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MaDDOSY (Mass Determination Diffusion Ordered Spectroscopy) using an 80 MHz Bench Top NMR for the Rapid Determination of Polymer and Macromolecular Molecular Weight. Macromol Rapid Commun 2024; 45:e2300692. [PMID: 38288674 DOI: 10.1002/marc.202300692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/12/2024] [Indexed: 02/13/2024]
Abstract
Measurement of molecular weight is an integral part of macromolecular and polymer characterization which usually has limitations. Herein, this article presents the use of a bench-top 80 MHz Nuclear Magnetic Resonance (NMR) spectrometer for diffusion-ordered spectroscopy as a practical and rapid approach for the determination of molecular weight/size using a novel solvent and polymer-independent universal calibration.
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2
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Lewis acid catalysed polymerisation of cyclopentenone. Chem Sci 2024; 15:639-643. [PMID: 38179536 PMCID: PMC10762972 DOI: 10.1039/d3sc05186b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 11/30/2023] [Indexed: 01/06/2024] Open
Abstract
A modest structural change of a β-diketiminate-supported aluminium complex leads to dramatic differences in the reactivity towards cyclopentenone. While the bulkier complex efficiently executes Diels Alder transformations the smaller analogue performs unique polymerisation of this substrate. This observation appears to be unprecedented in the chemistry of Lewis acids and cyclic dienophiles as it represents a unique way to polymerise a functionalised olefin.
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3
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High Throughput Multidimensional Kinetic Screening in Continuous Flow Reactors. Angew Chem Int Ed Engl 2023; 62:e202308838. [PMID: 37537139 DOI: 10.1002/anie.202308838] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/03/2023] [Accepted: 08/03/2023] [Indexed: 08/05/2023]
Abstract
An automated high throughput multidimensional reaction screening platform based on an inline Fourier-transform infrared spectroscopy is presented. By combining flow chemistry, machine automation and inline analysis, the platform is able to screen reactions in multidimensions (residence time, monomer concentration, degree of polymerization, reaction temperature and monomer conversion) rapidly and efficiently way. Kinetic data libraries associated with high data precision (absolute error <4 %), high reproducibility and high data density are built with ease from the platform. To test the method, we screened the reversible addition-fragmentation chain transfer polymerization of methyl acrylate in unmatched detail, and the ring opening metathesis polymerization of methyl-5-norbornene-2-carboxylate. The method we introduce is a key step in providing "big data" for data driven research in the future, and already at present allows for precise prediction of reaction outcomes within the high-dimensional chemical parameter space that is screened.
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4
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Process intensification of continuous-flow seATRP by a sonicated multi-reactor setup. REACT CHEM ENG 2023; 8:2170-2176. [PMID: 38014415 PMCID: PMC10443438 DOI: 10.1039/d3re00235g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 05/31/2023] [Indexed: 11/29/2023]
Abstract
Simplified electrochemically mediated atom transfer radical polymerization (seATRP) is a versatile technique for synthesizing polymers with precise control and complex architecture. Continuous-flow seATRP has recently been realized by using a sonicated microreactor but still faces limitations such as relatively low conversion and difficulties in synthesizing polymers with high molecular weight. Herein, a novel multi-reactor setup is demonstrated. By tuning the currents applied to different reaction stages in the setup, 90% conversion can be achieved while maintaining relatively low dispersity (<1.35). Meanwhile, the unique design enables a wider processing window for sonication due to greater viscous attenuation in the second reactor, thus largely addressing the problem associated with high viscosity during the synthesis of high molecular weight polymers. The developed setup also offers an alternative strategy for future scale-up of continuous-flow seATRP.
