scholarly journals Special Issue: Nanocomposite Hydrogels for Biomedical Applications

2020 ◽  
Vol 10 (1) ◽  
pp. 389 ◽  
Author(s):  
Kazuaki Matsumura
Keyword(s):  
Biomedical Applications ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Special Issue ◽  
Nanocomposite Hydrogels ◽  
Dimensional Network

A hydrogel consists of a three-dimensional network of polymer chains, with water as a solvent in the system [...]

Chemical Stress Relaxation of NR Networks Prepared in the Swollen State

1986 ◽  
Vol 59 (4) ◽  
pp. 541-550 ◽  
Author(s):  
Kyung-Do Suh ◽  
Hidetoshi Oikawa ◽  
Kenkichi Murakami
Keyword(s):  
Stress Relaxation ◽  
Network Structure ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Chemical Stress ◽  
Network Chain ◽  
Crosslinking Process ◽  
Dimensional Network ◽  
Chemical Relaxation ◽  
The Difference

Abstract From the experimental results of the present investigation, it is apparent that two kinds of networks which have a different three-dimensional network structure give quite different behavior of chemical stress relaxation, even if both networks have the same network chain density. The difference in three-dimensional network structure for the two kinds of rubber arises from the degree of entanglement, which changes with the concentration of the polymer chains prior to the crosslinking process. The direct cause of chemical relaxation is due to the scission of network chains by degradation, whereas the total relaxation is caused by the change of geometrical conformation of network chains. This then casts doubt on the basic concept of chemorheology which is represented by Equation 2.

One-dimensional CuIIcoordination polymers containingC2h-symmetric 1,1′:4′,1′′-terphenyl-3,3′-dicarboxylate linkers

2015 ◽  
Vol 71 (10) ◽  
pp. 929-935 ◽  
Author(s):  
Hyun-Chul Kim ◽  
Ja-Min Gu ◽  
Seong Huh ◽  
Chul-Hyun Yo ◽  
Youngmee Kim
Keyword(s):  
Coordination Polymers ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Water Molecules ◽  
Binding Modes ◽  
Bridging Ligands ◽  
One Dimensional ◽  
X Ray Crystallography ◽  
Dimensional Network ◽  
The One

Two new one-dimensional CuIIcoordination polymers (CPs) containing theC2h-symmetric terphenyl-based dicarboxylate linker 1,1′:4′,1′′-terphenyl-3,3′-dicarboxylate (3,3′-TPDC), namelycatena-poly[[bis(dimethylamine-κN)copper(II)]-μ-1,1′:4′,1′′-terphenyl-3,3′-dicarboxylato-κ4O,O′:O′′:O′′′] monohydrate], {[Cu(C20H12O4)(C2H7N)2]·H2O}n, (I), andcatena-poly[[aquabis(dimethylamine-κN)copper(II)]-μ-1,1′:4′,1′′-terphenyl-3,3′-dicarboxylato-κ2O3:O3′] monohydrate], {[Cu(C20H12O4)(C2H7N)2(H2O)]·H2O}n, (II), were both obtained from two different methods of preparation: one reaction was performed in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) as a potential pillar ligand and the other was carried out in the absence of the DABCO pillar. Both reactions afforded crystals of different colours,i.e.violet plates for (I) and blue needles for (II), both of which were analysed by X-ray crystallography. The 3,3′-TPDC bridging ligands coordinate the CuIIions in asymmetric chelating modes in (I) and in monodenate binding modes in (II), forming one-dimensional chains in each case. Both coordination polymers contain two coordinated dimethylamine ligands in mutuallytranspositions, and there is an additional aqua ligand in (II). The solvent water molecules are involved in hydrogen bonds between the one-dimensional coordination polymer chains, forming a two-dimensional network in (I) and a three-dimensional network in (II).

Liquid Crystal Elastomers with Piezoelectric Properties

MRS Bulletin ◽  
1991 ◽  
Vol 16 (1) ◽  
pp. 29-31 ◽  
Author(s):  
Wolfgang Meier ◽  
Heino Finkelmann
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Side Chain ◽  
Shape Stability ◽  
Technical Application ◽  
Mechanical Field ◽  
Dimensional Network ◽  
Liquid Crystal Elastomers

During the last few years, liquid crystalline elastomers (LCEs) have been systematically produced by cross-linking liquid crystalline side-chain polymers. In these networks, a liquid crystalline molecule is fixed at each monomeric unit. LCEs exhibit a novel combination of properties. Due to liquid crystalline groups, they show anisotropic liquid crystalline properties similar to conventional liquid crystals (LCs); but due to the three-dimensional network-structure of the polymer chains, they show typical elastomer properties, such as rubber elasticity or shape stability. One exceptional property of this combination is demonstrated when a mechanical deformation to the LCE causes macroscopically uniform orientation of the long molecular axis of the LC units (the so-called “director”).This response of the LC-phase structure to an applied mechanical field is similar to the effect of electric or magnetic fields on low molecular weight liquid crystals (LMLC), as illustrated in Figure 1. Figure la shows an undeformed LCE. Because of the non-uniform orientation of the director, the sample scatters light strongly so the elastomer is translucent like frosted glass. On the other hand, applying a mechanical field the director becomes uniformly aligned and the sample is transparent (Figure 1b). Such a macroscopically ordered rubber exhibits optical properties very similar to single crystals. These propertie s of LCEs offer new prospects for technical application, e.g., in nonlinear and integrated optics.

Development of a Collagen/Clay Nanocomposite Biomaterial

2012 ◽  
Vol 706-709 ◽  
pp. 461-466 ◽  
Author(s):  
Alejandra Reyna-Valencia ◽  
P. Chevallier ◽  
D. Mantovani
Keyword(s):  
Mechanical Properties ◽  
Aqueous Media ◽  
Three Dimensional ◽  
Clay Particles ◽  
Network Characteristics ◽  
Polymer Molecules ◽  
Nanocomposite Hydrogels ◽  
Clay Concentration ◽  
Dimensional Network ◽  
Collagen Hydrogels

Collagen hydrogels are widely used as three-dimensional scaffolds for cells and tissue in culture environments. These materials, which consist of crosslinked biopolymer (protein-based) networks in aqueous media, are particularly suitable for recreating part of the extra-cellular matrix, but their poor mechanical properties represent a major limitation. One strategy to enhance the strength of this kind of hydrogels might be to incorporate clay nanoscopic particles. In fact, it has been observed that the charged surface of clay nanosheets can interact with certain functional groups belonging to polymer molecules, yielding stronger networks. Moreover, clay particles are recognized to be biocompatible. In the present work, the gelation process and the resulting morphological and mechanical properties of collagen/laponite clay nanocomposite hydrogels were invastigated. Upon gelation, the biopolymer molecules assemble into nanoscale fibrils, which bundle into fibers and entangle into a three-dimensional network. The network characteristics depend on tunable parameters such as pH and clay concentration.

scholarly journals Hydrogels for management of chronic wound healing

2021 ◽  
Vol 5 (3) ◽  
pp. 095-104
Author(s):  
IM Cardoso-Daodu ◽  
CP Azubuike ◽  
MO Ilomuanya
Keyword(s):  
Wound Healing ◽  
Chronic Wounds ◽  
Healing Process ◽  
Three Dimensional ◽  
Scar Tissue ◽  
The Body ◽  
Polymer Chains ◽  
Wound Healing Process ◽  
Dimensional Network ◽  
Healing Wound

Chronic wounds occur when one wound healing process or a sequence of wound healing events are affected resulting in slow healing of the wound thereby placing the patient in deep pain. Various diseases and conditions can delay the process of wound healing. Wound healing can be classified into four main stages: hemostasis, inflammation, remodeling, and scar tissue formation with each phase overlapping one another. The skin is the largest organ in the body. It protects the entire external surface of the human body and is the primary site of interaction with the outside environment. There is therefore a need to fabricate an ideal dressing through scientific research and investigations. Hydrogels are a three-dimensional network of hydrophilic polymers that can swell in water and absorb copious amounts of water while maintaining their structure because of their chemical or physical crosslinking of individual polymer chains. A hydrogel must be composed of at least 10% water. Hydrogels possess the flexibility and water percentage which is remarkably like tissues. They are biocompatible and biodegradable which makes them ideal for dermal wound healing.

