scholarly journals 3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2720
Author(s):  
Anca-Dana Bendrea ◽  
Luminita Cianga ◽  
Gabriela-Liliana Ailiesei ◽  
Elena-Laura Ursu ◽  
Demet Göen Göen Colak ◽  
...  
Keyword(s):  
Self Assembly ◽  
Soft Materials ◽  
Future Research ◽  
Blue Color ◽  
High Concentration ◽  
Structural Details ◽  
End Group Functionalization ◽  
Lamellar Crystals ◽  
Experimental Findings ◽  
End Group

End-group functionalization of homopolymers is a valuable way to produce high-fidelity nanostructured and functional soft materials when the structures obtained have the capacity for self-assembly (SA) encoded in their structural details. Herein, an end-functionalized PCL with a π-conjugated EDOT moiety, (EDOT-PCL), designed exclusively from hydrophobic domains, as a functional “hydrophobic amphiphile”, was synthesized in the bulk ROP of ε-caprolactone. The experimental results obtained by spectroscopic methods, including NMR, UV-vis, and fluorescence, using DLS and by AFM, confirm that in solvents with extremely different polarities (chloroform and acetonitrile), EDOT-PCL presents an interaction- and structure-based bias, which is strong and selective enough to exert control over supramolecular packing, both in dispersions and in the film state. This leads to the diversity of SA structures, including spheroidal, straight, and helical rods, as well as orthorhombic single crystals, with solvent-dependent shapes and sizes, confirming that EDOT-PCL behaves as a “block-molecule”. According to the results from AFM imaging, an unexpected transformation of micelle-type nanostructures into single 2D lamellar crystals, through breakout crystallization, took place by simple acetonitrile evaporation during the formation of the film on the mica support at room temperature. Moreover, EDOT-PCL’s propensity for spontaneous oxidant-free oligomerization in acidic media was proposed as a presumptive answer for the unexpected appearance of blue color during its dissolution in CDCl3 at a high concentration. FT-IR, UV-vis, and fluorescence techniques were used to support this claim. Besides being intriguing and unforeseen, the experimental findings concerning EDOT-PCL have raised new and interesting questions that deserve to be addressed in future research.

pH-sensitivity and Conformation Change of the N-terminal Methacrylated Peptide VK20

MRS Advances ◽  
2017 ◽  
Vol 2 (47) ◽  
pp. 2571-2579 ◽  
Author(s):  
Zewang You ◽  
Marc Behl ◽  
Candy Löwenberg ◽  
Andreas Lendlein
Keyword(s):  
Conformational Changes ◽  
Self Assembly ◽  
Terminal Group ◽  
Random Coil ◽  
Coupling Reactions ◽  
End Group Functionalization ◽  
Physically Crosslinked ◽  
Influence Of Ph ◽  
Kinetics Of ◽  
End Group

ABSTRACTN-terminal methacrylation of peptide MAX1, which is capable of conformational changes by variation of the pH, results in a peptide, named VK20. Increasing the reactivity of this terminal group enables further coupling reactions or chemical modifications of the peptide. However, this end group functionalization may influence the ability of conformational changes of VK20, as well as its properties. In this paper, the influence of pH on the transition between random coil and ß-sheet conformation of VK20, including the transition kinetics, were investigated. At pH values of 9 and higher, the kinetics of ß-sheet formation increased for VK20, compared to MAX1. The self-assembly into ß-sheets recognized by the formation of a physically crosslinked gel was furthermore indicated by a significant increase of G’. An increase in pH (from 9 to 9.5) led to a faster gelation of the peptide VK20. Simultaneously, G’ was increased from 460 ± 70 Pa (at pH 9) to 1520 ± 180 Pa (at pH 9.5). At the nanoscale, the gel showed a highly interconnected fibrillary network structure with uniform fibril widths of approximately 3.4 ± 0.5 nm (N=30). The recovery of the peptide conformation back to random coil resulted in the dissolution of the gel, whereby the kinetics of the recovery depended on the pH. Conclusively, the ability of MAX1 to undergo conformational changes was not affected by N-terminal methacrylation whereas the kinetics of pH-sensitive ß-sheet formations has been increased.

