scholarly journals Physical Interactions Strengthen Chemical Gelatin Methacryloyl Gels

Gels ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 4 ◽  
Author(s):  
Lisa Rebers ◽  
Tobias Granse ◽  
Günter Tovar ◽  
Alexander Southan ◽  
Kirsten Borchers
Keyword(s):  
Network Formation ◽  
Sol Gel ◽  
Solution Viscosity ◽  
Cross Linking ◽  
Physical Network ◽  
Helix Formation ◽  
Triple Helix Formation ◽  
Sol Gel Transition ◽  
And Control ◽  
Chemical Cross Linking

Chemically cross-linkable gelatin methacryloyl (GM) derivatives are getting increasing attention regarding biomedical applications. Thus, thorough investigations are needed to achieve full understanding and control of the physico-chemical behavior of these promising biomaterials. We previously introduced gelatin methacryloyl acetyl (GMA) derivatives, which can be used to control physical network formation (solution viscosity, sol-gel transition) independently from chemical cross-linking by variation of the methacryloyl-to-acetyl ratio. It is known that temperature dependent physical network formation significantly influences the mechanical properties of chemically cross-linked GM hydrogels. We investigated the temperature sensitivity of GM derivatives with different degrees of modification (GM2, GM10), or similar degrees of modification but different methacryloyl contents (GM10, GM2A8). Rheological analysis showed that the low modified GM2 forms strong physical gels upon cooling while GM10 and GM2A8 form soft or no gels. Yet, compression testing revealed that all photo cross-linked GM(A) hydrogels were stronger if cooling was applied during hydrogel preparation. We suggest that the hydrophobic methacryloyl and acetyl residues disturb triple helix formation with increasing degree of modification, but additionally form hydrophobic structures, which facilitate chemical cross-linking.

Fractal Growth During Gelation

1992 ◽  
Vol 271 ◽  
Author(s):  
Edward J. A. Pope
Keyword(s):  
New Technology ◽  
Sol Gel ◽  
Silica Gels ◽  
Solution Viscosity ◽  
Fractal Growth ◽  
Index Changes ◽  
Sol Gel Transition ◽  
And Control ◽  
Gel Processing ◽  
Multi Component System

ABSTRACTSol-gel processing has emerged as an important new technology for the fabrication of a wide variety of glass, ceramic, and composite materials. In order to better understand and control the gelation process, a theoretical model has been developed which quantitatively links features of fractal growth with measurable properties of a solution during the sol-gel transition. The result of that effort is the fractal growth model of gelation (FGMG) which expresses the solution viscosity, light scattering, and refractive index changes as a funtion of time and the fractal dimension. In this paper, the application of FGMG to silica gels and multi-component system, such as titanium aluminosilicates, is presented.

scholarly journals Self-Healing Hydrogels with both LCST and UCST through Cross-Linking Induced Thermo-Response

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 490 ◽  
Author(s):  
Haifeng Zhao ◽  
Heng An ◽  
Baozhong Xi ◽  
Yan Yang ◽  
Jianglei Qin ◽  
...  
Keyword(s):  
Sol Gel ◽  
Covalent Bond ◽  
The Self ◽  
Solution Temperature ◽  
Cross Linking ◽  
Self Healing ◽  
Critical Solution Temperature ◽  
Upper Critical Solution Temperature ◽  
Healing Property ◽  
Sol Gel Transition

Self-healing hydrogels have drawngreat attention in the past decade since the self-healing property is one of the characteristics of living creatures. In this study, poly(acrylamide-stat-diacetone acrylamide) P(AM-stat-DAA) with a pendant ketone group was synthesized from easy accessible monomers, and thermo-responsive self-healing hydrogels were prepared through a series of diacylhydrazide compounds cross-linking without any additional stimulus. Although the copolymers do not show thermo-response, the hydrogels became thermo-responsive andboth the lower critical solution temperature (LCST) and upper critical solution temperature (UCST) varied with the composition of the copolymer and structure of cross-linkers. With a dynamic covalent bond connection, the hydrogel showed gel-sol-gel transition triggered by acidity, redox, and ketone to acylhydrazide group ratios. This is another interesting cross-linking induced thermo-responsive (CIT) hydrogel with different properties compared to PNIPAM-based thermo-responsive hydrogels. The self-healing hydrogel with CIT properties could have great potential for application in areas related to bioscience, life simulation, and temperature switching.

Characterization of Cross-Linked Two-Phase Acrylic Polymers

1976 ◽  
Vol 55 (3) ◽  
pp. 452-459 ◽  
Author(s):  
R.P. Kusy ◽  
B.J. Lytwyn ◽  
D.T. Turner
Keyword(s):  
Sol Gel ◽  
Dental Materials ◽  
Solution Viscosity ◽  
Cross Linking ◽  
Particulate Phase ◽  
Quantitative Microscopy ◽  
Two Phase ◽  
Acrylic Polymers ◽  
Equilibrium Swelling

Dental materials were made from mixtures of acrylic particles and a cross-linking monomer. The resulting two-phase polymers were characterized by quantitative microscopy. Components were analyzed by measurements of sol-gel partition, solution viscosity, and equilibrium swelling. A cross-linked network formed in the particulate phase only after slow polymerization.

scholarly journals Analysis of the Effect of Processing Conditions on Physical Properties of Thermally Set Cellulose Hydrogels

