scholarly journals Making and Breaking of Gels: Stimuli-Responsive Properties of Bis(Pyridyl-N-oxide Urea) Gelators

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6420
Author(s):  
Sreejith Sudhakaran Jayabhavan ◽  
Dipankar Ghosh ◽  
Krishna K. Damodaran
Keyword(s):  
Structural Modification ◽  
Sol Gel ◽  
Stimuli Responsive ◽  
Responsive Materials ◽  
Sol Gel Transition ◽  
Rheological Experiments ◽  
The Stability ◽  
External Stimuli ◽  
Chloride Salts ◽  
Gel Network

The structural modification of existing supramolecular architecture is an efficient strategy to design and synthesize supramolecular gels with tunable and predictable properties. In this work, we have modified bis(pyridyl urea) compounds with different linkers, namely hexylene and butylene, to their corresponding bis(pyridyl-N-oxide urea). The gelation properties of both the parent and the modified compounds were studied, and the results indicated that modification of the 3-pyridyl moieties to the corresponding 3-pyridyl-N-oxides induced hydrogelation. The stability of the parent and modified compounds were evaluated by sol-gel transition temperature (Tgel) and rheological measurements, and single-crystal X-ray diffraction was used to analyze the solid-state interactions of the gelators. The morphologies of the dried gels were analyzed by scanning electron microscopy (SEM), which revealed that the structural modification did not induce any prominent effect on the gel morphology. The stimuli-responsive behavior of these gels in the presence of salts in DMSO/water was evaluated by rheological experiments, which indicated that the modified compounds displayed enhanced gel strength in most cases. However, the gel network collapsed in the presence of the chloride salts of aluminum(III), zinc(II), copper(II), and cadmium(II). The mechanical strength of the parent gels decreased in the presence of salts, indicating that the structural modification resulted in robust gels in most cases. The modified compounds formed gels below minimum gel concentration in the presence of various salts, indicating salt-induced gelation. These results show the making and breaking ability of the gel network in the presence of external stimuli (salts), which explains the potential of using LMWGs based on N-oxide moieties as stimuli-responsive materials.

Smart Polymers and their Applications: A Review

2017 ◽  
Vol 8 (03) ◽  
Author(s):  
Gore S. A. ◽  
Gholve S. B. ◽  
Savalsure S. M. ◽  
Ghodake K. B. ◽  
Bhusnure O. G. ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Water Soluble ◽  
Solution Temperature ◽  
Smart Polymers ◽  
Stimuli Responsive ◽  
Responsive Materials ◽  
Water Soluble Polymers ◽  
Commercial Applications ◽  
Stimuli Sensitive ◽  
External Stimuli

Smart polymers are materials that respond to small external stimuli. These are also referred as stimuli responsive materials or intelligent materials. Smart polymers that can exhibit stimuli-sensitive properties are becoming important in many commercial applications. These polymers can change shape, strength and pore size based on external factors such as temperature, pH and stress. The stimuli include salt, UV irradiation, temperature, pH, magnetic or electric field, ionic factors etc. Smart polymers are very promising applicants in drug delivery, tissue engineering, cell culture, gene carriers, textile engineering, oil recovery, radioactive wastage and protein purification. The study is focused on the entire features of smart polymers and their most recent and relevant applications. Water soluble polymers with tunable lower critical solution temperature (LCST) are of increasing interest for biological applications such as cell patterning, smart drug release, DNA sequencing etc.

scholarly journals Molecularly engineered switchable photo-responsive membrane in gas separation for environmental protection

2019 ◽  
Vol 25 (4) ◽  
pp. 447-461 ◽  
Author(s):  
Aishah Rosli ◽  
Siew Chun Low
Keyword(s):  
Environmental Protection ◽  
Gas Separation ◽  
Energy Costs ◽  
Stimuli Responsive ◽  
Responsive Materials ◽  
Separation Systems ◽  
Non Invasive ◽  
Responsive Membranes ◽  
External Stimuli