scholarly journals Polyelectrolyte Gels: A Unique Class of Soft Materials

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 102
Author(s):  
Ferenc Horkay
Keyword(s):  
Exchange Process ◽  
Interaction Strength ◽  
Soft Materials ◽  
Industrial Applications ◽  
Future Research ◽  
Swelling Kinetics ◽  
Polyelectrolyte Gels ◽  
Ion Exchange Process ◽  
Counter Ions ◽  
Kinetics Of

The objective of this article is to introduce the readers to the field of polyelectrolyte gels. These materials are common in living systems and have great importance in many biomedical and industrial applications. In the first part of this paper, we briefly review some characteristic properties of polymer gels with an emphasis on the unique features of this type of soft material. Unsolved problems and possible future research directions are highlighted. In the second part, we focus on the typical behavior of polyelectrolyte gels. Many biological materials (e.g., tissues) are charged (mainly anionic) polyelectrolyte gels. Examples are shown to illustrate the effect of counter-ions on the osmotic swelling behavior and the kinetics of the swelling of model polyelectrolyte gels. These systems exhibit a volume transition as the concentration of higher valence counter-ions is gradually increased in the equilibrium bath. A hierarchy is established in the interaction strength between the cations and charged polymer molecules according to the chemical group to which the ions belong. The swelling kinetics of sodium polyacrylate hydrogels is investigated in NaCl solutions and in solutions containing both NaCl and CaCl2. In the presence of higher valence counter-ions, the swelling/shrinking behavior of these gels is governed by the diffusion of free ions in the swollen network, the ion exchange process and the coexistence of swollen and collapsed states.

End-Group-Functionalized Poly(α-olefinates) as Non-Polar Building Blocks: Self-Assembly of Sugar-Polyolefin Hybrid Conjugates

2016 ◽  
Vol 128 (15) ◽  
pp. 4761-4765 ◽  
Author(s):  
Tessy S. Thomas ◽  
Wonseok Hwang ◽  
Lawrence R. Sita
Keyword(s):  
Self Assembly ◽  
Building Blocks ◽  
End Group

scholarly journals Chirality, Gelation Ability and Crystal Structure: Together or Apart? Alkyl Phenyl Ethers of Glycerol as Simple LMWGs

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 732
Author(s):  
Alexander A. Bredikhin ◽  
Aidar T. Gubaidullin ◽  
Zemfira A. Bredikhina ◽  
Robert R. Fayzullin ◽  
Olga A. Lodochnikova
Keyword(s):  
Self Assembly ◽  
Chiral Recognition ◽  
Soft Materials ◽  
Gelling Agent ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Types ◽  
Low Molecular Weight Gelators ◽  
Phenyl Ethers

Chiral recognition plays an important role in the self-assembly of soft materials, in particular supramolecular organogels formed by low molecular weight gelators (LMWGs). Out of 14 pairs of the studied racemic and enantiopure samples of alkyl-substituted phenyl ethers of glycerol, only eight enantiopure diols form the stable gels in nonane. The formation of gels from solutions was studied by polarimetry, and their degradation with the formation of xerogels was studied by the PXRD method. The revealed crystalline characteristics of all studied xerogels corresponded to those for crystalline samples of the parent gelators. In addition to those previously investigated, crystalline samples of enantiopure para-n-alkylphenyl glycerol ethers [alkyl = pentyl (5), hexyl (6), heptyl (7), octyl (8), nonyl (9)] and racemic 3-(3,5-dimethylphenoxy)propane-1,2-diol (rac-14) have been examined by single crystal X-ray diffraction analysis. Among 22 samples of compounds 1-14 studied by SC-XRD, seven different types of supramolecular motifs are identified, of which only two are realized in crystals of supramolecular gelators. An attempt was made to relate the ability to gel formation with the characteristics of the supramolecular motif of a potential gelling agent, and the frequency of formation of the motif, required for gelation, with the chiral characteristics of the sample.

