Comment on "Sexism in Academia is Bad for Science and a Waste of Public Funding".

A recent comment by Boivin et al. urges academia and governments to address sexism and fight bias at higher education and research institutions as losing female academics is costing science and society too much. Herein, I discuss further underlying reasons of sexism in academia and the importance of a deep dive into the causes of inequity at individual faculty and school levels to develop bespoke and enforceable gender equity plans, the importance of not using basic statistic as the only tool to measure equity/inequity as well as how key performance indicators could be better used to advance gender equity and end sexism in academia.

Waste to resource recovery at a marina: Empirical evidence of upstream and downstream innovation for circularity.

In 2021, an Australian research centre partnered with a regional marina and shipyard where 90 businesses build, refit, and maintain boats in premium condition. Tenants and owners grapple with environmental waste management issues. Since there is a gap in applying action research but numerous calls to co-produce solutions and participate in translating ideas into practice, action research was used in this case study involving upstream and downstream innovation for circularity. Mixed methods data was collected through interviews, stakeholder workshops, and waste audits. A strategic action plan was created for closing the loop on waste. Interventions included tackling toxic, degradable products with natural alternatives, trading and remanufacturing materials to extend product life cycles, testing problematic materials, and pursuing product stewardship. This study is novel because it extends diffusion of innovation theory to real-world impact through a co-innovation process. Results underscore that ongoing achievements depend on properly sorting waste, accessing reprocessing facilities, and maintaining dedicated staff and partnerships, especially legislative support for making continuous improvement.

Life Cycle Assessment in a Nutshell-Best Practices and Status Quo for the Plastic Sector.

Life cycle assessment (LCA) is an internationally standardized methodology to evaluate the potential environmental impacts of products and technologies and assists in lowering their negative environmental consequences. So far, extensive knowledge of LCA-their application and interpretation-is restricted to experts. However, the importance of LCA is increasing due to its application in business, environmental, and policy decision-making processes. Therefore, general knowledge of LCA is critically important. The current work provides an introduction to LCA for non-experts discussing important steps and aspects and therefore can be used as a starting point for LCA. In addition, a comprehensive checklist for non-experts with important content and formal aspects of LCA is provided. Specific aspects of LCA for the plastics sector along the value chain are also discussed, including their limitations.

Photostationary State in Dynamic Covalent Networks.

We explore a cross-linked polymer network based on a visible light photodynamic [2 + 2] cycloaddition driven by styrylpyrene chemistry. Based on a polymer backbone with pendent styrylpyrene units, the network can be formed by using λ = 450 nm irradiation. Upon irradiation with λ = 340 nm, a photostationary state is generated within the network with ∼17% of the styrylpyrene units open compared to close to 2% in the visible light cured state. The limited fraction of open [2 + 2] couples is caused by their proximity and is in sharp contrast to solution experiments on the photoreactive moiety. Thus, the polymer network retains its mechanical properties even at the photostationary point. We hypothesize that the application of an additional stimulus could serve as a second gate for inducing network disintegration by spacing the [2 + 2] units during ultraviolet irradiation.

Size-controlled synthesis of bioinspired polyserotonin nanoparticles with free radical scavenging activity.

Polyserotonin-based nanoparticles are a new class of bioinspired nanomaterial with recently demonstrated therapeutic potential for future clinical applications. It is therefore important to establish a robust and rapid method of synthesizing polyserotonin nanoparticles (PSeNP) in the size range ideal for in vivo utilization. Since the formation of PSeNP is base-catalyzed, here we report the influence of solution pH, in the presence of different base systems, on the kinetics of PSeNP formation and physico-chemical properties of the resulting nanoparticles. We show that the rate of formation and the size of PSeNP depend on both the nature of the base and the initial pH of the reaction. We have also improved the kinetics of particle formation by performing the synthesis at an elevated temperature (60 °C), leading to a dramatic reduction in synthesis time from days to hours. This presents a significant advance in the efficiency of PSeNP synthesis and provides a facile approach in tuning the size of nanoparticles to suit various applications. Furthermore, we show that similar to serotonin, PSeNP also exhibits free radical scavenging property. Our results demonstrate that PSeNP has the potential to become a key player in the advancement of nanotechnology-mediated antioxidative therapy.

Mapping Photochemical Reactivity Profiles on Surfaces.

Herein, we introduce a comprehensive methodology to map the reactivity of photochemical systems on surfaces. The reactivity of photoreactive groups in solution often departs from their corresponding solution absorption spectra. On surfaces, the relationship between the surface absorption spectra and reactivity remains unexplored. Thus, herein, the reactivity of an o-methylbenzaldehyde and a tetrazole, as ligation partners for maleimide functionalized polymers, was investigated when the reactive moieties are tethered to a surface. The ligation reaction of tetrazole functionalized surfaces was found to proceed rapidly leading to high grafting densities, while o-methylbenzaldehyde functionalized substrates required longer irradiation times and resulted in lower surface coverage at the same wavelength (330 nm). Critically, wavelength resolved reactivity profiles were found to closely match the surface absorption spectra, contrary to previously reported red shifts in solution for the same chromophores.

Chemiluminescent read-out of para-fluoro-thiol reaction events.

We exploit the fluoride that is released via the para-fluoro-thiol reaction (PFTR) to cleave silyl ethers, turning the PFTR into an effective self-reporting chemiluminescence (CL) probe. The cleavage induces chemiluminescence and hence provides an optical read-out for the conversion of the PFTR. The PFTR chemiluminescence read-out is established on small molecule thiols, and subsequently expanded to polymers and networks.

Plastics and the Environment-Current Status and Challenges in Germany and Australia.

Polymers and plastics play a very important part in the modern world and contribute to people's wellbeing and comfort. However, products made of them are contributing to land- and marine-based environmental pollution due to littering and other ways of emission, and therefore threaten ecosystems worldwide. However, waste management and responses by governments and the consumer differ strongly from country to country. The current article provides an overview of several important aspects of polymer waste and plastic pollution as well as describes selected strategies to mitigate these using examples from Germany and Australia, and therefore aims to contribute to the resolution of the ever-increasing problem of unsustainable plastic consumption, disposal, and pollution.

On-demand acid-gated fluorescence switch-on in photo-generated nanospheres.

Herein, we introduce a fast, additive-free, ambient temperature photochemical approach - utilising the novel Diels-Alder cycloaddition of a photo-active ortho-methylbenzaldehyde (oMBA) with a terminal alkyne - for preparing functional acid-sensitive profluorescent nano-/microspheres in one step. Not previously reported, the possibility of applying such a reaction in the context of particle synthesis provides new possibilities for particle design, where multi-step reactivity can be gated into distinct steps. First, a photochemically-gated particle formation step yields a material possessing a reactive, spring-loaded intermediate at every cross-linking point. A second, on-demand step to initiate fluorescence generation subsequently imparts the properties of the chemical transformation to the material itself. The synthesised particles are narrow-disperse with an average diameter ranging from 170-380 nm.

Critical Assessment of the Application of Multidetection SEC and AF4 for the Separation of Single-Chain Nanoparticles.

The intramolecular chain collapse of linear precursors with systematic variation of molar mass and ligation group density (5, 15, and 30 mol %) into single-chain nanoparticles (SCNPs) was studied by two different separation approaches. The efficiency of size exclusion chromatography with quadruple detection (SEC-D4) was compared to asymmetrical field flow fractionation hyphenated to quintuple detection (AF4-D5) in organic solvent. The application of the unique combination of advanced detection to different separation principles opens up the opportunity to critically evaluate the determination of molar masses and different types of radii for an in-depth understanding of the structural properties affected by the internal folding process. This is achieved by a detailed comparison of assets, drawbacks, and limitations of these approaches based on the systematical screening of different chain lengths and sizes of the precursors and the SCNPs. Furthermore, an alternative strategy for quantitative determination of intramolecular ligation density by a combination of AF4 and UV detection is introduced.

Two Grapes Short of a Fruit Salad: Raspberry-, Strawberry-, and Seedpod-Like Organic Microspheres via Colloidal Nanotemplating.

The morphology of surfaces critically influences their interaction with the surrounding phase. Herein, we report a modular approach for the synthesis of organic-inorganic raspberry-, strawberry-, and seedpod-like particles to template the porosity of superficially porous particles. Divinylbenzene (DVB) microspheres were employed as core particles, which were modified with polar and nonpolar polymer shells. Subsequently, silica nanoparticle templates were covalently tethered to said particles. Further grafting of polymer shells and subsequent template removal yielded superficially porous core-shell particles. In addition, we introduce a facile procedure for the synthesis of superficially porous particles without distinguishable core-shell morphology. Organic seedpod-like particles were prepared from DVB and silica templates, yielding superficially porous particles after template removal. The surface morphology of the templated particles was investigated via scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) was performed to prove the chemical modification of the particle surfaces.

Self-Propagated para-Fluoro-Thiol Reaction.

We introduce a protecting-group-free concept for the powerful para-fluoro-thiol reaction (PFTR) employing a source of fluoride ions as base. The reaction is shown to be self-propagating, with under-stoichiometric amounts of base, thus effectively foregoing the need for high base concentrations. Careful tuning of the solvent-thiol combination allows for quantitative conversion, in some cases within a short timeframe, when only minimal amounts of base are used, allowing the PFTR reaction to essentially proceed base-free.

