Royal Society of Chemistry Journal
We report on low molar mass cationic RAFT agents that provide predictable molar mass and low molar mass dispersities (Đm) in ab initio emulsion polymerization. Thus RAFT emulsion polymerization of styrene in the presence of the protonated RAFT agent, ((((cyanomethyl)thio)carbonothioyl)(methyl)amino)pyridin-1-ium toluenesulfonate (4), and the analogous methyl-quaternized RAFT agents, 4-((((cyanomethyl)thio)carbonothioyl)(methyl)amino)-1-methylpyridin-1-ium dodecyl sulfate (6), provide low dispersity polystyrene with Đm 1.2–1.4 for Mn ∼ 20 000. We postulate that the success of ab initio emulsion polymerization with 4 is due to the hydrophilicity of the pyridinium group, which is such that the water soluble RAFT agent partitions predominantly into the aqueous phase under the conditions of the experiment and that 4 provides little retardation. With 6, when the counterion is dodecyl sulfate, we can achieve “surfactant-free” RAFT emulsion polymerization to provide a low Đm polystyrene. However, the RAFT end-group is lost on isolation of the polymer. Preliminary results show that this class of RAFT agent is broadly applicable in ab initio emulsion polymerization of other more-activated monomers (e.g., butyl acrylate, butyl methacrylate). Furthermore, cyanomethyl(pyridin-4-yl)carbamodithioate (3, the RAFT agent in neutral form) provides molar mass control and Đm < 1.8 in ab initio emulsion polymerization of less activated monomers, specifically, the vinyl esters, vinyl acetate and vinyl benzoate.
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Advances in Polymer Technology Journal
Poly(methyl methacrylate-block-styrene) block copolymers (BCs) of low dispersity were selectively sulfonated on the styrenic segment. Several combinations of degree of polymerization and volume fraction of each block were investigated to access different self-assembled morphologies. Thin films of the sulfonated block copolymers were prepared by spin-coating and exposed to solvent vapor (SVA) or thermal annealing (TA) to reach equilibrium morphologies. Atomic force microscopy (AFM) was employed for characterizing the films, which exhibited a variety of nanometric equilibrium and nonequilibrium morphologies. Highly sulfonated samples revealed the formation of a honeycomb-like morphology obtained in solution rather than by the self-assembly of the BC in the solid state. The described morphologies may be employed in applications such as templates for nanomanufacturing and as cover and binder of catalytic particles in fuel cells.
CM Chemistry of Materials Journal
A structurally diverse family of 39 covalent triazine-based framework materials (CTFs) is synthesized by Suzuki-Miyaura polycondensation and tested as hydrogen evolution photocatalysts using a high-throughput workflow. The two best-performing CTFs are based on benzonitrile and dibenzo[b,d]thiophene sulfone linkers, respectively, with catalytic activities that are among the highest for this material class. The activities of the different CTFs are rationalized in terms of four variables: the predicted electron affinity, the predicted ionization potential, the optical gap, and the dispersibility of the CTFs particles in solution, as measured by optical transmittance. The electron affinity and dispersibility in solution are the best predictors of photocatalytic hydrogen evolution activity.
Pure and Applied Chemistry Journal
Carbohydrate structures are often complex. Unfortunately, synthesis of the range of sugar combinations precludes the use of a single coupling protocol or set of reagents. Adapting known, reliable bench-chemistry reactions to work via automation will help forward the goal of synthesizing a broad range of glycans. Herein, the preparation of di- and tri-saccharides of alpha 1→2 rhamnan fragments is demonstrated using thioglycoside donors with the development for a solution-phase-based automation platform of commonly used activation conditions using N-iodosuccinimide (NIS) with trimethylsilyl triflate. Byproducts of the glycosylation reaction are shown to be compatible with hydrazine-based deprotection conditions, lending broader functionality to this method as only one fluorous-solid-phase extraction step per coupling/deprotection cycle is required.
September 2019 – Agrate Brianza, Italy / Füllinsdorf, Switzerland
The Italian Group Intercos, a global leader in color cosmetics, has decided to partner with Chemspeed Technologies to accelerate and enhance the research of novel cosmetic formulations and the corresponding color development and prototyping.
Cosmetic formulations are quickly growing in complexity: changing ingredient regulations, increased environmental awareness, evolving cosmetic trends and curiosity for new color matches are just a few of the drivers giving a hard time to scientists.
