as Dynamically Adaptable, Photoactive Materials

Lead Research Organisation: University of Cambridge
Department Name: Chemistry

Abstract

Polymers incorporating dynamic covalent bonds form a class of "smart" materials that are able to adapt to-or can be altered in response to-applied chemical or environmental stimuli. We propose a new class of dynamic, conjugated polymers based on the reversible iminoboronate ester bonding motif. Simple AB-type monomers incorporating aldehyde, amine, and boronic acid functionalities will polymerize together with diols to produce iminoboronate ester polymers. The presence of orthogonal dynamic imine and boronate ester bonds will allow us to develop easily functionalizable, and thus tuneable, multicomponent polymer materials that possess the ability to reorganise or adapt in response to various external stimuli. By incorporating electronically distinct diols, the photophysical properties of the conjugated polyimine polymer backbone may be tuned, providing a predictable pathway for attaining desired material properties. The unique set of characteristics of this materials system - highly tuneable electronic properties, structural rigidity through dative N-B stabilisation and electrochemical stability due to non-conjugated boron functionalization - promise to make these polymers strong candidates for light-emitting devices. (Additionally, obtaining a fundamental understanding of the affinity of the iminoboronate for electronically different diols will allow us to promote consecutive changes in polymer properties through successive diol exchanges.) These materials will be investigated as fluorescent polyreceptors for specific diols and as controllably crosslinkable or decrosslinkable materials with the addition or displacement of tetrols. Development of these high-value smart materials will lay the groundwork for the next generation of multifunctional devices, such as blue-light-emitting polymers with superior efficiency and electrochemical stability to the state-of-the-art poly(fluorene) OLEDs.

Planned Impact

Beyond the academic community, the development of new polymer materials and devices in this project will have impact on industry and the general public.

Industry: A key goal of this project is the production of new polymeric luminescent materials that are capable of emitting efficiently at a tuneable wavelength. In particular, the impact of a new family of materials for blue LEDs is very considerable, in the near term for use in full colour displays in phones, tablets and TVs, and in the longer term for OLED lighting. This is directly relevant to the very strong materials chemistry industrial activities in the UK, including CDT-Sumitomo in Cambridge and Merck in Southampton. These companies have developed state-of-the-art materials sets that are now used by Asian display manufacturers. For example, the 4k-resolution 55-inch OLED TV demonstrated by Panasonic is fabricated by printing of materials sets developed by CDT-Sumitomo. This falls very directly within the scope of 'Advanced Materials', one of the UK's 'Eight Great Technologies'.
Intellectual property (IP) will be protected and exploited in accordance with the published policy of the University of Cambridge to the benefit of all individuals and institutions involved. After the protection of any relevant IP, dissemination will be through publication in top international journals and domestic and international presentations. We will make sure that relevant IP is patented, potential licensees are recognised, and that possibilities for launching spin-outs are also properly identified.

General public: Appreciation and public support for scientific progress have underpinned technological progress in the UK ever since the practice of science became professionalised in the 19th century. We are committed to maintaining our side of this dialogue through explaining to the public what we do and why. One mechanism for this is press coverage of our research programme. The Nitschke group's 2009 Science paper generated a dozen stories in newspapers, TV, and radio across more than five countries, all with a positive bent. Another mechanism is structured outreach events; JRN will present his group's research to the 2014 international 'Pint of Science' festival (http://www.pintofscience.com/).

Education: In the context of undergraduate education, one of the Nitschke group's self-assembled systems will be highlighted in the next edition of a first-year undergraduate chemistry textbook and has already been adapted for use in undergraduate practical exercises.

Publications

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Conaghan PJ (2018) Efficient Vacuum-Processed Light-Emitting Diodes Based on Carbene-Metal-Amides. in Advanced materials (Deerfield Beach, Fla.)

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Fallon KJ (2019) Exploiting Excited-State Aromaticity To Design Highly Stable Singlet Fission Materials. in Journal of the American Chemical Society

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Greenfield JL (2018) Unraveling Mechanisms of Chiral Induction in Double-Helical Metallopolymers. in Journal of the American Chemical Society

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Greenfield JL (2017) Self-Assembly of Conjugated Metallopolymers with Tunable Length and Controlled Regiochemistry. in Angewandte Chemie (International ed. in English)

 
Description New conjugated polymers have been prepared - several high-impact papers have been published, with more on the way. These polymers emit white light, and applications as conductive materials ('molecular wires') are being explored. We have also succeeded in controlling the left/right-handed helical twist of these polymers, which can control how these polymers may emit circularly polarized light. Such emission is relevant in the coming generation of new display applications (OLEDs).
Exploitation Route New conductive materials
New sensors
New light-emitting materials
Sectors Aerospace, Defence and Marine,Chemicals,Construction,Creative Economy,Digital/Communication/Information Technologies (including Software),Electronics,Energy,Environment,Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology,Security and Diplomacy

URL http://www-jrn.ch.cam.ac.uk
 
Description Jake Greenfield, one of the project's principals, was selected to present his work on this project at the STEM for Britain event in Parliament (http://www.setforbritain.org.uk/2017event.asp) on 13 March 2017. This competitive selection provided a greater depth of understanding of the fundamental problems addressed in this project to our nation's decision-makers.
First Year Of Impact 2017
Sector Government, Democracy and Justice
Impact Types Societal

 
Title Research data supporting "Vibrationally Assisted Intersystem Crossing in Benchmark Thermally Activated Delayed Fluorescence Molecules" 
Description Raw data for manuscript titled 'Vibrationally-assisted intersystem crossing in benchmark thermally activated delayed fluorescence molecules.' Data includes absorption and photoluminescence spectra for 2CzPN and 4CzIPN (Fig1b_Abs_2CzPN, Fig1b_Abs_4CzIPN, Fig1b_PL_2CzPN, Fig1b_PL_4CzIPN); transient electron spin resonance spectra for 2CzPN and 4CzIPN (Fig2c_2CzPN_0p4us, Fig2d_4CzIPN_0p4us); probability distributions for zero-field splitting in 2CzPN and 4CzIPN (Fig3a_2CzPN_ZFS_probability_distribution, Fig3b_4CzIPN_ZFS_probability_distribution); plots of zero-field splitting as a function of overlap index in 2CzPN and 4CzIPN (Fig3c_2CzPN_ZFS_overlap_idx, Fig3d_4CzIPN_ZFS_overlap_idx); and density plots (field versus time) of transient electron spin resonance spectra of 2CzPN and 4CzIPN (FigS1_TrESR_2CzPN_420nm_exc, FigS1_TrESR_4CzIPN_460nm_exc). 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes