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Solution-processing of multilayered Organic Light Emitting Diodes (OLEDs) remains a challenge that is often addressed by cross-linking polymer precursors into insoluble networks. Herein, we blend an emissive polymer carrying a Thermally Activated Delayed Fluorescence (TADF) emitter and a host species with a photo-cross-linkable polymer containing ortho-methylbenzaldehyde and maleimide groups as reactive cross-linkers to form a Semi-Interpenetrating Polymer Network (SIPN) upon irradiation at 365 nm. The progress of the cross-linking via Diels–Alder [4 + 2]-cycloaddition is monitored by FT-IR-spectroscopy and is correlated with the solvent resistance of the SIPN. Furthermore, the influence of the molecular weight and the cross-linker content on the efficiency of the cross-linking are investigated. The resulting polymer films show a high solvent resistance evidenced by photoluminescence and AFM measurements and are thus suitable for a successive solution-processed layer. Furthermore, a comonomer carrying the commercial host molecule 1,3-bis(N-carbazolyl)benzene (mCP) was synthesized in high yields, copolymerized and integrated in the emissive SIPN with good resistance against organic solvents. Lastly, the polymer blends were processed with an ink-jet printer and turned into an insoluble SIPN.

Waste production associated with the use of non-degradable materials in packaging is a growing cause of environmental concern, with the polyurethane (PU) class being notorious for their lack of degradability. Herein, we incorporate photosensitiveortho-Nitrobenzyl units into PUs to achieve controllable photodegradability. We performed their photolysis in solution and thin films which can inform the design of degradable adhesives.

We introduce a red-shifted tetrazole that is able to undergo efficient nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) under blue and green light irradiation. We provide a detailed wavelength-dependent reactivity map, and employ a number of LEDs for high-conversion small molecule and polymer end-group modification.

Light as a non-invasive and clean external stimulus provides a facile route towards macromolecular design. Herein, we demonstrate the scalable synthesis of catalyst-free, visible-light mediated photo-oligomers and-polymers via a step-growth mechanism. Both a batch approach and a continuous photoflow setup are employed to investigate the degree of polymerisation and scalability. Violet blue light at 415 nm triggers [2 + 2]-cycloadditions of a pyrene-chalcone derivative to grow linear step-growth polymers, while subsequent UV-B light irradiation triggers the depolymerisation. The process was monitored online via a photoflow-high resolution electrospray ionisation mass spectrometry setup (ESI-MS). Size exclusion chromatography provides additional offline analysis of both the polymerisation and photodegradation over time. By changing the colour of light, photopolymers can be recycled and reshaped, allowing these macromolecular precursors to be applied to reversible and photodegradable material design.

Amongst emissive materials for organic light emitting diodes (OLEDs), thermally activated delayed fluorescence (TADF) materials have shown substantial promise in the last few years. For OLEDs, solution processable and printable emissive materials are highly desirable as printing allows for precise patterning without masks, enables deposition of nanometer scale thicknesses and results in minimal wastage of material. Herein, we introduce a solution processable TADF emitting polymer as an emissive material for OLEDs. The bespoke polymer structure features the TADF emitter 4-(9H-carbazol9-yl)-2-(3′-hydroxy-[1,1′-biphenyl]-3-yl)isoindoline-1,3-dione as a pendant group on a poly(methyl methacrylate) based polymer chain. The resulting OLEDs have a peak emission wavelength of 520 nm with a maximum luminance of around 4700 cd m−2. The peak emission wavelength can be blue-shifted by exciplex management to achieve a peak wavelength of 494 nm. Critically, we employed the TADF-containing polymer system to ink-jet print OLEDs, demonstrating that such polymers are viable for printable OLEDs.

Herein, we push the limits of single chain nanoparticle (SCNP) analysis to directly observe the specific compaction of defined single chains dependent on the number of compaction steps utilizing a copolymer consisting of styrene and chloromethylstyrene, compacted via Friedel-Crafts alkylation. Our study critically expands the boundaries of SCNP characterization via size exclusion chromatography coupled with high resolution electrospray ionization mass spectrometry (SEC-ESI-MS), highlighting the unique compositional and structural information that can be derived via this technique.

There remain several key challenges to existing therapeutic systems for cancer therapy, such as quantitatively determining the true, tissue-specific drug release profile in vivo, as well as reducing side-effects for an increased standard of care. Hence, it is crucial to engineer new materials that allow for a better understanding of the in vivo pharmacokinetic/pharmacodynamic behaviours of therapeutics. We have expanded on recent "click-to-release" bioorthogonal pro-drug activation of antibody-drug conjugates (ADCs) to develop a modular and controlled theranostic system for quantitatively assessing site-specific drug activation and deposition from a nanocarrier molecule, by employing defined chemistries. The exploitation of quantitative imaging using positron emission tomography (PET) together with pre-targeted bioorthogonal chemistries in our system provided an effective means to assess in real-time the exact amount of active drug administered at precise sites in the animal; our methodology introduces flexibility in both the targeting and therapeutic components that is specific to nanomedicines and offers unique advantages over other technologies. In this approach, the in vivo click reaction facilitates pro-drug activation as well as provides a quantitative means to investigate the dynamic behaviour of the therapeutic agent.

With the ever-increasing complexity of polymeric structures obtained via contemporary synthetic strategies, their precision analysis is a challenging task. Thus, powerful analytical techniques must be explored to allow for an in-depth characterization of complex polymers, yielding chemical information at a sensitivity beyond that of commonly applied analysis methods such as conventional size exclusion chromatography (SEC) and NMR spectroscopy. Here, a tutorial overview on the hyphenation of SEC to electrospray ionization mass spectrometry (ESI-MS) is presented, highlighting the resulting benefits in the context of polymer characterization. First, the capability of obtaining structural information of polymers as well as verifying polymer analogous transformations via SEC-ESI-MS is outlined. Importantly, the wide applicability of SEC-ESI-MS is highlighted, e.g. by its use for the determination of radical polymerization rate coefficients, the detailed investigation of radical photoinitiations systems and the examination of absolute molecular weight distributions of polymers. The current tutorial review thus aims to demonstrate the power of SEC-ESI-MS for the characterization of complex polymers and to underline the high potential it has to become a powerful and popular analytical technique in polymer chemistry.

We introduce the preparation and ring-opening polymerization of a nitroxide containing carbonate monomer. Using 1,8-diazabicyclo undec-7-ene (DBU) and a thiourea as the catalyst system, we demonstrate that the free radical moiety of the monomer has no influence on the ring-opening copolymerization with D/L-lactide in a wide range of compositions between 10% and 80% of the nitroxide monomer, which can be readily controlled by the comonomer composition in the polymerization mixture. The copolymers exhibit narrow and monomodal mass distributions with number average molar masses between 6000 g·mol−1 to 7000 g·mol−1 and low dispersities below 1.1. The free radical functionality is retained during the polymerization as demonstrated by electron spin resonance (EPR) spectroscopy. High-resolution mass spectrometry coupled to size exclusion chromatography allowed an in-depth analysis of the copolymers showing well-defined linear polymer chains with excellent endgroup fidelity. Furthermore, the molar mass of the polymers was controlled by the monomer to initiator ratio which led to copolymers of up to 19 500 g·mol−1.

We pioneer an approach for the visualization of pH-controlled molecular release of a fluorescent drug from a nitroxide polymer which combined yields a profluorescent system. A methacrylate-based terpolymer, bearing water-solubilizing triethylene-glycol chains, unpaired spins in the form of nitroxide and hydrazone-bound doxorubicin was synthesized to explore the possibilities of release quantification from profluorescent assemblies. Critically, we establish the fluorescence-silencing effect of polymer-bound nitroxides on covalently attached fluorophores and the overall accessibility of such constructs. The facile approach towards a functional assembly shown here provides an easy-to-assemble construct for complex delivery architectures towards applications in theranostics.

We introduce a mild and efficient avenue to induce the folding of single chain polymer nanoparticles (SCNPs) using visible light. The versatility of the method is based on three folding mechanisms exploiting tetrazole chemistry, i.e., nitrile imine-mediated tetrazole-ene cycloaddition (NITEC), nitrile imine carboxylic acid ligation (NICAL) as well as nitrile imine self-dimerization. To our knowledge, this visible light driven approach is the to-date mildest avenue to fold single polymer chains into compact particles using light.

We introduce a mass spectrometric access route to nitroxide containing polymers via high resolution electrospray ionization mass spectrometry (HR ESI MS), a polymer class that is – due to the presence of unpaired spins – highly challenging to analyze via NMR techniques. The nitroxide content within the polymer chain structure was varied between 11.3 and 29.1 mol% in a statistical copolymer consisting of styrene-stat-4-(chloromethyl)styrene (p(S-stat-CMS), 4800 ≥ Mn/g mol−1 ≥ 11 100), where 4-carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl (4-carboxy-TEMPO) units were attached by post-polymerization modification. By carefully evaluating the isotopic pattern of the nitroxide containing polymers, we demonstrate that the persistent nitroxyl radical retains its structural integrity during the soft ionization process employing spray currents up to 4.3 keV and in-source collision induced dissociation energies up to 30 eV using chloride attachment technology in negative ion mode. Interestingly, high-molecular weight gas-phase aggregates are identified with increasing amounts of nitroxide side-chain functionalization. To further exemplify the power of the introduced mass spectrometric protocol, a well-defined styrene based polymer was synthesized via atom transfer radical polymerization (ATRP, Mn = 5600 g mol−1, Đ = 1.05) containing functional groups, i.e. a terminal cyanuric acid unit and Hamilton Wedge moiety as well as a free nitroxide in the penultimate position to the Hamilton wedge. The intact persistent nitroxide radical at the chain end was unambiguously identified by its isotopic pattern in a highly defined polymer structure.

We pioneer a self-reporting profluorescent release system driven by the thermo-reversible dynamic covalent ligation of chromophores to a lateral polymer chain, whose fluorescence is silenced by unpaired spins of nitroxide moieties prior to release. The introduced technology platform holds significant potential for imaging substrate release events.

We report a visible light responsive moiety capable of generating highly reactive thioaldehydes. Upon irradiation with visible light (420 nm) the pyreneacyl sulfide species undergoes a Norrish II elimination yielding thioaldehydes capable of being trapped by nucleophiles (amines, aminoxys, and thiols), as well as Diels–Alder processes, representing a new versatile ligation platform.

We introduce the high-resolution electrospray ionization mass spectrometric (ESI MS) structural elucidation of polymerized 3,4-dihydroxy-L-phenylalanine (L-DOPA) carrying 1-methoxy-2,2,6,6-tetramethylpiperidin-4-amide groups in the side chain. Critically, our powerful ESI MS platform unambiguously revealed the structurally diverse character of this multifunctional bio-adhesive polymer system.

Here we report the first example of an alkoxyamine derived from an azaphenalene nitroxide, which when exposed to UV-light, readily undergoes homolysis to efficiently and cleanly re-form a nitroxide. This process selectively cleaves the C–O bond of the alkoxyamine and occurs orders of magnitude more rapidly than any other alkoxyamine homolysis previously described in the literature. We demonstrate the use of light to generate a persistent radical effect (PRE) and apply this to undertake radical insertion, radical exchange and proof of concept polymerization reactions.

The current study introduces a tetrazole species able to perform a rapid, visible light induced nitrile imine-mediated tetrazole-ene cycloaddition (NITEC). Full conversion of the tetrazole species under mild, catalyst free conditions is reported. Importantly, the visible light ligation technology is applied as a method for the modification and ligation of polymers featuring the rapid, clean and exclusive formation of the desired cycloadduct.

A simple modular strategy for the synthesis of profluorescent nitroxide containing polymers is described. The incorporation of an epoxide as a pendant functionality on a polymer backbone synthesized using ATRP and subsequent nucleophilic ring-opening with sodium azide gave hydroxyl and azide functionality within a 3-bond radius. Orthogonal coupling chemistry then allowed the independent attachment of fluorophore and nitroxide groups in close proximity, giving rise to a profluorescent polymer. Validation of the viability of these materials as fluorescent sensors is demonstrated through efficient fluorescence switch-on observed when the materials are exposed to a model reductant or carbon-centred radical source.

The current study reports the synthesis and properties of a novel isoindoline nitroxide contg. a benzophenone chromophore fused into the carbon framework. When exposed to UV light, rather than undergoing traditional benzophenone photochem. pathways, the presence of the nitroxide enables an energy transfer process whereby the nitroxide enters an excited state which induces an efficient hydrogen atom transfer from unactivated alkanes.

We describe a novel and facile approach to covalently graft molecules containing stable free radicals onto carbon surfaces including graphene, carbon nanotubes, glassy carbon and carbon fibres. The new technique employs a stable aryl nitroxide radical diazonium tetrafluoroborate salt. The salt may be isolated and added to carbon surfaces in solution, suspension or electrochemically and represents a convenient, versatile and highly efficient means to adorn graphitic materials with large numbers of free radical spin systems

Poly(styrene)-block-poly(ethylene oxide) copolymers synthesized via the combination of reversible addition fragmentation chain transfer (RAFT) polymerization and hetero Diels–Alder (HDA) cycloaddition can be cleaved in the solid state by a retro-HDA reaction occurring at 90 °C. Nanoporous films can be prepared from these polymers using a simple heating and washing procedure.

A series of polymers with a comb architecture were prepared where the poly(olefin sulfone) backbone was designed to be highly sensitive to extreme ultraviolet (EUV) radiation, while the well-defined poly(methyl methacrylate) (PMMA) arms were incorporated with the aim of increasing structural stability. It is hypothesized that upon EUV radiation rapid degradation of the polysulfone backbone will occur leaving behind the well-defined PMMA arms. The synthesized polymers were characterised and have had their performance as chain-scission EUV photoresists evaluated. It was found that all materials possess high sensitivity towards degradation by EUV radiation (E0 in the range 4–6 mJ cm−2). Selective degradation of the poly(1-pentene sulfone) backbone relative to the PMMA arms was demonstrated by mass spectrometry headspace analysis during EUV irradiation and by grazing-angle ATR-FTIR. EUV interference patterning has shown that materials are capable of resolving 30 nm 1:1 line:space features. The incorporation of PMMA was found to increase the structural integrity of the patterned features. Thus, it has been shown that terpolymer materials possessing a highly sensitive poly(olefin sulfone) backbone and PMMA arms are able to provide a tuneable materials platform for chain scission EUV resists. These materials have the potential to benefit applications that require nanopattering, such as computer chip manufacture and nano-MEMS.

Exchange reactions between the isoindoline profluorescent nitroxide 1,1,3,3-tetramethyldibenzo[e,g]isoindolin-2-yloxyl (TMDBIO) and a TEMPO capped polystyrene were carried out. High conversions to the desired products were achieved using only stoichiometric ratios of nitroxide relative to polymer. The scope of this study was expanded by exploiting a di-nitroxide 9,10-bis(5-[1,1,3,3-tetramethylisoindolin-2-yloxy])anthracene (BTMIOA) as a connector between two polymer chains forming PS–nitroxide–PS systems.