Functional polymeric microspheres are of great interest as they have high potential as functional scaffolds in material science applications. Highly cross‐linked poly(divinyl benzene) (pDVB) ...microspheres can be synthesized via the precipitation polymerization technique. Recently, various methods of controlled polymerization techniques (e.g., atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer (RAFT), and anionic ring‐opening polymerization (AROP)) and highly orthogonal conjugation methods (e.g., copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition of azides and terminal alkynes (CuAAc), thiol‐ene addition and RAFT hetero Diels–Alder cycloaddition (RAFT‐HDA)) have been applied to functionalize microspheres via the “grafting from” and “grafting to” approaches. The synthesis of pDVB microspheres, their subsequent modification via grafting of polymer strands to the surface, and the characterization of the obtained functional particles are reviewed.
Polymeric microspheres can be used as functional scaffolds in materials science and analytical applications. Poly(divinyl benzene) microspheres are conveniently functionalized by controlled/living polymerization methods (e.g., reversible addition fragmentation chain transfer – RAFT, atom transfer radical polymerization – ATRP) and by highly orthogonal click reactions, resulting in functional polymeric microspheres.
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.
Many early, mid‐, and advanced career female academics face sexism at their institutions as highlighted by a recent comment from Boivin et al. The current comment discusses additional underlying causes of sexism in academia and additional tools to improve equity in academia. Ending sexism in academia is a true global challenge.
In the current contribution, we discuss the application and potential of the versatile
para
-fluoro-thiol reaction in the context of synthesis and modification of polymers and materials made thereof. ...General reaction parameters such as solvent, temperature, and activator are reviewed. In addition, orthogonality towards some important ligation methods is examined. A brief description of the applications in which the PFTR was employed is finally provided. We postulate that the PFTR will come to be increasingly considered as a powerful complement to well-established coupling methodologies, due to the generally high selectivity of pentafluorophenyl moieties towards thiols under mild, metal-free conditions.
The current literature describing the application of the
para
-fluoro-thiol reaction in the realm of macromolecular chemistry and the future of this coupling strategy are discussed.
Reversible addition–fragmentation chain transfer (RAFT) chemistry can be effectively employed to construct macromolecular architectures of varying topologies. The present article explores the ...principle design routes to star, block, and comb polymers in the context of theoretical design criteria for the so‐called Z‐ and R‐group approaches. The specific advantages and disadvantages of each approach are underpinned by selected examples generated in the CAMD laboratories. In particular, we demonstrate how the modeling of full molecular weight distributions can be employed to guide the synthetic effort. We further explore the theory and practice of generating amphiphilic block copolymer structures and their self‐assembly. In addition, the article foreshadows how modern synthetic techniques that combine RAFT chemistry with highly orthogonal click chemistry can be employed as a powerful tool that furthers the enhancement of macromolecular design possibilities to generate block (star) copolymers of monomers with extremely disparate reactivities. Finally, the ability of RAFT chemistry to modify the surface of well‐defined nano‐ and microspheres as devices in biomedical application is detailed.
The synthesis of single chain nanoparticles (SCNPs) is a vibrant field in macromolecular science, enabled by a rich variety of synthetic strategies to induce macromolecular chain folding. Due to the ...decrease of the hydrodynamic volume upon folding, SCNP formation is typically characterized by a shift towards higher elution volumes in size exclusion chromatography (SEC). However, a step-change in the methodologies for SCNP analysis is required for the in-depth understanding of the nature of intramolecular polymer folding and internal SCNP structure, which is critical to enable their application as catalytic nanoreactors. Herein, we exploit a unique combination of small-angle neutron scattering (SANS),
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F NMR spectroscopy, and quadruple detection SEC to generate an encompassing and systematic view of the folded morphology of poly(
tert
-butyl acrylate) based-SCNPs as a function of their reactive group density (5, 15, and 30 mol%) and absolute molar mass (20, 50, 100 kDa). In addition to detailed morphological insights, we establish that the primary factor dictating the compaction of SCNPs is their reactive group density, which is ineffective below 5 mol%, reaching maximum compaction close to 30 mol%. The molar mass of the precursor polymers has a minor impact on how an SCNP compacts for molar masses above 20 kDa.
The synthesis of single chain nanoparticles (SCNPs) is a vibrant field in macromolecular science. However, to achieve an in-depth understanding of the nature of intramolecular polymer folding, a step-change in the methodologies for SCNP analysis is required.
We report the functionalization of cross-linked poly(divinylbenzene) (pDVB) microspheres using both thiol−ene chemistry and azide−alkyne click reactions. The RAFT technique was carried out to ...synthesize SH-functionalized poly(N-isopropylacrylamide) (pNIPAAm) and utilized to generate pNIPAAm surface-modified microspheres via thiol−ene modification. The accessible double bonds on the surface of the microspheres allow the direct coupling with thiol-end functionalized pNIPAAm. In a second approach, pDVB microspheres were grafted with poly(2-hydroxyethyl methacrylate) (pHEMA). For this purpose, the residual double bonds on the microspheres surface were used to attach azide groups via the thiol−ene approach of 1-azido-undecane-11-thiol. In a second step, alkyne endfunctionalized pHEMA was used to graft pHEMA to the azide-modified surface via click-chemistry (Huisgen 1,3-dipolar cycloaddition). The surface-sensitive characterization methods X-ray photoelectron spectroscopy, scanning-electron microscopy and FT-IR transmission spectroscopy were employed to characterize the successful surface modification of the microspheres. In addition, fluorescence microscopy confirms the presence of grafted pHEMA chains after labeling with Rhodamine B.