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5
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From monomer to micelle: a facile approach to the multi-step synthesis of block copolymers via inline purification. Chem Sci 2023; 14:8466-8473. [PMID: 37592997 PMCID: PMC10430632 DOI: 10.1039/d3sc01819a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/06/2023] [Indexed: 08/19/2023] Open
Abstract
A one-pass continuous flow strategy to form block copolymer nanoaggregates directly from monomers is presented. A key development towards such a sophisticated continuous flow setup is a significant improvement in continuous flow dialysis. Often impurities or solvent residues from polymerizations must be removed before block extensions or nanoaggregate formation can be carried out, typically disrupting the workflow. Hence, inline purification systems are required for fully continuous operation and eventual high throughput operation. An inline dialysis purification system is developed and exemplified for amphiphilic block copolymer synthesis from thermal and photoiniferter reversible addition fragmentation chain transfer (RAFT) polymerization. The inline dialysis system is found to be significantly faster than conventional batch dialysis and the kinetics are found to be very predictable with a diffusion velocity coefficient of 4.1 × 10-4 s-1. This is at least 4-5 times faster than conventional dialysis. Moreover, the newly developed setup uses only 57 mL of solvent for purification per gram of polymer, again reducing the required amount by almost an order of magnitude compared to conventional methods. Methyl methacrylate (MMA) or butyl acrylate (BA) was polymerized in a traditional flow reactor as the first block via RAFT polymerization, followed by a 'dialysis loop', which contains a custom-built inline dialysis device. Clearance of residual monomers is monitored via in-line NMR. The purified reaction mixture can then be chain extended in a second reactor stage to obtain block copolymers using poly(ethylene glycol) methyl ether acrylate (PEGMEA) as the second monomer. In the last step, nano-objects are created, again from flow processes. The process is highly tuneable, showing for the chosen model system a variation in nanoaggregate size from 34 nm to 188 nm.
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6
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Photoresponsive Emulsion-Templated Porous Materials via Orthogonal Photoclick Chemistry. ACS APPLIED MATERIALS & INTERFACES 2023; 15:11141-11149. [PMID: 36799738 DOI: 10.1021/acsami.2c22546] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The functionalization of emulsion-templated porous polymers (polyHIPEs) utilizing modern and efficient chemistries is an important avenue for tailoring the properties of these scaffolds for specific and specialized applications. Herein, tetrazole photoclick chemistry is utilized for the efficient functionalization of polyHIPEs synthesized from various monomer systems and polymerization chemistries. Using both radical polymerization and thiol-ene polymerization, polyHIPEs with well-defined, interconnected open-cell morphologies are synthesized with tetrazole concentrations ranging from 0 to 5 w/v %, with the pore diameters ranging from 3 to 24 μm. Analyzed by fluorescence spectroscopy, FTIR spectroscopy, and confocal microscopy, spatially controlled functionalization to generate photopatterned fluorescent polyHIPEs is demonstrated via the reaction with residual acrylate and thiol groups. In addition, the scaffolds can be readily functionalized with external dipolarophiles such as acrylates to incorporate a functionality onto the polyHIPE surface. With many functional tetrazoles also reported in the literature, a PEG-tetrazole is also used to explore the photoinduced functionalization of polyHIPEs possessing tunable ratios of thiol and acrylate groups, and the effect on fluorescence, wettability, and biocompatibility is analyzed. Overall, the reaction is shown to be a broadly applicable tool for polyHIPE functionalization with many avenues for further development toward specific applications.
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7
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A Predictive Machine-Learning Model for Propagation Rate Coefficients in Radical Polymerization. Polym Chem 2023. [DOI: 10.1039/d2py01531e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Using a log-log regression, the propagation rate coefficients for radical polymerization are correlated with basic molecular properties. These are either available from literature, or from simple and non-time-consuming calculations. Parameters...
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8
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Narrowing Down Chain Length Effects on the Antibacterial Action of Guanylated Oligomers. Polym Chem 2023. [DOI: 10.1039/d3py00203a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2023]
Abstract
Synthesis of monodisperse guanylated oligomers through reversible addition fragmentation chain transfer (RAFT) polymerization of 2-boc aminoethyl acrylate followed by flash chromatography is described. To achieve antimicrobial action, the RAFT-derived protected...
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9
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Synthesis of electrically conducting nanocomposites via Pickering miniemulsion polymerization: Effect of graphene oxide functionalized with different capping agents. Eur Polym J 2022. [DOI: 10.1016/j.eurpolymj.2022.111498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Solvent‐Independent Molecular Weight Determination of Polymers Based on a Truly Universal Calibration. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202114536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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11
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Pulsed Laser Polymerization – Size Exclusion Chromatography Investigations into Backbiting in Ethylhexyl Acrylate Polymerization. Polym Chem 2022. [DOI: 10.1039/d1py01533h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Free radical acrylate polymerization is associated with a considerable number of side reactions occurring during chain growth. Most notably, the secondary chain propagating radicals can undergo intramolecular transfer reactions, forming...
