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Ring opening polymerization (ROP) of N-carboxy anhydride (NCA) amino acids presents a rapid way to synthesize high molecular weight polypeptides with different amino acid compositions. The compositional and functional versatility of polypeptides make these materials an attractive choice for biomaterials. The functional performance of polypeptide materials is equally linked to their conformation which is determined by the amino acid sequence in the polymer chains. Here, the interplay between composition and conformation of synthetic polypeptides obtained by NCA polymerization was explored. Various copolypeptides from Glu(Bzl) and Ser(Bzl) were prepared to investigate how polypeptide composition affected the conformation of the resulting copolymer. Polymerization kinetics indicated that the copolymerization of Glu(Bzl) and Ser(Bzl) preferentially yielded alternating copolymers. Both the polydispersity and the conformation of the polypeptides were dependent on the Ser(Bzl) content in the polymer, demonstrating that polypeptide functionalities could be tuned directly by altering the relative amounts of amino acids in the chain. This work presents the first step toward an improved understanding and control over polypeptide conformation through modulating the amino acid composition of the material. Understanding this sequence–functionality relationship is essential to advancing the use of ROP as a technique to design smart polypeptide based materials with specific functions. © 2016 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2331–2336

© 2019 The Royal Society of Chemistry. Biological X-ray fluorescence microscopy (XFM) is an important tool for determining quantitative distributions of bioinorganics and essential trace elements. Here we present a new analysis approach for rapid nanoscale ptychographic imaging and simultaneous chemical mapping of large radiation sensitive specimens without image degradation associated with probe evolution.

Homo- and copolymers of di(ethylene glycol) methyl ether methacrylate (DEGMA) and oligo(ethyleneglycol) methyl ether methacrylate (OEGMA1100) were synthesized with various chain lengths via reversible addition fragmentation chain transfer (RAFT) polymerization in ethanol using (M)/(RAFT) ratios of 100 and 200. Kinetic investigations on the homo- and copolymerization of these monomers were performed using a parallel synthesizer resulting in well-defined polymers with poly- dispersity indices mostly below 1.3. The polymerization kinetics are presented and discussed in detail surprisingly revealing that the DEGMA homopolymerization is slower than the OEGMA1100 homopolymerization. Transfer coefficients c app were esti- mated to be � 0.5 for the RAFT polymerization of both DEGMA and OEGMA1100 resulting in hybrid behavior at the beginning of the polymerizations. Subsequent copolymerization also revealed fast incorporation of the OEGMA1100 and relatively slow incorporation of DEGMA resulting in well-defined copolymers with a molecular weight up to 100 kDa and polydispersities around 1.20. V C 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2811-2820, 2009

The click reaction of azido- and ethynyl-functionalized terpyridines has been exploited to obtain a series of 1H-1,2,3-triaz- ole-substituted terpyridines. This protocol was extended towards the synthesis of terpyridine-based macroligands via end group mod- ification of ethynyl-functionalized polymers. Finally, the combina- tion of two orthogonal terpyridines within one click reaction highlights the potential of this approach with respect to the prepara- tion of new building blocks for supramolecular assemblies and functional materials.

The nitroxide-mediated copolymerization of 2-hydroxypropyl acrylate (HPA) with N-acryloylmorpholine (Amor) or N,N-dimethylacrylamide (DMA) was investigated using N-tert-butyl-N-(1?-diethylphosphono-2,2?- dimethylpropyl)-O-(2-carboxyl-prop-2-yl) (BlocBuilder) alkoxyamine initiator and additional free nitroxide (SG-1). Different reaction conditions, such as the concentration of additional SG-1, were tested to optimize the homopolymerizations using a Chemspeed ASW2000 automated parallel synthesizer. Best control for the homopolymerizations (polydispersity indices of 1.2-1.3) of all three monomers was achieved using 20% additional SG-1 (relative to the initiator) at a reaction temperature of 110ÝC for 2 M solutions in N,N-dimethylformamide and a monomer/initiator ratio of 100/1. Libraries of P(Amor-stat-HPA) and P(DMA-stat-HPA) were synthesized with 0-100 mol % HPA with 10 mol % increments using the optimized conditions obtained for the homopolymerizations. The resulting polymers had narrow molecular weight distributions, and their compositions, determined using 1H NMR spectroscopy and elemental analysis, were close to the theoretical compositions. In addition, all copolymers of both libraries had single glass transition temperatures (Tg), and the transition temperatures decreased from the Tg of P(Amor) (147ÝC) and P(DMA) (111ÝC) to the T g of P(HPA) (22ÝC) with increasing HPA content. The cloud point of P(HPA) showed concentration dependence as well as a concentration dependent hysteresis. The cloud points of aqueous solutions of the copolymer libraries could be tuned from 21.4 to 88.0ÝC and to 82.9ÝC for P(Amor-stat-HPA) and P(DMA-stat-HPA), respectively, at a concentration of 1 wt %. LCST behavior was observed for copolymers with >40 wt % HPA in P(Amor-stat-HPA) and >55 wt % HPA in the P(DMA-stat-HPA) library. © 2008 American Chemical Society