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1066 ◽  
Author(s):  
Tim Huber ◽  
Sean Feast ◽  
Simone Dimartino ◽  
Wanwen Cen ◽  
Conan Fee
Keyword(s):  
Mechanical Properties ◽  
Network Formation ◽  
Aqueous Sodium Hydroxide ◽  
Cross Linking ◽  
Processing Conditions ◽  
Hot Press ◽  
Thermal Gelation ◽  
Complex Shapes ◽  
Bond Network ◽  
Chemical Cross Linking

Cellulose-based hydrogels were prepared by dissolving cellulose in aqueous sodium hydroxide (NaOH)/urea solutions and casting it into complex shapes by the use of sacrificial templates followed by thermal gelation of the solution. Both the gelling temperatures used (40–80 °C), as well as the method of heating by either induction in the form of a water bath and hot press or radiation by microwaves could be shown to have a significant effect on the compressive strength and modulus of the prepared hydrogels. Lower gelling temperatures and shorter heating times were found to result in stronger and stiffer gels. Both the effect of physical cross-linking via the introduction of additional non-dissolving cellulosic material, as well as chemical cross-linking by the introduction of epichlorohydrin (ECH), and a combination of both applied during the gelation process could be shown to affect both the mechanical properties and microstructure of the hydrogels. The added cellulose acts as a physical-cross-linking agent strengthening the hydrogen-bond network as well as a reinforcing phase improving the mechanical properties. However, chemical cross-linking of an unreinforced gel leads to unfavourable bonding and cellulose network formation, resulting in drastically increased pore sizes and reduced mechanical properties. In both cases, chemical cross-linking leads to larger internal pores.

scholarly journals Design and synthesis of the novel cross-linking reagents triggered by the triple helix formation

2000 ◽  
Vol 44 (1) ◽  
pp. 39-40 ◽  
Author(s):  
F. Nagatsugi ◽  
D. Usui ◽  
T. Kawasaki ◽  
M. Maeda ◽  
S. Sasaki
Keyword(s):  
Triple Helix ◽  
Cross Linking ◽  
The Novel ◽  
Design And Synthesis ◽  
Helix Formation ◽  
Triple Helix Formation

Simultaneous Sheet Cross-Linking and Deoxygenation in the Graphene Oxide Sol–Gel Transition

2014 ◽  
Vol 118 (49) ◽  
pp. 28855-28860 ◽  
Author(s):  
Anna P. Goldstein ◽  
William Mickelson ◽  
Ariella Machness ◽  
Gloria Lee ◽  
Marcus A. Worsley ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Sol Gel ◽  
Cross Linking ◽  
Sol Gel Transition ◽  
Gel Transition

Modeling of Sol-Gel Transition with Loop Network Formation and its Implications on Mechanical Properties

2001 ◽  
Vol 677 ◽  
Author(s):  
Hang-Shing Ma ◽  
Jean-H. Prévost ◽  
Rémi Jullien ◽  
George W. Scherer
Keyword(s):  
Network Formation ◽  
Sol Gel ◽  
Weak Links ◽  
Loop Structure ◽  
Linear Elastic ◽  
Diffusion Limited ◽  
Scaling Relationship ◽  
Loop Network ◽  
Sol Gel Transition ◽  
Gel Transition

ABSTRACTCertain classes of sol-gel transition have been modeled as diffusion-limited cluster-cluster aggregation (DLCA), but it produces excessive dangling branches on the resulting network that underestimates the rigidity of gels. The “dangling bond deflection” (DEF) model was developed to simulate spatial fluctuation of the dangling branches under thermal energy. Collision and sticking of two dangling branches within the same cluster turns these branches into a loop. Combination of the DLCA and DEF models creates network that possesses extensive loop structure and negligible dangling mass. The networks are substantially stiffened by the loop structure, and successfully reproduce the empirical scaling relationship between linear elastic modulus and density exhibited by real aerogels. The gel structure can be represented by the “blob-and-link” model, in which blobs refer to dense, rigid collections of particles, interconnected by tenuous links of particle chains. When the network is deformed, only these few weak links contribute to the stiffness, leaving the blobs unstrained. The gel modulus drops significantly as porosity increases because more particles reside in the blobs and fewer particles carry the strain.

The sol–gel transition of ultra-low solid content TEMPO-cellulose nanofibril/mixed-linkage β-glucan bionanocomposite gels

Soft Matter ◽  
2018 ◽  
Vol 14 (46) ◽  
pp. 9393-9401 ◽  
Author(s):  
Suvi Arola ◽  
Mahmoud Ansari ◽  
Antti Oksanen ◽  
Elias Retulainen ◽  
Savvas G. Hatzikiriakos ◽  
...  
Keyword(s):  
Plant Cell Wall ◽  
Sol Gel ◽  
Cellulose Nanofibrils ◽  
Solid Content ◽  
Cross Linking ◽  
Cell Wall Polysaccharide ◽  
Oxidized Cellulose ◽  
Cellulose Nanofibril ◽  
Sol Gel Transition ◽  
Gel Transition

Ultra-low solid content gels were prepared by physically cross-linking TEMPO-oxidized cellulose nanofibrils (TEMPO-CNF) with the plant-cell-wall polysaccharide, mixed-linkage β-glucan (MLG).

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