scholarly journals Thermo/Shear-Responsive Injectable Hydrogels from an Alginate/PNIPAM-Based Graft Copolymer: Effect of Divalent Cations Ca2+

Proceedings ◽  
2020 ◽  
Vol 69 (1) ◽  
pp. 28
Author(s):  
Sofia-Falia Saravanou ◽  
Fotoula Kounelaki ◽  
Constantinos Tsitsilianis
Keyword(s):  
Graft Copolymer ◽  
Divalent Cations ◽  
Side Chains ◽  
Tertiary Butyl ◽  
Physiological Temperature ◽  
Aqueous Polymer ◽  
Self Assembling ◽  
Weak Gel ◽  
Rheological Experiments ◽  
Soft Gels

This work is focused on the design and development of biocompatible self-assembling hydrogels, which behave as soft gels at room temperature and strong gels at the physiological temperature, suitable for potential bio-applications. A graft copolymer of sodium-alginate, bearing eight side chains of poly(N-isopropylacrylamide), enriched with the hydrophobic comonomer N-tertiary-butyl-acrylamide (NtBAM), (NaALG-g-P(NIPAM-co-NtBAM)) were used as gelator. In total, 5 wt% aqueous polymer solutions in the presence of Ca2+ cations were prepared and evaluated as thermo-responsive hydrogels. Rheological experiments revealed a twostep reversible gelation either upon heating or cooling. The divalent cations operated as a cross-linking agent through ionic interactions, inducing the formation of a network at low temperatures. Upon heating, an additional crosslinking develops through thermo-induced hydrophobic association of the thermo-responsive P(NIPAM-co-NtBAM) side chains above a critical temperature. The combination of thermo- and shear-responsiveness provides shelf-assembling systems as potential candidates for injectable strategies. For instance, the system under investigation could be used for cell transplantation, which requires a weak gel to protect the cells during injection and a gel strengthening after the injection at a physiological temperature to immobilize the created scaffold in the targeting position of the host tissue.

Synthesis and characterization of amphiphilic graft copolymers with hydrophobic poly(α-methylstyrene) backbone and hydrophilic poly(n-vinylpyrrolidone) side chains

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Fatima Zohra Sebba ◽  
Seghier Ould Kada ◽  
Mohamed Benaicha ◽  
Nerjesse Nemiche
Keyword(s):  
Graft Copolymer ◽  
Graft Copolymers ◽  
Radical Copolymerization ◽  
Side Chains ◽  
Free Radical Copolymerization ◽  
Good Efficiency ◽  
Molecular Weights ◽  
Grafting Reaction ◽  
Viscosity Variation ◽  
End Capping

AbstractIn this study, 2-oxopropylmethacrylate-terminated poly(N-vinyl-2- pyrrolidone) is produced by cationic polymerization using HClO4 as an initiator. Termination (end capping) step is accomplished using 2- hydroxypropylmethacrylate (2HPMA) and the polymer product has different chain lengths of molecular weight averages ranging from 672 to 3049 g/mol. The study also synthesised amphipathic graft copolymers having hydrophobic poly(α- methylstyrene) as a backbone chain and hydrophilic poly(N-vinyl-2-pyrrolidone) (PVP) as side chains of various lengths. The copolymer synthesis was accomplished by free radical copolymerization of ω-oxopropylmethacrylate PVP in the presence of α-methyl styrene initiated with benzoyl peroxide. Measurements of the dynamic viscosity of the polymer solution (20% weight of macromonomers in ethanol) show that the viscosity is proportional to the average molecular weights M̅n . However, a reverse behaviour of the viscosity variation with regard to M̅n is observed for graft copolymer samples. The viscosity variation with respect to the graft copolymer mass must be due to steric effects, which are strongly pronounced in grafted copolymer chains. Appearance of the number of side chains attached to poly(α-methylstyrene) backbone reveals that the grafting reaction has occurred with good efficiency.

Spinning of Fibers from Graft Copolymers of Polyacrylonitrile and Poly(Methyl Acrylate)

1976 ◽  
Vol 46 (2) ◽  
pp. 77-81 ◽  
Author(s):  
Samy Abdel Monem El-Garf
Keyword(s):  
Graft Copolymer ◽  
Methyl Acrylate ◽  
Graft Copolymers ◽  
Coagulation Bath ◽  
Side Chains ◽  
Initial Value

Fibers were spun from graft copolymers of polyacrylonitrile and poly(methyl acrylate). Increasing poly(methyl acrylate) side chains from 5 to 8% decreased the viscosity of the spinning solution in dimethylformamide. The spinning solutions were unstable. When the graft copolymer contained 5% side chains, the viscosity of these solutions returned to almost its initial value by heating. Fibers were obtained from graft copolymers containing from 5–13% poly(methyl acrylate) side chains. These were formed at the temperature of the coagulation bath (50°C), while at temperatures less than 50°C the fibers were not obtained. Weak fibers were produced from a graft copolymer containing 13% side chains at the temperatures of the coagulation bath (20 and 50°C). No fibers were obtained from graft copolymer containing 25% side chains. The method of dissolution of the graft copolymers does affect the drawing of fibers produced from them. It was observed that the heating of the spinning solution decreases the amount of drawing of the produced fibers. The presence of the flexible side chains of poly(methyl acrylate) in the graft copolymer improves the maximum possible degree of drawing of the fibers relative to that of fibers from the initial linear copolymer and homopolyacrylonitrile.