In recent years, stimuli-responsive materials have garnered interest due to their ability to change properties when exposed to external stimuli, making it useful for various applications including gas separation. Light is a very attractive trigger for responsive materials due to its speedy and non-invasive nature as well as the potential to reduce energy costs significantly. Even though light is deemed as an appealing stimulus for the development of stimuli-responsive materials, this avenue has yet to be extensively researched, as evidenced by the fewer works done on the photo-responsive membranes. Of these, there are even less research done on photo-responsive materials for the purpose of gas separation, thus, we have collected the examples that answer both these criteria in this review. This review covers the utilisation of photo-responsive materials specifically for gas separation purposes. Photo-chromic units, their integration into gas separation systems, mechanism and research that have been done on the topic so far are discussed.

scholarly journals The Smoluchowski Ensemble—Statistical Mechanics of Aggregation

Entropy ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1181
Author(s):  
Themis Matsoukas
Keyword(s):  
Sol Gel ◽  
Scaling Limit ◽  
Mean Field ◽  
Central Element ◽  
Field Approximation ◽  
Fixed Number ◽  
Mean Field Approximation ◽  
The Mean ◽  
Sol Gel Transition ◽  
The Stability

We present a rigorous thermodynamic treatment of irreversible binary aggregation. We construct the Smoluchowski ensemble as the set of discrete finite distributions that are reached in fixed number of merging events and define a probability measure on this ensemble, such that the mean distribution in the mean-field approximation is governed by the Smoluchowski equation. In the scaling limit this ensemble gives rise to a set of relationships identical to those of familiar statistical thermodynamics. The central element of the thermodynamic treatment is the selection functional, a functional of feasible distributions that connects the probability of distribution to the details of the aggregation model. We obtain scaling expressions for general kernels and closed-form results for the special case of the constant, sum and product kernel. We study the stability of the most probable distribution, provide criteria for the sol-gel transition and obtain the distribution in the post-gel region by simple thermodynamic arguments.

A “keto–enol tautomerization”-based response mechanism: a novel approach to stimuli-responsive supramolecular gel

2015 ◽  
Vol 51 (61) ◽  
pp. 12224-12227 ◽  
Author(s):  
Qi Lin ◽  
Tao-Tao Lu ◽  
Jin-Chao Lou ◽  
Gui-Yuan Wu ◽  
Tai-Bao Wei ◽  
...  
Keyword(s):  
Sol Gel ◽  
Stimuli Responsive ◽  
Response Mechanism ◽  
Aggregation Induced Emission ◽  
Supramolecular Gel ◽  
Dual Channel ◽  
Novel Approach ◽  
Specific Selectivity ◽  
Sol Gel Transition ◽  
Gel Transition

By “keto–enol tautomerization”, gelator G3 can be self-assembled into a stable organogel (OG3) accompanied by strong aggregation induced emission (AIE). OG3 could dual-channel sense S2− with specific selectivity via reversible sol–gel transition and fluorescent changes.

AN INSIGHT INTO FIBER–SOLVENT MEDIATED MODULATION OF NANO-FIBRILLAR ORGANOGELS

2011 ◽  
Vol 10 (04n05) ◽  
pp. 547-554
Author(s):  
SUMAN K. SAMANTA ◽  
ASISH PAL ◽  
SANTANU BHATTACHARYA
Keyword(s):  
Chain Length ◽  
Sol Gel ◽  
Differential Scanning Calorimetric ◽  
Scanning Calorimetry ◽  
Electron Microscopic ◽  
X Ray ◽  
Sol Gel Transition ◽  
Rheological Experiments ◽  
Calorimetric Studies ◽  
Scanning Electron

The effect of gelation and the modulation of their properties with the variation of aliphatic hydrocarbon solvents, e.g., n-decane and n-dodecane have been presented for a homologous series of amides of L-alanine with fatty acids. The gelation properties of these compounds were studied by a number of physical methods including scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, rheology etc. It was found that the gelation properties vary with the chain length of the host aliphatic hydrocarbons. Scanning electron microscopic images showed modulation of the fiber diameters upon changing the solvent from n-decane to n-dodecane and this has been confirmed by the results obtained from small angle X-ray scattering studies independently. Thermal properties were observed under the differential scanning calorimetric studies which showed an increase in the sol–gel transition temperatures upon increase in the chain length of the hydrocarbon solvent. The mechanical behavior of such assemblies has been observed under rheological experiments which showed a more viscoelastic response for the gels in n-decane compared to n-dodecane.

scholarly journals 4D Printing: dawn of an emerging technology cycle

2014 ◽  
Vol 34 (4) ◽  
pp. 310-314 ◽  
Author(s):  
Eujin Pei
Keyword(s):  
State Of The Art ◽  
Emerging Technology ◽  
Stimuli Responsive ◽  
4D Printing ◽  
Content Type ◽  
Responsive Materials ◽  
Covering Material ◽  
Definition Of ◽  
New Applications ◽  
External Stimuli

Purpose – The purpose of this article is to reviews state-of-the-art developments in four-dimensional (4D) printing, discuss what it is, investigate new applications that have been discovered and suggest its future impact. Design/methodology/approach – The article clarifies the definition of 4D printing and describes notable examples covering material science, equipment and applications. Findings – This article highlights an emerging technology cycle where 4D printing research has gained traction within additive manufacturing. The use of stimuli-responsive materials can be programmed and printed to enable pre-determined reactions when subject to external stimuli. Originality/value – This article reviews state-of-the-art developments in 4D printing, discusses what it is, investigates new applications that have been discovered and suggests its future impact.

Effect of dimethylsulfoxide on the viscoelastic properties and sol–gel transition of cellulose/ionic liquid solutions

RSC Advances ◽  
2015 ◽  
Vol 5 (11) ◽  
pp. 8318-8322 ◽  
Author(s):  
H. Saba ◽  
Y. Yongbo ◽  
W. Jianning ◽  
X. Xiaolin ◽  
W. Kaijian ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Viscoelastic Properties ◽  
Sol Gel ◽  
Liquid Solutions ◽  
Sol Gel Transition ◽  
Rheological Experiments ◽  
Gel Transition

Viscoelastic properties of cellulose solutions with 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and dimethylsulfoxide (DMSO) as solvents were studied by rheological experiments.

Photo Gel-Sol/Sol-Gel Transition and Its Patterning of a Supramolecular Hydrogel as Stimuli-Responsive Biomaterials

2008 ◽  
Vol 14 (13) ◽  
pp. 3977-3986 ◽  
Author(s):  
Shinji Matsumoto ◽  
Satoshi Yamaguchi ◽  
Shiori Ueno ◽  
Harunobu Komatsu ◽  
Masato Ikeda ◽  
...  
Keyword(s):  
Sol Gel ◽  
Stimuli Responsive ◽  
Supramolecular Hydrogel ◽  
Sol Gel Transition ◽  
Gel Transition

Phase Separation of Carboxylated Poly-L-lysine

2014 ◽  
Vol 1622 ◽  
pp. 129-133
Author(s):  
Esha Das ◽  
Kazuaki Matsumura
Keyword(s):  
Phase Separation ◽  
Electric Fields ◽  
Sudden Change ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Responsive Materials ◽  
Solvation State ◽  
External Stimuli

ABSTRACTStimuli-responsive materials are capable of reversibly altering their properties depending on the environmental conditions or external stimuli. External stimuli typically include thermal, pH, electric fields, optical, magnetic fields, mechanical forces and chemical interactions. There are many instances in nature where responsive surfaces have been observed. Temperature is the most widely used stimulus in environmentally responsive polymer systems. The change of temperature is not only relatively easy to control, but also easily applicable both in vitro and in vivo. Temperature responsive polymers exhibit a phase transition at a certain temperature, which causes a sudden change in the solvation state. Polymers that become insoluble upon heating have a so-called lower critical solution temperature (LCST). One example of these polymers is poly (N-isopropyl acrylamide), which shows LCST at about 32 °C, close to the physiological temperature. In this study, we report the developing of novel polyampholytes which shows thermo-, salt-responsive liquid-liquid phase separation in aqueous solution.

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