Dendrons and Dendritic Terpolymers: Synthesis, Characterization and Self-Assembly Comparison

To the best of our knowledge, this is the very first time that a thorough study of the synthetic procedures, molecular and thermal characterization, followed by structure/properties relationship for symmetric and non-symmetric second generation (2-G) dendritic terpolymers is reported. Actually, the synthesis of the non-symmetric materials is reported for the first time in the literature. Anionic polymerization enables the synthesis of well-defined polymers that, despite the architecture complexity, absolute control over the average molecular weight, as well as block composition, is achieved. The dendritic type macromolecular architecture affects the microphase separation, because different morphologies are obtained, which do not exhibit long range order, and various defects or dislocations are evident attributed to the increased number of junction points of the final material despite the satisfactory thermal annealing at temperatures above the highest glass transition temperature of all blocks. For comparison reasons, the initial dendrons (miktoarm star terpolymer precursors) which are connected to each other in order to synthesize the final dendritic terpolymers are characterized in solution and in bulk and their self-assembly is also studied. A major conclusion is that specific structures are adopted which depend on the type of the core connection between the ligand and the active sites of the dendrons.

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Self-Assembly of Low-Molecular-Weight Asymmetric Linear Triblock Terpolymers: How Low Can We Go?

Molecules ◽

10.3390/molecules25235527 ◽

2020 ◽

Vol 25 (23) ◽

pp. 5527

Author(s):

Christina Miskaki ◽

Ioannis Moutsios ◽

Gkreti-Maria Manesi ◽

Konstantinos Artopoiadis ◽

Cheng-Yen Chang ◽

...

Keyword(s):

Self Assembly ◽

Low Molecular Weight ◽

Ordered Structures ◽

Low Dimensions ◽

X Ray ◽

Molecular Weights ◽

Transmission Electron ◽

First Time ◽

Triblock Terpolymers ◽

Structure Properties

The synthesis of two (2) novel triblock terpolymers of the ABC type and one (1) of the BAC type, where A, B and C are chemically different segments, such as polystyrene (PS), poly(butadiene) (PB1,4) and poly(dimethylsiloxane) (PDMS), is reported; moreover, their corresponding molecular and bulk characterizations were performed. Very low dimensions are evident from the characterization in bulk from transmission electron microscopy studies, verified by small-angle X-ray data, since sub-16 nm domains are evident in all three cases. The self-assembly results justify the assumptions that the high Flory–Huggins parameter, χ, even in low molecular weights, leads to significantly well-ordered structures, despite the complexity of the systems studied. Furthermore, it is the first time that a structure/properties relationship was studied for such systems in bulk, potentially leading to prominent applications in nanotechnology and nanopatterning, for as low as sub-10 nm thin-film manipulations.

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Single Amino Acid Based Self-Assemblies of Cysteine and Methionine

10.26434/chemrxiv.5972173.v1 ◽

2018 ◽

Author(s):

Nidhi Gour ◽

Bharti Koshti ◽

Chandra Kanth P. ◽

Dhruvi Shah ◽

Vivek Shinh Kshatriya ◽

...

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Self Assembly ◽

Aromatic Amino Acids ◽

Neutral Condition ◽

Single Amino Acid ◽

Binding Assays ◽

Human Neuroblastoma ◽

Cytotoxicity Assays ◽

First Time

We report for the very first time self-assembly of Cysteine and Methionine to discrenible strucutres under neutral condition. To get insights into the structure formation, thioflavin T and Congo red binding assays were done which revealed that aggregates may not have amyloid like characteristics. The nature of interactions which lead to such self-assemblies was purported by coincubating assemblies in urea and mercaptoethanol. Further interaction of aggregates with short amyloidogenic dipeptide diphenylalanine (FF) was assessed. While cysteine aggregates completely disrupted FF fibres, methionine albeit triggered fibrillation. The cytotoxicity assays of cysteine and methionine structures were performed on Human Neuroblastoma IMR-32 cells which suggested that aggregates are not cytotoxic in nature and thus, may not have amyloid like etiology. The results presented in the manuscript are striking, since to the best of our knowledge,this is the first report which demonstrates that even non-aromatic amino acids (cysteine and methionine) can undergo spontaneous self-assembly to form ordered aggregates.