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12
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One-Pot Multifunctional Polyesters by Continuous Flow Organocatalysed Ring-Opening Polymerisation for Targeted and Tunable Materials Design. Polym Chem 2022. [DOI: 10.1039/d2py00088a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Targeted and tunable access to biodegradable polymers will be vital for their continued adoption and use in modern materials applications. Herein we report a platform for the synthesis of well-defined,...
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Continuous-Flow Self-Supported seATRP Using a Sonicated Microreactor. Chem Sci 2022; 13:12326-12331. [PMID: 36349267 PMCID: PMC9628926 DOI: 10.1039/d2sc03608h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 09/23/2022] [Indexed: 11/23/2022] Open
Abstract
Continuous-flow simplified electrochemically mediated atom transfer radical polymerization (seATRP) was achieved for the first time without supporting electrolytes (self-supported) using a novel sonicated tubular microreactor. Polymerizations of different acrylic monomers were carried out under different applied currents. The reaction was fast with 75% conversion achieved at ambient temperature in less than 27 minutes. Results also showed good evolution of molecular weight and maintained narrow molecular weight distribution. The reaction rate can be further manipulated by tuning the applied current. Sonication under proper conditions was found to be able to significantly improve both reaction rate and controllability. Self-supported reactions also enable more environmentally friendly and cost-effective operations. Continuous-flow self-supported seATRP was realized for the first time using a novel sonicated microreactor. This provides an alternative route to scale up the eATRP process and an opportunity for a more environmentally friendly synthesis.![]()
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Abstract
The influence of dispersity in the molecular weight distributions in the core forming block for block copolymer (BCP) self-assembly is analyzed via an automated flow synthesis approach. Polystyrenes with increasing...
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15
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Abstract
Antoine Buchard and Tanja Junkers introduce the Polymer Chemistry themed collection on Sustainable Polymers.
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16
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Amphiphilic Conjugated Block Copolymers as NIR-Bioimaging Probes
. Polym Chem 2022. [DOI: 10.1039/d2py00258b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Altough semiconductiong polymer nanoparticles (SPN) are emerging as versatile theragnostic platforms for drug delivery and near infrared (NIR)-imaging, their synthesis remains restricted to nanoprecipatation or graft polymers. In here we present a...
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Abstract
We present an updated and expanded dataset of benchmark propagation rate coefficient (kp) data obtained from pulsed laser polymerization (PLP) of 13 vinyl monomers (styrene, methyl methacrylate, ethyl methacrylate, butyl...
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Solvent-Independent Molecular Weight Determination of Polymers Based on a Truly Universal Calibration. Angew Chem Int Ed Engl 2021; 61:e202114536. [PMID: 34861091 DOI: 10.1002/anie.202114536] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Indexed: 01/16/2023]
Abstract
Diffusion-ordered NMR spectroscopy (DOSY) allows for accurate molecular weight calibration and determination that can be corrected for solvent influences. Polystyrene and poly(ethylene glycol) standards have been used to calibrate DOSY diffusion data for a variety of solvents, showing a high correlation of data when the bulk viscosity of the solvent is accounted for following the Stokes-Einstein equation. In this way, a type of universal calibration is introduced that allows for determinations of average molecular weight that are at least as accurate as those of traditional size-exclusion chromatography (SEC), if not better. Further, we demonstrate that DOSY calibrations can be used between laboratories, hence removing the need for individual calibration of setups as currently done.
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20
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Abstract
We introduce a straightforward and clean method to synthesize semiconducting triblockcopolymers (tri-BCPs) using RAFT polymerization.
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21
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The block copolymer shuffle in size exclusion chromatography: the intrinsic problem with using elugrams to determine chain extension success. Polym Chem 2021. [DOI: 10.1039/d1py00210d] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Is an increase in hydrodynamic volume always expected in block copolymer synthesis? Why SEC is sometimes not the last word.
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22
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Abstract
An online database created and curated by an IUPAC subcommittee is introduced.
