The accelerator effect of amine activators N‐methylimidazole and 4‐vinylaniline (4‐VA) on inverse vulcanization and dynamic covalent polymerization (DCP) has been investigated. The sulfur polymer with self‐activation comonomer 4‐VA could also be used for low temperature DCP to incorporate some volatile monomers. Those approaches provide a new synthetic and rate accelerated processes to activate S8 for copolymerization processes with functional comonomers at lower temperatures and under a broader range of reaction conditions.

Electrocatalytic [FeFe]-hydrogenase mimics for the hydrogen evolution reaction (HER) generally suffer from low activity, high overpotential, aggregation, oxygen sensitivity, and low solubility in water. By using atom-transfer radical polymerization (ATRP), a new class of [FeFe]-metallopolymers with precise molar mass, defined composition, and low polydispersity, has been prepared. The synthetic methodology introduced here allows facile variation of polymer composition to optimize the [FeFe] solubility, activity, and long-term chemical and aerobic stability. Water soluble functional metallopolymers facilitate electrocatalytic hydrogen production in neutral water with loadings as low as 2 ppm and operate at rates an order of magnitude faster than hydrogenases (2.5×10 s ), and with low overpotential requirement. Furthermore, unlike the hydrogenases, these systems are insensitive to oxygen during catalysis, with turnover numbers on the order of 40 000 under both anaerobic and aerobic conditions.

We show here how differences in surface composition for monolayer (ML)-tethered pyridine (Py)-treated CdSe quantum dots (QDs) affect band edge energetics, as a function of QD diameter. We compare UV−vis spectroscopy of QD solutions and X-ray (XPS) and ultraviolet (UPS) photoelectron spectroscopy of QDs tethered to 1,6hexanedithiol-modified Au surfaces. Differences in QD surface composition are brought about by differences in solvent composition during displacement of the native, X-type octadecylphosphonate (ODP − ) ligands with Py and by differences in exposure to trace H 2 O and O 2 during QD processing. Prior to surface tethering, exchange of the ODP − ligands with Py ligands under ambient (A) conditions leads to some surface passivation of the QD and no appreciable reduction in the spectroscopically estimated QD diameter. QDs processed in completely inert (I) environments (O 2 and H 2 O below detection limits in the solvents, processing environments, and during analysis) undergo a small decrease in diameter during Py exchange and an increase in size dispersity. These simple differences in processing conditions lead to important differences in QD band edge energetics which will impact their use as photocatalysts and photovoltaic or light-emitting diode active layers. XPS characterization of Py-capped QD-tethered MLs, compared with freshly etched CdSe(0001) single-crystal surfaces, indicates that I QDs show a higher Se surface coverage relative to A QDs. For A QDs, we propose that trace H 2 O present during processing provides a proton source that facilitates ODP − desorption and replacement with charge-compensating HO − ligands, which inhibits subsequent changes in QD surface composition. UPS-derived size-quantized ionization potentials (IPs) and electron affinities (EAs) for I QDs, corrected for shifts in the local vacuum level, closely track the energetic shifts predicted by the effective mass approximation (EMA). The vacuum level-corrected IP/EA values for A QDs show sizeable deviations from the EMA. We also describe an approach for characterization of UPS data for these QD MLs, which greatly enhances the sensitivity to mid-gap states above the VBM (seen for I QDs which are slightly enriched in surface Se) and offers a general approach to all semiconductor materials with low density of states in the valence band region. This study confirms the influence of ligand modification and processing environment on QD surface composition, which in turn impacts the CdSe QD energy levels that are important to applications in photocatalysis and optoelectronic device platforms.

Reviewed herein is the development of novel polymer‐supported [2Fe‐2S] catalyst systems for electrocatalytic and photocatalytic hydrogen evolution reactions. [FeFe] hydrogenases are the best known naturally occurring metalloenzymes for hydrogen generation, and small‐molecule, [2Fe‐2S]‐containing mimetics of the active site (H‐cluster) of these metalloenzymes have been synthesized for years. These small [2Fe‐2S] complexes have not yet reached the same capacity as that of enzymes for hydrogen production. Recently, modern polymer chemistry has been utilized to construct an outer coordination sphere around the [2Fe‐2S] clusters to provide site isolation, water solubility, and improved catalytic activity. In this review, the various macromolecular motifs and the catalytic properties of these polymer‐supported [2Fe‐2S] materials are surveyed. The most recent catalysts that incorporate a single [2Fe‐2S] complex, termed single‐site [2Fe‐2S] metallopolymers, exhibit superior activity for H2 production.

Electrocatalytic generation of H2 is challenging in neutral pH water, where high catalytic currents for the hydrogen evolution reaction (HER) are particularly sensitive to the proton source and solution characteristics. A tris(hydroxymethyl)aminomethane (TRIS) solution at pH 7 with a [2Fe-2S]-metallopolymer electrocatalyst gave catalytic current densities around two orders of magnitude greater than either a more conventional sodium phosphate solution or a potassium chloride (KCl) electrolyte solution. For a planar polycrystalline Pt disk electrode, a TRIS solution at pH 7 increased the catalytic current densities for H2 generation by 50 mA/cm2 at current densities over 100 mA/cm2 compared to a sodium phosphate solution. As a special feature of this study, TRIS is acting not only as the primary source of protons and the buffer of the pH, but the protonated TRIS ([TRIS-H]+) is also the sole cation of the electrolyte. A species that is simultaneously the proton source, buffer, and sole electrolyte is termed a protic buffer electrolyte (PBE). The structure–activity relationships of the TRIS PBE that increase the HER rate of the metallopolymer and platinum catalysts are discussed. These results suggest that appropriately designed PBEs can improve HER rates of any homogeneous or heterogeneous electrocatalyst system. General guidelines for selecting a PBE to improve the catalytic current density of HER systems are offered.