A Photochemical Ligation System Enabling Solid-Phase Chemiluminescence Read-Out.

The peroxyoxalate chemiluminescence (PO-CL) reaction is among the most powerful and versatile techniques for the detection of hydrogen peroxide (H2 O2 ) and has been employed in various biological and chemical applications over the past 50 years. However, its two-component nature (peroxyoxalate and fluorophore) limits its use. This contribution introduces an innovative and versatile photochemical platform technology for the synthesis of inherently fluorescent PO probes by exploiting the nitrile imine-mediated tetrazole-ene cycloaddition (NITEC) reaction. In the presence of hydrogen peroxide, the pioneered "2-in-1" molecule emits either yellow or blue light, depending on tetrazole (Tz) structure. Even in the absence of base, the emitted light remains visible and H2 O2 could be detected in the nanomolar range. Critically, the PO-Tz can be readily incorporated into polymeric materials. As a first application of this promising material, a tailor-made PO-Tz is grafted on poly(divinylbenzene) (PDVB) particles to enable solid-phase chemiluminescence on microspheres.

Quantifying Solvent Effects on Polymer Surface Grafting.

When grafting polymers onto surfaces, the reaction conditions critically influence the resulting interface properties, including the grafting density and molar mass distribution (MMD) on the surface. Herein, we show theoretically and experimentally that the application of poor solvents is beneficial for the "grafting-to" approach. We demonstrate the effect by grafting poly(methyl methacrylate) chains on silica nanoparticles in different solvents and compare the MMD of the polymer in solution before and after grafting via size exclusion chromatography (SEC). The shorter polymer chains are preferentially grafted onto the surface, leading to a distortion effect between the MMD in solution and on surfaces. The molecular weight distortion effect is significantly higher for ethyl acetate (good solvent quality, difference in Mw surface to solution 14%) than for N,N-dimethylacetamide (poor solvent quality, 6%). The difference in MMD on the surface to the solution significantly affects both the surface properties (e.g. the grafting densities) and their determination.

Dynamic Nitroxide Functional Materials.

A substrate-independent and versatile coating platform for (spatially resolved) surface functionalization, based on nitroxide radical coupling (NRC) reactions and the formation of thermo-labile alkoxyamine functional groups, was introduced. Nitroxide-decorated poly(glycidyl methacrylate) (PGMA) microspheres, obtained through bioinspired copolymer surface deposition using dopamine and a nitroxide functional dopamine derivative as monomers, were conjugated with small functional groups in a rewritable process. Reversible coding of the nitroxide functional microspheres by NRC and decoding through thermal alkoxyamine fission were monitored and characterized by electron paramagnetic resonance (EPR) spectroscopy and X-ray photoelectron spectroscopy (XPS). In addition, this nitroxide coating system was exploited in "grafting-to" polymer surface ligations of poly(methyl methacrylate) (PMMA) and poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA) in spatially confined areas. Polymer strands terminated with an Irgacure 2959 (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone) photoinitiator were obtained through chain-transfer polymerization, and subsequently coupled to nitroxide-immobilized poly(dopamine) (PDA)-coated silicon substrates by using rapid photoclick NRC reactions. Light-driven polymer surface coding was visualized by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and XPS imaging.

TEMPO Driven Mild and Modular Route to Functionalized Microparticles.

The synthesis of crosslinked polymeric microspheres (3.8-15.0 µm) via (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) initiated thiol-ene dispersion polymerization under ambient conditions is reported for the first time. The initiating ability of TEMPO for the thiol-ene reaction is validated by electron paramagnetic resonance (EPR) and 1 H nuclear magnetic resonance (NMR) spectroscopy on model reactions between 1-octadecanethiol and two electron deficient enes, n-butylacrylate and divinyl sulfone. Critically, the TEMPO resonance observed in the EPR spectra decreases with time when TEMPO is mixed with thiol and an electron deficient ene. The 1 H NMR spectra demonstrate formation of up to 90% of thioether under ambient conditions. Based on these model reactions, a variety of crosslinked polymeric microspheres are synthesized with excellent morphological stability using poly(vinyl pyrrolidone) as surfactant. The ability of the microspheres for a second TEMPO initiated thiol-ene reaction is demonstrated by the ligation of fluorescein-5-maleimide (an ene) to the microspheres' surface containing excess of thiol functionality and by ligation of cysteine (containing a thiol group) to the microspheres' surface containing an excess of ene functionality. The synthesized polymeric microspheres are characterized using scanning electron microscopy, differential scanning calorimetry, Fourier-transform infrared spectroscopy, zeta potential, and X-ray photoelectron spectroscopy.