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23
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PEGylating poly(p-phenylene vinylene)-based bioimaging nanoprobes. J Colloid Interface Sci 2021; 581:566-575. [PMID: 32818676 DOI: 10.1016/j.jcis.2020.07.145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 11/19/2022]
Abstract
HYPOTHESIS Conjugated polymer nanoparticles (CNPs) have attracted considerable attention within bioimaging due to their excellent optical properties and biocompatibility. However, unspecific adsorption of proteins hampers their effective use as advanced bioimaging probes. Controlled methodologies made possible tailor-made functional poly(p-phenylene vinylene), enabling one-pot synthesis of CNPs containing functional surface groups. Hence, it should be feasible to PEGylate these CNPs to tune the uptake by cell lines representative for the brain without imparting their optical properties. EXPERIMENTS CNPs consisting of the statistical copolymer 2-(5'-methoxycarbonylpentyloxy)-5-methoxy-1,4-phenylenevinylene and poly(2-methoxy-5-(3',7'-dimethoxyoctyloxy)-1,4-phenylenevinylene) were fabricated by miniemulsion solvent evaporation technique. Surface carboxylic acid groups were used to covalently attach amine-terminated polyethylene glycol (PEG) of different molecular weights. We investigated the effect of grafting CNPs with PEG chains on their intrinsic optical properties, protein adsorption behavior and uptake by representative brain cell lines. FINDINGS PEGylation did not affect the optical properties and biocompatibility of our CNPs. Moreover, a significant decrease in protein corona formation and unspecific uptake in central nervous system cell lines, depending on PEG chain length, was observed. This is the first report indicating that PEGylation does not affect the CNPs role as excellent bioimaging tools and can be adapted to tune biological interactions with brain cells.
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24
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Amino acid acrylamide mimics: creation of a consistent monomer library and characterization of their polymerization behaviour. Polym Chem 2021. [DOI: 10.1039/d1py00735a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel consistent approach to mimic the structure of biopolymers via precision polymer synthesis with reversible deactivation radical polymerization (RDRP).
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25
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26
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27
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29
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Accelerated Polypeptide Synthesis via
N
‐Carboxyanhydride Ring Opening Polymerization in Continuous Flow. Macromol Rapid Commun 2020; 41:e2000071. [DOI: 10.1002/marc.202000071] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 07/06/2020] [Indexed: 02/06/2023]
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30
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Photo-induced copper-mediated (meth)acrylate polymerization towards graphene oxide and reduced graphene oxide modification. Eur Polym J 2020. [DOI: 10.1016/j.eurpolymj.2020.109810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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31
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Designing molecular weight distributions of arbitrary shape with selectable average molecular weight and dispersity. Eur Polym J 2020. [DOI: 10.1016/j.eurpolymj.2020.109834] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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32
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Abstract
A method for encryption and safe transmission of data in the shape of molecular weight distributions (MWD) is presented.
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33
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Room temperature synthesis of block copolymer nano-objects with different morphologies via ultrasound initiated RAFT polymerization-induced self-assembly (sono-RAFT-PISA). Polym Chem 2020. [DOI: 10.1039/d0py00461h] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The first room temperature synthesis of diblock copolymer nano-objects with different morphologies using ultrasound (990 kHz) initiated reversible addition-fragmentation chain transfer PISA (sono-RAFT-PISA) in aqueous system.
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34
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Online tracing of molecular weight evolution during radical polymerization via high-resolution FlowNMR spectroscopy. Polym Chem 2020. [DOI: 10.1039/d0py00475h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-resolution FlowNMR was coupled to a continuous flow reactor to monitor polymer molecular weight evolution online by diffusion ordered NMR spectroscopy.
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35
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Flash-synthesis of low dispersity PPV via anionic polymerization in continuous flow reactors and block copolymer synthesis. Polym Chem 2020. [DOI: 10.1039/d0py01245a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Low dispersity poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)]-1,4-phenylenevinylene (MDMO-PPV) with well-defined end-groups is made available by performing the anionic polymerization in a continuous tubular reactor under flash chemistry conditions.