The aim of this research was to study the effect of the initiator on the resulting monomer distribution for the cationic ring-opening copolymerization of 2-ethyl-2-oxazoline (EtOx) and 2-phenyl-2-oxazoline (PhOx). At first, kinetic studies were performed for the homopolymerizations of both monomers at 160 ÝC under microwave irradiation using four initiators. These initiators have the same benzylinitiating group but different leaving groups, Cl-, Br-, I-, and OTs-. The basicity of the leaving group affects the ratio of covalent and cationic propagating species and, thus, the polymerization rate. The observed differences in polymerization rates could be correlated to the concentration of cationic species in the polymerization mixture as determined by 1H NMR spectroscopy. In a next-step, polymerization kinetics were determined for the copolymerizations of EtOx and PhOx with these four initiators. The reactivity ratios for these copolymerizations were calculated from the polymerization rates obtained for the copolymerizations. This approach allows more accurate determination of the copolymerization parameters compared to conventional methods using the composition of single polymers. When benzyl chloride (BCl) was used as an initiator, no copolymers could be obtained because its reactivity is too low for the polymerization of PhOx. With decreasing basicity of the used counterions (Br- > I- > OTs-), the reactivity ratios gradually changed from rEtOx = 10.1 and rPhOx = 0.30 to rEtOx = 7.9 and rPhOx = 0.18. However, the large difference in reactivity ratios will lead to the formation of quasi-diblock copolymers in all cases. In conclusion, the used initiator does influence the monomer distribution in the copolymers, but for the investigated system the differences were so small that no difference in the resulting polymer properties is expected. © 2008 Wiley Periodicals, Inc

Poly(acrylate)s as well as poly(methacrylate)s were successfully synthe- sized via reversible addition-fragmentation chain-transfer (RAFT) polymerizations using 2-cyano-2-butyl dithiobenzoate (CBDB) as RAFT-agent. Four different ratios of RAFT to initiator were screened for four acrylates and four methacrylates using auto- mated parallel synthesizer robots. The reactions were monitored by gel permeation chromatography (GPC) and gas chromatography (GC). The knowledge obtained dur- ing this screening was used for the designed synthesis of block and random copoly- mers containing a water- and a non water-soluble monomer. The results obtained from GPC analysis together with 1 H NMR spectroscopy demonstrate the possibility to design and prepare well-defined block and random copolymers. V C 2005 Wiley Periodi

High-throughput experimentation (HTE) was successfully applied in atom transfer radical polymn. (ATRP) of Me methacrylate (MMA) for the rapid screening and optimization of different reaction conditions. A library of 108 different reactions was designed for this purpose, which used four different initiators [ethyl 2-bromoisobutyrate, Me 2-bromopropionate, (1-bromoethyl)benzene, and p-toluenesulfonyl chloride], five metal salts (CuBr, CuCl, CuSCN, FeBr2, and FeCl2), and nine ligands (2,2'-bipyridine and its derivs.). The optimal reaction conditions for Cu(I) halide, CuSCN, and Fe(II) halide-mediated ATRP systems with 2,2'-bipyridine and its 4,4'-dialkyl-substituted derivs. as ligands were detd. Cu(I)-mediated systems were better controlled than Fe(II)-mediated ones under the examd. conditions. A bipyridine-type ligand with a crit. length of the substituted alkyl group (i.e., 4,4'-dihexyl 2,2'-bipyridine) exhibited the best performance in Cu(I)-mediated systems, and p-toluenesulfonyl chloride and Et 2-bromoisobutyrate could effectively initiate Cu(I)-mediated ATRP of MMA, resulting in polymers with low polydispersities in most cases. Besides, Cu(I) halide-mediated ATRP with 4,5'-dimethyl 2,2'-bipyridine as the ligand and p-toluenesulfonyl chloride as the initiator proved to be better controlled than those with 4,4'-dimethyl 2,2'-bipyridine as the ligand, and polymers with much lower polydispersities were obtained in the former cases. This successful HTE example opens up a way to significantly accelerate the development of new catalytic systems for ATRP and to improve the understanding of structure-property relationships of the reaction systems

The systematical kinetic investigations of four 2-substituted-2-oxazoline monomers with four initiators at two temperatures and four monomer/initiator ratios are described. To cover this broad range of variables (128 different combinations), an automated synthesizer was used to accelerate the investigations and to provide highly comparable results. With both gas chromatography and gel permeation chromatogra- phy, the livingness and the polymerization rates were determined for the different polymerizations. The resulting insights in the kinetics were used for the directed synthesis of truly random copolymers and copolymers with composition drift. © 2004

The temperature dependency of the polymerization of 2-phenyl-2-oxazoline was investigated utilizing a commercially available automated synthesizer equipped with individually heatable reactors. Kinetic investigations resulted in an optimal polymerization temperature and activation energy determination for the polymerizations initiated with methyl tosylate. Moreover, the in situ generation of benzyl iodide (more reactive initiator) from benzyl chloride and sodium iodide is described, whereby solid sodium iodide was automatically dosed into the reactors.