Polymer on Top: Current Limits and Future Perspectives of Quantitatively Evaluating Surface Grafting.

Well-defined polymer strands covalently tethered onto solid substrates determine the properties of the resulting functional interface. Herein, the current approaches to determine quantitative grafting densities are assessed. Based on a brief introduction into the key theories describing polymer brush regimes, a user's guide is provided to estimating maximum chain coverage and-importantly-examine the most frequently employed approaches for determining grafting densities, i.e., dry thickness measurements, gravimetric assessment, and swelling experiments. An estimation of the reliability of these determination methods is provided via carefully evaluating their assumptions and assessing the stability of the underpinning equations. A practical access guide for comparatively and quantitatively evaluating the reliability of a given approach is thus provided, enabling the field to critically judge experimentally determined grafting densities and to avoid the reporting of grafting densities that fall outside the physically realistic parameter space. The assessment is concluded with a perspective on the development of advanced approaches for determination of grafting density, in particular, on single-chain methodologies.

Engineering Nitroxide Functional Surfaces Using Bioinspired Adhesion.

We pioneer a versatile surface modification strategy based on mussel-inspired oxidative catecholamine polymerization for the design of nitroxide-containing thin polymer films. A 3,4-dihydroxy-l-phenylalanine (l-DOPA) monomer equipped with a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-derived oxidation-labile hydroxylamine functional group is employed as a universal coating agent to generate polymer scaffolds with persistent radical character. Various types of materials including silicon, titanium, ceramic alumina, and inert poly(tetrafluoroethylene) (PTFE) were successfully coated with poly(DOPA-TEMPO) thin films in a one-step dip-coating procedure under aerobic, slightly alkaline (pH 8.5) conditions. Steadily growing polymer films (∼1.1 nm h-1) were monitored by ellipsometry, and their thicknesses were critically compared with those obtained from atomic force microscopic cross-sectional profiles. The heterogeneous composition of surface-adherent nitroxide scaffolds examined by X-ray photoelectron spectroscopy was correlated to that examined by in-solution polymer analysis via high-resolution electrospray ionization mass spectrometry, revealing oligomeric structures with up to six repeating units, mainly composed of covalently linked dihydroxyindole along the polymer backbone. Critically, the reversible redox-active character of the nitroxide-containing polymer scaffolds was investigated by cyclic voltammetric measurements, revealing a convenient and facile access route to electrochemically active nitroxide polymer coatings with potential application in electronic devices such as organic radical batteries.

Counting the Clicks in Fluorescent Polymer Networks.

We introduce a fluorescence-based methodology enabling the quantification of ligation points in photochemically prepared polymer networks. Well-defined α,ω-tetrazole-capped polymer strands prepared via RAFT polymerization are crosslinked under UV irradiation by a trimaleimide via nitrile imine mediated tetrazole-ene cycloaddition. Thus, for each linkage point a fluorescent pyrazoline ring is formed, resulting in fluorescent networks, which are degradable by aminolysis of the trithiocarbonate functionalities, leading to soluble fragments. The fluorescence emission of the soluble network fragments correlates directly with the number of pyrazoline moieties originally present in the network, thus providing a direct measure of the number of ligation points constituting the network. The herein introduced strategy based on a fluorescence readout is a powerful yet simple approach to quantify network formation processes applicable to a wide class of polymers accessible via RAFT.

Dual-Gated Microparticles for Switchable Antibody Release.

We pioneer the design of dual-gated microparticles, both responsive to changes in temperature and pH, for stimuli-responsive chromatography targeted at the efficient separation of antibodies. Dual-gated microspheres were synthesized by introducing RAFT-based thiol-terminal block copolymers of poly(N-isopropylacrylamide-b-4-vinylpyridine) (P(NIPAM-b-4VP, 4800 ≤ Mn/Da ≤ 10 000, featuring block length ratios of 29:7, 29:15, and 29:30, respectively) by thiol-epoxy driven ligation to the surface of poly(glycidyl methacrylate) (PGMA) microparticles (10-12 µm), whereby the 4-vinylpyridine units within the lateral chain enable protein binding. The switchable protein release abilities of the resulting microparticle resins are demonstrated by adsorption of immunoglobulins at 40 °C and pH 8 and their release at 5 °C or pH 3, respectively. We demonstrate that P(NIPAM29-b-4VP30)-grafted PGMA particles show a maximum adsorption capacity for immunoglobulins of 18.9 mg mL-1 settled resin at 40 °C/pH 8, whereas the adsorption capacity decreased to 7.5 mg mL-1 settled resin at 5 °C while retaining the pH value, allowing the unloading of the chromatographic column by a facile temperature switch. Critically, regeneration of the dual-gated microspheres became possible by lowering the pH to 3.