Increased waste in health care is a widespread problem. Currently, modern clinical practices favour single-use products and pre-packaged supply kits. Many of these consist of various types of ...plastics. By weight, up to 25 per cent of total hospital waste is plastics. Common plastics used are polyethylene terephthalate, polypropylene, polyethylene, polyvinylchloride and polyurethane. Polyethylene terephthalate represents the highest volume, and accounts for 40 per cent of the plastics used in operating rooms. Health care has an enormous ecological footprint. Around the world, health care waste management strategies and clinician activities are starting to address how health care affects our planet and public health. Recovery of valuable waste, or product stewardship, is one of these strategies. In many countries, product stewardship in health care is still non-existent or unregulated. Clinicians and health service organisations must make product stewardship in health care an integral part of sustainable procurement and health care business activities. In addition, sustainable solutions require the engagement of suppliers of plastic packaging who can contribute to reducing waste in health care and minimising the impact of plastics on the environment and public health.
Brown algae are the main source of polysaccharides such as fucoidan and alginate, which can be used to develop a wide range of bioactive and polymer materials. In this study, sodium alginate and ...fucoidan were sequentially extracted using thermochemical, microwave, ultrasonic and sub critical water treatments of untreated and ethanol-pre-treated brown algae, Ascophyllum nodosum. Extraction was achieved using a solvent solution consisting of a 1:2 M ratio of choline chloride to glycerol (ChGl) in 70% water (w/w) for initial treatment to extract fucoidan, followed by Na2CO3 treatments for alginate extraction. Microwave extraction was shown to be the most advantageous treatment for alginate extraction, with the greatest biomass extracted (46.2%), purity (33.43% combined mannuronic and guluronic acid content), and molecular weight, whilst indicating an increased bioactive capacity associated with co-extracted polyphenolic content. However, using ChGl for fucoidan extraction resulted in a large fraction of the solvent remaining within the fucoidan. This is evidenced by up to 39% of the fucoidan consisting of glycerol. The extracted alginate has the potential as a bioactive polysaccharide, whilst the fucoidan would require further purification.
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•Glycerol and Choline Chloride based Biorefinery extraction of fucoidan and alginate from A. nodosum.•Comparison of thermochemical, ultrasonic, microwave and subcritical water treatments.•Glycerol from solvent found in large fraction of extracted fucoidan.•Microwave extraction proved the most advantageous for targeted polysaccharides.
Reversible addition−fragmentation chain transfer (RAFT) polymerization was applied to radiation-induced graft polymerization of styrene from cellulose. The grafting of styrene from cellulose ...substrates using the chain transfer agent cumyl phenyldithioacetate was confirmed by Raman and X-ray photoelectron spectroscopy, differential scanning calorimetery, thermogravimetric analysis, scanning electron microscopy, and contact angle analysis. Grafted polystyrene chains were cleaved from the cellulose surface by acidic hydrolysis of the cellulose. The number-average molecular weight and polydispersity index of the grafted and the free (nongrafted) polystyrenes obtained under identical conditions were determined by size exclusion chromatography. Grafted and nongrafted polystyrenes have almost the same (near theoretical) molecular weight and narrow polydispersity, thus proving for the first time the control of the grafting process mediated via RAFT without any prior functionalization of the surface.
An in‐depth investigation of the network topology for a series of sodium acrylate hydrogels synthesized via conventional free radical polymerization (FRP) and reversible addition–fragmentation chain ...transfer (RAFT) polymerization is conducted. The role of the RAFT agent on the crosslinking process is demonstrated on a model system upon analysis of the reaction mixture via size‐exclusion chromatography before the gelation point. For a comprehensive study, both the impact of the amount of RAFT agent and of the degree of crosslinking on the microstructure of the final product are systematically investigated. In addition to swelling experiments and oscillatory shear rheology measurements, the resulting networks are analyzed via low‐field proton nuclear magnetic resonance (1H‐NMR) techniques such as transverse relaxation and double‐quantum coherence to evaluate the network mobility, which is then correlated to structural inhomogeneity. A broader mobility distribution is observed for the RAFT mediated networks compared to the FRP samples, which can be assigned to a higher content of dangling ends in the former case. The results are further elaborated to propose a mechanism for network formation in presence of a RAFT agent.
The network topology of a series of poly(sodium acrylate) hydrogels, synthesized either via free radical polymerization or reversible addition–fragmentation chain transfer polymerization (RAFT), is investigated via 1H‐NMR techniques. A broader mobility distribution is observed for the RAFT mediated networks, assignable to a higher content of dangling ends, arising from a lower amount of crosslinking points per chain.
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