Small-molecule catalysts inspired by the active sites of [FeFe]-hydrogenase enzymes have long struggled to achieve fast rates of hydrogen evolution, long-term stability, water solubility, and oxygen compatibility. We profoundly improved on these deficiencies by grafting polymers from a metalloinitiator containing a [2Fe-2S] moiety to form water-soluble poly­(2-dimethylamino)­ethyl methacrylate metallopolymers (PDMAEMA-g-[2Fe-2S]) using atom transfer radical polymerization (ATRP). This study illustrates the critical role of the polymer composition in enhancing hydrogen evolution and aerobic stability by comparing the catalytic activity of PDMAEMA-g-[2Fe-2S] with a nonionic water-soluble metallopolymer based on poly­(oligo­(ethylene glycol) methacrylate) prepared via ATRP (POEGMA-g-[2Fe-2S]) with the same [2Fe-2S] metalloinitiator. Additionally, the tunability of catalyst activity is demonstrated by the synthesis of metallocopolymers incorporating the 2-(dimethylamino)­ethyl methacrylate (DMAEMA) and oligo­(ethylene glycol) methacrylate (OEGMA) monomers. Electrochemical investigations into these metallo­(co)­polymers show that PDMAEMA-g-[2Fe-2S] retains complete aerobic stability with catalytic current densities in excess of 20 mA·cm–2, while POEGMA-g-[2Fe-2S] fails to reach 1 mA·cm–2 current density even with the application of high overpotentials (η > 0.8 V) and loses all activity in the presence of oxygen. Random copolymers of the two monomers polymerized with the same [2Fe-2S] initiator showed intermediate activity in terms of current density, overpotential, and aerobic stability.

Ocular applications of polymeric materials have been widely investigated for medical diagnostics, treatment, and vision improvement. The human eye is a vital organ that connects us to the outside world so when the eye is injured, infected, or impaired, it needs immediate medical treatment to maintain clear vision and quality of life. Moreover, several essential parts of the eye lose their functions upon aging, causing diminished vision. Modern polymer science and polymeric materials offer various alternatives, such as corneal and scleral implants, artificial ocular lenses, and vitreous substitutes, to replace the damaged parts of the eye. In addition to the use of polymers for medical treatment, polymeric contact lenses can provide not only vision correction, but they can also be used as wearable electronics. In this Review, we highlight the evolution of polymeric materials for specific ocular applications such as intraocular lenses and current state-of-the-art polymeric systems with unique properties for contact lens, corneal, scleral, and vitreous body applications. We organize this Review paper by following the path of light as it travels through the eye. Starting from the outside of the eye (contact lenses), we move onto the eye’s surface (cornea and sclera) and conclude with intraocular applications (intraocular lens and vitreous body) of mostly synthetic polymers and several biopolymers. Initially, we briefly describe the anatomy and physiology of the eye as a reminder of the eye parts and their functions. The rest of the Review provides an overview of recent advancements in next-generation contact lenses and contact lens sensors, corneal and scleral implants, solid and injectable intraocular lenses, and artificial vitreous body. Current limitations for future improvements are also briefly discussed.

Polymer chemistry is essential within chemical education because of its applications in academic and industrial research, materials science, and across engineering disciplines. Teaching polymer chemistry principles early on in the undergraduate curriculum allows students to find connections between chemistry and real-world applications and can promote interest in science and scientific research. Performing laboratory experiments on polymers is of equal importance when integrating polymer concepts into undergraduate-level lectures. There are several widely utilized lab demonstrations on polymer synthesis, characterization, and applications, yet more, easy-to-handle experiments are needed that connect polymers to organic reactions, spectroscopy, and sustainability, especially in a virtual setting. This virtual experiment was designed to incorporate the synthesis of high sulfur-content polymers into the general chemistry laboratory during the pandemic. Teaching assistants (TAs) performed the experiments and collected the necessary data and observations for students. Video recordings of the polymerization reactions, reaction times, and collages of digital images depicting reaction progress (viscosity and color changes) are provided to students. During a single 2−3-h virtual lab meeting, students watch the lab videos, read the student handout and a research paper, and discuss the results and observations with their peers and lab TAs. The lab experiment demonstrates the interdependence of general chemistry learning objectives including chemical bonding, radicals, reaction kinetics, thermodynamics, stoichiometric calculations, and spectroscopy. In addition, this virtual experiment introduces undergraduate students to polymer chemistry, encourages them to look beyond the textbooks and lecture resources by using literature articles, and connects general chemistry concepts with upper-level chemistry classes. Postlab survey results show that students find the video recordings and group discussions on the polymerization reactions very helpful in understanding a new concept within a virtual distant-learning environment.