scholarly journals End group functionalization of poly(ethylene glycol) with phenolphthalein: towards star-shaped polymers based on supramolecular interactions

2014 ◽  
Vol 10 ◽  
pp. 2263-2269 ◽  
Author(s):  
Carolin Fleischmann ◽  
Hendrik Wöhlk ◽  
Helmut Ritter
Keyword(s):  
Ethylene Glycol ◽  
Cycloaddition Reaction ◽  
Supramolecular Interactions ◽  
Poly Ethylene Glycol ◽  
Naked Eye ◽  
Vis Spectroscopy ◽  
End Group Functionalization ◽  
Interesting Approach ◽  
Poly Ethylene ◽  
End Group

The synthesis of a new phenolphthalein azide derivative, which can be easily utilized in polymer analogous reactions, is presented. The subsequent cycloaddition reaction with propargyl-functionalized methoxypoly(ethylene glycol) yielded polymers bearing phenolphthalein as the covalently attached end group. In presence of per-β-cyclodextrin-dipentaerythritol, the formation of stable inclusion complexes was observed, representing an interesting approach towards the formation of star shaped polymers. The decolorization of a basic polymer solution caused by the complexation was of great advantage since this behavior enabled following the complex formation by UV–vis spectroscopy and even the naked eye.

scholarly journals Thermodynamics of structured fluids. Hard science for soft materials

2000 ◽  
Vol 72 (10) ◽  
pp. 1819-1834 ◽  
Author(s):  
John M. Prausnitz
Keyword(s):  
Self Assembly ◽  
Theoretical Calculations ◽  
Soft Materials ◽  
Confined Space ◽  
Molecular Physics ◽  
Fluid Structure ◽  
Light Emitting ◽  
Structured Fluids ◽  
Recent Developments ◽  
Narrow Space

At liquid-like densities, molecules of complex fluids can assume a variety of structures (or positions) in space; when the molecules contain many atoms as, for example, in polymers, that variety becomes very large. Further, when confined to a narrow space, it is possible to achieve structures that are not normally observed. Thanks to recent advances in statistical mechanics and molecular physics, and thanks to increasingly fast computers, it is now possible to calculate a fluid's structure, that is, the positions of molecules at equilibrium under given conditions. Calculation of fluid structure is useful because thermodynamic properties depend strongly on that structure, leading to possible applications for new materials. Three examples illustrate some recent developments; each example is presented only schematically (with a minimum of equations) to indicate the physical basis of the mathematical description. The first example considers the effect of branching on self-assembly (micellization) of copolymers (with possible long-range applications in medicine). The second and third examples consider the effect of confinement on fluid structure: first, crystallization in a narrow, confined space to produce a desired crystal structure (with possible applications for light-emitting diodes) and second, suppression of micellization of a diblock copolymer in a thin film (with possible application in lithography). Whenever possible, theoretical calculations are compared with experimental results.

scholarly journals Material Models to Study the Effect of Fines in Sandy Soils Based on Experimental and Numerical Results

2021 ◽  
Vol 14 (4) ◽  
pp. 651-680
Author(s):  
Ammar Alnmr
Keyword(s):  
Research Laboratory ◽  
Soft Soil ◽  
Sandy Soils ◽  
Soft Materials ◽  
Material Model ◽  
Future Research ◽  
Design Work ◽  
Material Models ◽  
Soil Material ◽  
Soil Model

Choosing and calibrating a robust and accurate soil material model (constitutive model) is the first important step in geotechnical numerical modelling. A less accurate model leads to poor results and more difficulty estimating true behaviour in the field. Subsequent design work is compromised and may lead to dangerous and costly mistakes. In this research, laboratory experimental results were used as a basis to evaluate several soil material models offered in Plaxis2D software. The deciding feature of the soil model was how well it could represent effects of percentage of fine material within sandy soils to simulate its behaviour. Results indicate that the Hardening Soil (HS) model works well when the percentage of fine (soft) materials is less than 10%. Above that level, the Soft Soil model (SS) becomes the most suitable.  Finally, some important conclusions about this research and recommendations for future research are highlighted.