scholarly journals Crystal structure of catena-poly[[[bis(3-oxo-1,3-diphenylprop-1-enolato-κ2 O,O′)zinc(II)]-μ2-tris[4-(pyridin-3-yl)phenyl]amine-κ2 N:N′] tetrahydrofuran monosolvate]

2019 ◽  
Vol 75 (10) ◽  
pp. 1432-1435
Author(s):  
Yukiyasu Kashiwagi ◽  
Koji Kubono ◽  
Toshiyuki Tamai
Keyword(s):  
Coordination Polymer ◽  
Crystal Packing ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Coordination Geometry ◽  
Asymmetric Unit ◽  
One Dimensional ◽  
Π Interactions ◽  
Dimensional Network ◽  
Sheet Structure

The reaction of bis(3-oxo-1,3-diphenylprop-1-enolato-κ2 O,O′)zinc(II), [Zn(dbm)2], with tris[4-(pyridin-3-yl)phenyl]amine (T3PyA) in tetrahydrofuran (THF) afforded the title crystalline coordination polymer, {[Zn(C15H11O2)2(C33H24N4)]·C4H8O} n . The asymmetric unit contains two independent halves of Zn(dbm)2, one T3PyA and one THF. Each ZnII atom is located on an inversion centre and adopts an elongated octahedral coordination geometry, ligated by four O atoms of two dbm ligands in equatorial positions and by two N atoms of pyridine moieties from two different bridging T3PyA ligands in axial positions. The crystal packing shows a one-dimensional polymer chain in which the two pyridyl groups of the T3PyA ligand bridge two independent Zn atoms of Zn(dbm)2. In the crystal, the coordination polymer chains are linked via C—H...π interactions into a sheet structure parallel to (010). The sheets are cross-linked via further C—H...π interactions into a three-dimensional network. The solvate THF molecule shows disorder over two sets of atomic sites having occupancies of 0.631 (7) and 0.369 (7).

scholarly journals Mechanical and Swelling Characteristics of Kappa-carrageenin/Poly-N-isopropylacrylamide Blend Hydrogels

2017 ◽  
Vol 4 (1) ◽  
pp. 61
Author(s):  
Zhang Yalong ◽  
Zhang Yanqun ◽  
Yi Min ◽  
Ha Hongfei
Keyword(s):  
Three Dimensional ◽  
Polymer Chains ◽  
Linear Polymer ◽  
Temperature Sensitive ◽  
Swelling Properties ◽  
Radiation Technology ◽  
Dimensional Network ◽  
Swelling Characteristics ◽  
Unreacted Monomer ◽  
Main Component

Two- or multi-component hydrogels consisting of the three-dimensional network of polymer chains play more and more significant role in the field of biomaterials such as contact lens, burn dressing drug delivery systems etc or in some technical fields such as gel actuators, sensors, absorbents etc. In the work, a novel blend hydrogel composed of kappa-carrageenin (KC) and polyisopropylacrylamide (PNIPAAm) was prepared via gamma-radiation technology at room temperature. The main component of the hydrogels is a typical temperature sensitive polymer PNIPAAm. As the second component, KC is a kind of natural macromolecules. The properties of the gels, such as gel strength, and swelling behavior were investigated. The incorporation of relatively small content (up to 5 wt.%) of KC could obviously improve the mechanical properties and swelling capacity. 3% KC content in the blend hydrogel is preferable for better strength and swelling properties. On the other hand, as a kind of polysaccharide, KC would be degraded by γ-rays; so<br />suitable dose must be controlled carefully. Here the total dose used was controlled below 3 kGy. KC is soluble in water. If the hydrogels synthesized in the work were as usually extracted in water or other polar solvent such as methanol, the KC in hydrogels would be also washed out completely together with unreacted monomer and linear polymer, and the action of KC in the blend hydrogels would be disappeared. Otherwise, the results published before showed that the unreacted monomer and linear polymer in the hydrogels were very small, no more than 3-5%, which would not affect the properties of the hydrogels.