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Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

10.26434/chemrxiv.7098695 ◽

2018 ◽

Author(s):

Elaine A. Kelly ◽

Judith E. Houston ◽

Rachel Evans

Keyword(s):

Real Time ◽

Absorption Spectroscopy ◽

Self Assembly ◽

Uv Light ◽

Wormlike Micelles ◽

Tetraethylene Glycol ◽

Light Illumination ◽

First Time ◽

Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such asdrug delivery and micellar catalysis. Currently, their behaviour in the equilibrium cis-and trans-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C8AzoOC8E4) using small-angle neutron scattering (SANS). We show that the incorporation of in-situUV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C8AzoOC8E4could switch between wormlike micelles (transnative state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked in-situthrough combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

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Insights on forming N,O-coordinated Cu single-atom catalysts for electrochemical reduction CO2 to methane

Nature Communications ◽

10.1038/s41467-020-20769-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yanming Cai ◽

Jiaju Fu ◽

Yang Zhou ◽

Yu-Chung Chang ◽

Qianhao Min ◽

...

Keyword(s):

Energy Barrier ◽

Active Sites ◽

Theoretical Calculations ◽

High Energy ◽

Single Atom ◽

Faradaic Efficiency ◽

High Energy Barrier ◽

Catalytic Sites ◽

Electron Reduction ◽

First Time

AbstractSingle-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN2O2 sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO2 to CH4 with current density of 40 mA·cm-2 in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

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Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Molecules ◽

10.3390/molecules26154705 ◽

2021 ◽

Vol 26 (15) ◽

pp. 4705

Author(s):

Boer Liu ◽

Xi Chen ◽

Glenn A. Spiering ◽

Robert B. Moore ◽

Timothy E. Long

Keyword(s):

Hydrogen Bonding ◽

Self Assembly ◽

Microphase Separation ◽

Triblock Copolymers ◽

Random Copolymer ◽

Thermomechanical Properties ◽

Structure Property ◽

Scanning Calorimetry ◽

Central Block ◽

Quadruple Hydrogen Bonding

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

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Interactions between an Associative Amphiphilic Block Polyelectrolyte and Surfactants in Water: Effect of Charge Type on Solution Properties and Aggregation

Polymers ◽

10.3390/polym13111729 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1729

Author(s):

Patrizio Raffa

Keyword(s):

Surface Tension ◽

Self Assembly ◽

Interaction Model ◽

Industrial Applications ◽

Molecular Organization ◽

Different Types ◽

Solution Rheology ◽

Interesting Class ◽

First Time

The study of interactions between polyelectrolytes (PE) and surfactants is of great interest for both fundamental and applied research. These mixtures can represent, for example, models of self-assembly and molecular organization in biological systems, but they are also relevant in industrial applications. Amphiphilic block polyelectrolytes represent an interesting class of PE, but their interactions with surfactants have not been extensively explored so far, most studies being restricted to non-associating PE. In this work, interactions between an anionic amphiphilic triblock polyelectrolyte and different types of surfactants bearing respectively negative, positive and no charge, are investigated via surface tension and solution rheology measurements for the first time. It is evidenced that the surfactants have different effects on viscosity and surface tension, depending on their charge type. Micellization of the surfactant is affected by the presence of the polymer in all cases; shear viscosity of polymer solutions decreases in presence of the same charge or nonionic surfactants, while the opposite charge surfactant causes precipitation. This study highlights the importance of the charge type, and the role of the associating hydrophobic block in the PE structure, on the solution behavior of the mixtures. Moreover, a possible interaction model is proposed, based on the obtained data.