Entrepreneurship in rural hospitality and tourism. A systematic literature review of past achievements and future promises

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Arun Thirumalesh Madanaguli ◽  
Puneet Kaur ◽  
Stefano Bresciani ◽  
Amandeep Dhir
Keyword(s):  
Literature Review ◽  
Systematic Literature Review ◽  
Empirical Studies ◽  
The Body ◽  
Future Research ◽  
Limited Attention ◽  
High Concentration ◽  
Content Type ◽  
Research Areas ◽  
Hospitality And Tourism

Purpose Entrepreneurship in the rural hospitality and tourism sector (RHT) has received wide attention in the past decade. However, a systematic review on this topic is currently lacking. This study aims to track the progress of the RHT and entrepreneurship literature by examining the various thematic research areas, identifying the research gaps and forecasting avenues of future research on the topic. Design/methodology/approach This paper catalogs and synthesizes the body of literature from the year 2000–2020 using a systematic literature review methodology. After discussing a brief history of RHT and entrepreneurship, the current study presents a review of 101 research articles. Findings The review highlights that RHT and entrepreneurship have received relatively limited attention from entrepreneurship journals. The content analysis revealed different gaps and limitations in the understanding of entrepreneurship in RHT, including a predominance of qualitative studies with limited theoretically-grounded and generalizable empirical studies. Furthermore, a high concentration of studies is from European countries. Six main thematic research areas were identified, namely, barriers and enablers, the roles of an entrepreneur, women in RHT, influencers of firm performance, innovation and value creation and methodological commonalities. The review also advances an RHT entrepreneurship ecosystem framework to summarize the findings. Originality/value Six promising research avenues are outlined based on the six themes identified. The suggested research questions draw from allied literature on small and medium businesses, innovation, women entrepreneurship and institutions to encourage the interdisciplinary cross-pollination of ideas. The findings are summarized in a novel research framework.

A Multi-User Computer-Aided Design Competition: Experimental Findings and Analysis of Team-Member Dynamics

2017 ◽  
Vol 17 (3) ◽  
Author(s):  
Brett Stone ◽  
John Salmon ◽  
Keenan Eves ◽  
Matthew Killian ◽  
Landon Wright ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Value Added ◽  
Future Research ◽  
Calendar Time ◽  
Competition Analysis ◽  
Computer Aided ◽  
Design Competition ◽  
Purdue Spatial Visualization Test ◽  
Experimental Findings ◽  
Aided Design

A competition for teams of three students using a prototype multi-user computer-aided design (MUCAD) tool was held to investigate various hypotheses regarding the performance of teams in such a setting. By comparing models from the competition to the same model in a single-user CAD environment, it is seen that use of a MUCAD system can significantly increase the value-added per unit of calendar time for a modeling effort. An investigation was also made into the causes of the performance differences among the various MUCAD teams which participated in the competition. Analysis of the results shows that teams that encouraged effective forms of communication and teams whose members scored similarly on the Purdue Spatial Visualization Test: Visualization of Rotations (PSVT:R) performed better than other teams. Areas of future research in analyzing teams in MUCAD environments are suggested.

scholarly journals Progress in Behavioral Game Theory

1997 ◽  
Vol 11 (4) ◽  
pp. 167-188 ◽  
Author(s):  
Colin F Camerer
Keyword(s):  
Game Theory ◽  
Social Values ◽  
Future Research ◽  
Backward Induction ◽  
Behavioral Game Theory ◽  
Dominated Strategies ◽  
Behavioral Game ◽  
Experimental Findings

Behavioral game theory aims to predict how people actually behave by incorporating psychological elements and learning into game theory. With this goal in mind, experimental findings can be organized into three categories: players have systematic 'reciprocated social values,' like desires for fairness and revenge. Phenomena discovered in studies of individual judgments and choices, like 'framing' and overconfidence, are also evident in games. Strategic principles, like irrelevance of strategy labels and timing of moves, iterated elimination of dominated strategies, and backward induction, are violated. Future research should incorporate these findings, along with learning and 'pregame theory,' into formal game theory.

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