Synthesis and Applications of Hydrogels in Cancer Therapy

2020 ◽  
Vol 20 (12) ◽  
pp. 1431-1446
Author(s):  
Anchal Singhal ◽  
Niharika Sinha ◽  
Pratibha Kumari ◽  
Manoushikha Purkayastha
Keyword(s):  
Drug Delivery ◽  
Tissue Engineering ◽  
Cancer Therapy ◽  
Mechanical Strength ◽  
Biomedical Applications ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Human Tissues ◽  
Methods Of Synthesis

: Hydrogels are water-insoluble, hydrophilic, cross-linked, three-dimensional networks of polymer chains having the ability to swell and absorb water but do not dissolve in it, that comprise the major difference between gels and hydrogels. The mechanical strength, physical integrity and solubility are offered by the crosslinks. The different applications of hydrogels can be derived based on the methods of their synthesis, response to different stimuli, and their different kinds. Hydrogels are highly biocompatible and have properties similar to human tissues that make it suitable to be used in various biomedical applications, including drug delivery and tissue engineering. The role of hydrogels in cancer therapy is highly emerging in recent years. In the present review, we highlighted different methods of synthesis of hydrogels and their classification based on different parameters. Distinctive applications of hydrogels in the treatment of cancer are also discussed.

scholarly journals Interpenetrating polymeric hydrogels as favorable materials for hygienic applications

2020 ◽  
Vol 10 (2) ◽  
pp. 5011-5020
Keyword(s):  
Biomedical Applications ◽  
Three Dimensional ◽  
Synthetic Polymers ◽  
Poly Vinyl Alcohol ◽  
Ambient Conditions ◽  
Natural Polymers ◽  
Dimensional Network ◽  
Swelling Capacity ◽  
Polymeric Chains ◽  
Poly Ethylene

Polymers can crosslink to produce intermingled materials with three-dimensional network structure known as interpenetrating polymeric network (IPN). They comprise elastic crosslinked polymeric chains. The chains of the hydrogels are either physically or chemically entangled together. Interpenetrating hydrogels can be tailored to provide enhanced materials. They can be classified according to methods of their synthesis as simultaneous or sequential IPNs and the structure to be homo or semi IPNs. The preparation factors play a role in controlling the properties of the produced IPNs. Moreover, the ambient conditions such as pH, temperature as well as the ionic strength may affect the performance of these hydrogels. The swelling capacity is an important feature that allows the prepared hydrogel to perform the required application. Some disadvantages may arise such as the low mechanical properties that are suggested to be overcome. IPNs can be used in various applications that serve the human requirements like drug delivery, tissue engineering, medical and packaging applications. Hydrogels present biocompatibility and nontoxicity when used in biomedical applications. Interpenetrating hydrogels can be prepared from natural or synthetic polymers. Polysaccharides as natural polymers can be used to produce efficient interpenetrating hydrogels. Polyacrylates, poly(ethylene glycol) and poly(vinyl alcohol) are designated as promising synthetic polymers capable of forming interpenetrating hydrogels.

scholarly journals Special Issue “Sustainable Remediation Processes Based on Zeolites”

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2153
Author(s):  
Claudia Belviso
Keyword(s):  
General Formula ◽  
Divalent Cations ◽  
Three Dimensional ◽  
Special Issue ◽  
Sustainable Remediation ◽  
Dimensional Network

Zeolites are microporous tectosilicates characterized by a three-dimensional network of tetrahedral (Si, Al)O4 units with the general formula: Mx+Ly2+[Al(x+2y)Si1−(x+2y)O2n]·mH2O where M+ and L2+ are monovalent and divalent cations [...]

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