The Effect of a Method of Dissolution of Graft Copolymer of Polyacrylonitrile and Poly(Methyl Acrylate) on Drawability and Properties of Spun Fibers

1976 ◽  
Vol 46 (10) ◽  
pp. 767-770
Author(s):  
Samy Abdel Monem El-Garf
Keyword(s):  
Graft Copolymer ◽  
Methyl Acrylate ◽  
Modulus Of Elasticity ◽  
Abrasion Resistance ◽  
Side Chains ◽  
Yarn Strength ◽  
Dissolution Temperature ◽  
Initial Modulus ◽  
Spun Fibers

It was found that dissolution of the graft copolymer has an effect on drawability and other properties of fibers spun from this graft copolymer. The resistance to double bending and abrasion resistance are considerably decreased with the increase of the dissolution temperature. The breaking properties were not greatly changed. The maximum loop and knotted yarn strength was reached when the polymer was dissolved by heating. These values are 100% and 99% of the original, respectively—higher than those obtained from PAN and PANM. The presence of 5% PMA in the side chains of the graft copolymer increased the flexibility of these chains. This is evident from the decrease of the initial modulus of elasticity from the values obtained for PANM and PAN.

Enhanced Photocatalytic Reduction of Methyl Viologen by Self-Assembling Ruthenium(II)Poly(Pyridyl) Complexes withL-Lysine Containing Side Chains

2002 ◽  
Vol 106 (16) ◽  
pp. 4227-4231 ◽  
Author(s):  
Masahiro Suzuki ◽  
Chad C. Waraksa ◽  
Thomas E. Mallouk ◽  
Hiroko Nakayama ◽  
Kenji Hanabusa
Keyword(s):  
Methyl Viologen ◽  
Photocatalytic Reduction ◽  
Side Chains ◽  
Self Assembling

Influence of amino acid side chains on the formation of two component self-assembling nanofibrous hydrogels

2017 ◽  
Vol 41 (3) ◽  
pp. 1229-1234 ◽  
Author(s):  
Srinivasa Rao Nelli ◽  
Jhong-Hua Lin ◽  
Thi Ngoc Anh Nguyen ◽  
Dion Tzu-Huan Tseng ◽  
Satish Kumar Talloj ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Derivatives ◽  
Side Chains ◽  
Self Assembling ◽  
Two Component ◽  
Amino Acid Side Chains

Supramolecular co-assembly of amino acid derivatives capped with NDI and Py moieties undergoing supramolecular hydrogelation was developed.

Genetic Exchange Leading to Self-Assembling RNA Species upon Encapsulation in Artificial Protocells

2007 ◽  
Vol 13 (3) ◽  
pp. 279-289 ◽  
Author(s):  
Sergio-Francis M. Zenisek ◽  
Eric J. Hayden ◽  
Niles Lehman
Keyword(s):  
Self Assembly ◽  
Divalent Cations ◽  
Direct Interaction ◽  
Living Systems ◽  
Oil Emulsion ◽  
Rna Molecules ◽  
Self Assembling ◽  
Assembly Pathway ◽  
Water In Oil Emulsion ◽  
Recombination Reactions

The encapsulation of information-bearing macromolecules inside protocells is a critical step in scenarios for the origins of life on the Earth as well as for the construction of artificial living systems. For these protocells to emulate life, they must be able to transmit genetic information to other cells. We have used a water-in-oil emulsion system to simulate the compartmentalization of catalytic RNA molecules. By exploiting RNA-directed recombination reactions previously developed in our laboratory, including a ribozyme self-assembly pathway, we demonstrate that it is possible for information to be exchanged among protocells. This can happen either indirectly by the passage of divalent cations through the inter-protocellular medium (oil), or by the direct interaction of two or more protocells that allows RNA molecules to be exchanged. The degree of agitation affects the ability of such exchange. The consequences of these results include the implications that prototypical living systems can transmit information among compartments, and that the environment can regulate the extent of this crosstalk.

Construction of semi-fluorinated amphiphilic graft copolymer bearing a poly(2-methyl-1,4-bistrifluorovinyloxybenzene) backbone and poly(ethylene glycol) side chains via the grafting-onto strategy

RSC Advances ◽  
2015 ◽  
Vol 5 (50) ◽  
pp. 39668-39676 ◽  
Author(s):  
Guolin Lu ◽  
Hao Liu ◽  
Haifeng Gao ◽  
Chun Feng ◽  
Yongjun Li ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Graft Copolymer ◽  
Graft Copolymers ◽  
Side Chains ◽  
Poly Ethylene Glycol ◽  
Amphiphilic Graft Copolymer ◽  
Amphiphilic Graft Copolymers ◽  
Poly Ethylene ◽  
Williamson Reaction ◽  
Grafting Onto

Amphiphilic graft copolymers bearing a hydrophobic PMBTFVB backbone and hydrophilic PEG side chains were synthesized by Williamson reaction through the grafting-onto strategy.

scholarly journals Ultra-large sheet formation by 1D to 2D hierarchical self-assembly of a “rod–coil” graft copolymer with a polyphenylene backbone

2016 ◽  
Vol 7 (6) ◽  
pp. 1234-1238 ◽  
Author(s):  
Yinjuan Huang ◽  
Rui Yuan ◽  
Fugui Xu ◽  
Yiyong Mai ◽  
Xinliang Feng ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Graft Copolymer ◽  
Self Assembly ◽  
Side Chains ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Large Sheet

This study presents a unique ultra-large sheet formation through 1D to 2D hierarchical self-assembly of a rod–coil graft copolymer containing a rigid polyphenylene backbone tethered with flexible poly(ethylene oxide) side chains.

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