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36
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Sequence-defined nucleobase containing oligomers via reversible addition–fragmentation chain transfer single monomer addition. Polym Chem 2020. [DOI: 10.1039/c9py01853k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nucleobase acrylate monomers have been synthesized and monodisperse tetramers with any order of bases are created via single monomer insertion reactions in a RAFT process.
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37
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Automated Polymer Synthesis Platform for Integrated Conversion Targeting Based on Inline Benchtop NMR. ACS Macro Lett 2019; 8:1437-1441. [PMID: 35651185 DOI: 10.1021/acsmacrolett.9b00767] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
An automated polymer synthesis platform based on an inline low-field nuclear magnetic resonance spectrometer is developed. Flow chemistry and automated inline analyses are an excellent combination for automated kinetic screening and for self-optimizing reactions with programmable conversion targeting. By monitoring monomer conversion over a continuous range of reactor residence times, the platform is able to construct kinetic profiles of polymerizations in an accurate and efficient way. The machine-assisted self-optimization routine allows the reaction to be stopped at any given preselected conversion, giving rise to unprecedented reproducibility in polymer synthesis.
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38
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Deconstructing Oligomer Distributions: Discrete Species and Artificial Distributions. Angew Chem Int Ed Engl 2019; 58:13869-13873. [DOI: 10.1002/anie.201906842] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Indexed: 12/29/2022]
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39
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Kinetic Control of Aggregation Shape in Micellar Self‐Assembly. Angew Chem Int Ed Engl 2019; 58:13799-13802. [DOI: 10.1002/anie.201907371] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/04/2019] [Indexed: 01/08/2023]
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40
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Deconstructing Oligomer Distributions: Discrete Species and Artificial Distributions. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201906842] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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41
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Exploring the Photochemical Reactivity of Multifunctional Photocaged Dienes in Continuous Flow. CHEMPHOTOCHEM 2019. [DOI: 10.1002/cptc.201900142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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42
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Von Peptiden lernen: eine Strategie für das Design funktionaler Präzisionspolymer‐Sequenzen. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201902217] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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43
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Learning from Peptides to Access Functional Precision Polymer Sequences. Angew Chem Int Ed Engl 2019; 58:10747-10751. [DOI: 10.1002/anie.201902217] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Indexed: 12/29/2022]
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Influence of dielectric layer thickness and roughness on topographic effects in magnetic force microscopy. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:1056-1064. [PMID: 31165032 PMCID: PMC6541333 DOI: 10.3762/bjnano.10.106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
Magnetic force microscopy (MFM) has become a widely used tool for the characterization of magnetic properties. However, the magnetic signal can be overlapped by additional forces acting on the tip such as electrostatic forces. In this work the possibility to reduce capacitive coupling effects between tip and substrate is discussed in relation to the thickness of a dielectric layer introduced in the system. Single superparamagnetic iron oxide nanoparticles (SPIONs) are used as a model system, because their magnetic signal is contrariwise to the signal due to capacitive coupling so that it is possible to distinguish between magnetic and electric force contributions. Introducing a dielectric layer between substrate and nanoparticle the capacitive coupling can be tuned and minimized for thick layers. Using the theory of capacitive coupling and the magnetic point dipole-dipole model we could theoretically explain and experimentally prove the phase signal for single superparamagnetic nanoparticles as a function of the layer thickness of the dielectric layer. Tuning the capacitive coupling by variation of the dielectric layer thickness between nanoparticle and substrate allows the distinction between the electric and the magnetic contributions to the MFM signal. The theory also predicts decreasing topographic effects in MFM signals due to surface roughness of dielectric films with increasing film thickness.
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Laser-Grafted Molecularly Imprinted Polymers for the Detection of Histamine from Organocatalyzed Atom Transfer Radical Polymerization. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02339] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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47
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Precise Polymer Synthesis by Autonomous Self‐Optimizing Flow Reactors. Angew Chem Int Ed Engl 2019; 58:3183-3187. [DOI: 10.1002/anie.201810384] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/07/2018] [Indexed: 11/10/2022]
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Abstract
Discrete (monodisperse) methyl methacrylate (MMA) and di(ethylene glycol) ethyl ether acrylate (DEGEEA) oligomer libraries are generated via a 2-step process of RAFT polymerization and chromatographic separation.
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