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Taming nitroformate through encapsulation with nitrogen-rich hydrogen-bonded organic frameworks

Nature Communications ◽

10.1038/s41467-021-22475-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jichuan Zhang ◽

Yongan Feng ◽

Richard J. Staples ◽

Jiaheng Zhang ◽

Jean’ne M. Shreeve

Keyword(s):

Thermal Stability ◽

Hydrogen Bonds ◽

Self Assembly ◽

Energetic Materials ◽

Decomposition Temperature ◽

High Oxygen Content ◽

The Poor ◽

Simple Preparation ◽

First Time ◽

Hydrogen Bonded

AbstractOwing to its simple preparation and high oxygen content, nitroformate [−C(NO2)3, NF] is an extremely attractive oxidant component for propellants and explosives. However, the poor thermostability of NF-based derivatives has been an unconquerable barrier for more than 150 years, thus hindering its application. In this study, the first example of a nitrogen-rich hydrogen-bonded organic framework (HOF-NF) is designed and constructed through self-assembly in energetic materials, in which NF anions are trapped in pores of the resulting framework via the dual force of ionic and hydrogen bonds from the strengthened framework. These factors lead to the decomposition temperature of the resulting HOF-NF moiety being 200 °C, which exceeds the challenge of thermal stability over 180 °C for the first time among NF-based compounds. A large number of NF-based compounds with high stabilities and excellent properties can be designed and synthesized on the basis of this work.

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Sol–gel synthesis of 2-dimensional TiO2: self-assembly of Ti–oxoalkoxy–acetate complexes by carboxylate ligand directed condensation

Faraday Discussions ◽

10.1039/c9fd00108e ◽

2021 ◽

Cited By ~ 1

Author(s):

Ruohong Sui ◽

Connor E. Deering ◽

Rohen Prinsloo ◽

Christopher B. Lavery ◽

Nancy Chou ◽

...

Keyword(s):

Self Assembly ◽

Sol Gel ◽

Carboxylate Ligand ◽

Sol Gel Synthesis ◽

First Time

2-Dimensional TiO2 is synthesized for the first time by a sol–gel self-assembly of Ti–oxoalkoxy–acetate complexes.

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Synthesis and self-assembly behaviour of poly(Nα-Boc-l-tryptophan)-block-poly(ethylene glycol)-block-poly(Nα-Boc-l-tryptophan)

RSC Advances ◽

10.1039/c6ra03718f ◽

2016 ◽

Vol 6 (29) ◽

pp. 24142-24153

Author(s):

Andreea S. Voda ◽

Kevin Magniez ◽

Nisa V. Salim ◽

Cynthia Wong ◽

Qipeng Guo

Keyword(s):

Drug Delivery ◽

Ethylene Glycol ◽

Self Assembly ◽

Triblock Copolymers ◽

Potential Drug ◽

Poly Ethylene Glycol ◽

Drug Delivery Applications ◽

Poly Ethylene ◽

First Time

We report for the first time the use of Nα-Boc-l-tryptophan for the synthesis of amphiphilic BAB triblock copolymers for potential drug delivery applications.

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Self-assembly synthesis of nitrogen-doped mesoporous carbons used as high-performance electrode materials in lithium-ion batteries and supercapacitors

New Journal of Chemistry ◽

10.1039/c7nj02532g ◽

2017 ◽

Vol 41 (21) ◽

pp. 12901-12909 ◽

Cited By ~ 11

Author(s):

Chunfeng Shao ◽

Ziqiang Wang ◽

Errui Wang ◽

Shujun Qiu ◽

Hailiang Chu ◽

...

Keyword(s):

Electrochemical Performance ◽

Lithium Ion Batteries ◽

Self Assembly ◽

High Performance ◽

Electrode Materials ◽

Lithium Ion ◽

Mesoporous Carbons ◽

Nitrogen Doped ◽

First Time ◽

Enhanced Electrochemical Performance

Guanine was, for the first time, used as a nitrogen source during the synthesis of nitrogen-doped porous carbons (NMCs) with enhanced electrochemical performance.

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