Summary: Automated parallel synthesis and high-throughput screening has been proven to drastically speed up polymer and materials research. Here we present an automated parallel approach for investigation of the influences of different counter ions (chloride, bromide, acetate and sulfate) on the iron(II) mediated metallo-supramolecular polymerization of bis(2,2′:6′,2″-terpyrid-4′-yl)-poly(ethylene oxide)179. The synthesized polymers were characterized by 1H NMR, UV-vis and IR. The degree of polymerization has been estimated on the basis of concentration dependent viscosity measurements. The conversion as well as the degree of polymerization followed the order: bromide, chloride > sulfate ≫ acetate.

Gel permeation chromatography (GPC) and gas chromatography (GC) were successfully introduced into a high-throughput workflow. The feasibility and limitations of online GPC with a high-speed column was evaluated by measuring polystyrene standards and comparison of the results with regular offline GPC measurements. The reliability of the online GC characterization was investigated by monitoring the cationic ring-opening-polymerization of 2-ethyl-2-oxazoline, whose polymerization kinetics were determined by both online and offline GC.

The application of automated parallel synthesizer robots for the investigation of polymn. processes is of major interest at present. In this contribution we describe the application of the emulsion polymn. of styrene and vinyl acetate. The prepns. of emulsion and latexes were investigated in detail and compared to \"conventional\" stirred tank reactors. In particular the influence of the vortex mixing as well as the limitations regarding solid content and reactor fouling are addressed. [on SciFinder (R)]

Combinatorial chemistry and high-throughput experimentation have drawn great attention in recent years because of their significant advantages in increasing the research productivity. One of the emerging fields is their application in polymer science. Herein we describe the high-throughput optimization of purification conditions for polymers prepared via atom transfer radical polymerization using an automated synthesizer. The effects of the column materials, column lengths and eluent volumes on the purification efficiency as well as the molecular weights of the obtained purified polymers were systematically investigated for the first time. The optimum purification conditions for the removal of copper catalysts are provided. As a result an online high-throughput purification workflow using SPE cartridges is now available for the utilization in automated parallel synthesizers for ATRP screening experiment.

Living cationic ring-opening polymerizations of 2-ethyl-2-oxazoline and purification of the resulting polymers were performed utilizing an automated synthesizer. Eight polymers (500 mg scale) as well as 40 polymers (150 mg scale) were synthesized in parallel to investigate the reproducibility and the living character of the polymerizations. The poly(2-ethyl-2-oxazoline)s obtained such were characterized by means of 1 H NMR spectroscopy, MALDI-TOF mass spectrometry and online gel permeation chromatography.

A parallel synthetic approach toward homogeneous atom-transfer radical polymerization of methyl methacrylate has been successfully applied by utilizing an automated synthesizer. Experimental set-up, automated parallel synthesis and purification of the polymers via a solid-phase extraction set-up, as well as online and offline measurements of the molecular weights and monomer conversion are described in detail. In addition, a comparison with conventional experiments in the laboratory is provided.

Poly(methyl methacrylate)s were successfully synthesized in a controlled fashion via reversible addition-fragmentation chain transfer polymerizations utilizing an automated synthesizer. Sixteen polymers were synthesized in a parallel way utiliz- ing the Chemspeed Accelerator TM SLT100 to investigate the reproducibility and the control over the polymerizations. The obtained polymers were characterized by gel permeation chromatography (GPC) and automated MALDI TOFMS measurements, thereby proving the reproducibility and controllability of the investigated automated setup. Furthermore, temperature optimization reactions were performed utilizing an individually heatable reactor block. Moreover, to demonstrate the presence of active polymer chains in the reaction mixture, chain extension polymerizations were per- formed on the automated synthesizer. The results obtained from these chain extension experiments demonstrate the possibility to design well-defined A-b-B block copolymers with different monomers as building units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5775-5783, 2004

The monomer concentration for the cationic ring-opening polymerization of 2-ethyl-2-oxazoline in N,N-dimethylacetamide was optimized utilizing high-throughput experimentation methods. Detailed 1H-NMR spectroscopic investigations were performed to understand the mechanistic aspects of the observed concentration effects. Finally, the improved polymerization concentration was applied for the synthesis of higher molecular weight (> 10,000 Da) poly(2-ethyl-2-oxazoline)s. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1487–1497, 2005