Automation and digitalization methodologies represent a revolutionary approach to widely explore ingredient and process variables and accelerate the development of new products. Chemspeed’s formulation workstation, called “FORMAX”, is the first fully automated and integrated formulation and characterization solution for the personal care industry. A large number of automated formulations (from 3 to 36 depending on configuration) can be prepared contemporaneously while screening several parameters: ingredients, concentrations, amounts, color to matrix ratio, temperature, pH, viscosity and much more.
FORMAX key to success include precise gravimetric dispensing of ingredients (including solids and highly-viscous liquids), preparation of phases at different mixing speeds and temperatures (including ingredient addition while stirring/heating), formulation characterization (viscosity, pH, …) at any time during the experiment, ready to use samples for testing, color prototyping, etc. The experimental results (successes and failures) are used to rank each formulation and make it repeatable at any time. After this ranking, a set of new conditions can be generated and run experimentally using FORMAX. This process can continue until the best product or color is identified.
Intercos scientists mentioned: “Lamination is performed directly in the formulation vessel. This avoids messy and time-consuming color preparation steps and enables color adjustments at any time. This, together with the contemporaneous formulation of multiple recipes per cycle, grants a much shorter time to sample.”
High-throughput methodologies represent an effective approach to accelerate battery development. With an almost unlimited range of raw material and process variables to evaluate, very short time-to market milestones and incumbent technologies in the view, scientists in battery research manage to stay ahead of the curve thanks to Chemspeed’s innovative solutions.
Organic molecules tend to close pack to form dense structures when they are crystallized from organic solvents. Porous molecular crystals defy this rule: they typically crystallize with lattice solvent in the interconnected pores. However, the design and discovery of such structures is often challenging and time consuming, in part because it is difficult to predict solvent effects on crystallization. Here, we combine crystal structure prediction (CSP) with a high-throughput crystallization screening method to accelerate the discovery of stable hydrogen-bonded frameworks. We exemplify this strategy by finding new phases of two well-studied molecules in a computationally targeted way. Specifically, we find a new porous polymorph of trimesic acid, δ-TMA, that has a guest free hexagonal pore structure, as well as three new solvent-stabilized diamondoid frameworks of adamantane-1,3,5,7-tetracarboxylic acid (ADTA).
Chemical Engineering Journal
The hot injection technique for the synthesis of quantum dots (QDs) is a well-established and widely used method in the lab. However, scale-up rules do not exist. One reason is that in particular the role of process parameters like mixing on particle formation is largely unknown, as systematic examination of the latter is impossible for the laborious and complex manual synthesis. Herein we studied the mixing induced self-focusing of particle size distributions (PSDs) of CdSe QDs using automation in combination with a deﬁned stirrer geometry. Basis for our study is a platform that allows parallelization with inline temperature monitoring, deﬁned injection rate, accurate sampling times as well as controlled stirring. Reproducibility in terms of optical product properties was analyzed by absorption and emission whereas reproducibility in terms of the PSD was veriﬁed by deconvolution of UV/Vis absorbance spectra and especially by analytical ultracentrifugation (AUC) complemented by transmission electron microscopy (TEM). In line with previous results, AUC conﬁrmed that even QDs made by hot injection in an automated setup are polydisperse with multimodal size distributions. Finally, reproducibility in combination with early stage sampling and controlled mixing allowed us for the ﬁrst time to analyze the inﬂuence of stirring on focusing and defocusing of PSDs, that has been expressed in terms of the evolution of the relative standard deviation (RSD). Our work paves the way to gain in-depth understanding of often forgotten process-structure relationships of colloidal nanoparticles which eventually is a ﬁrst step in the direction of the development of scalable synthesis and reliable application of high-quality QDs in technical applications.
Organic Process Research & Development Journal
High-throughput experimentation is a technique for screening multiple reaction conditions in parallel at micro or nanoscale without depleting precious starting materials. However, assembling a comprehensive screening set often involves the distribution of large number of solid reagents with diverse physical properties in small quantities. Automated solid dispensing, especially at submilligram scale, has long been a challenge with no practical and reliable solutions. This paper describes the use of our newly developed chemical-coated beads technology to provide a universal approach to the solid handling problem. This technology, when combined with an automated solid dispensing platform or calibrated scoops, can dispense submilligram quantities of a variety of solids with eﬃciency and adequate accuracy.