Supramolecular Fractal Growth of Self-Assembled Fibrillar Networks

Nasr, Pedram; Leung, Hannah; Auzanneau, France‐Isabelle; Rogers, Michael A.

doi:10.3390/gels7020046

Cited by 6 publications

(4 citation statements)

References 72 publications

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“…Transmission electron microscopy (TEM) imaging (see Figure 2C) showed the formation of eADF4(C16) nanofibrils with diameters of 9.0 ± 1.0 nm ( n = 20), indicating fractal fibrillar growth upon protein self‐assembly and consequent gelation. [ 26 ] Liu and Sawant adapted Avrami's equation for the case of time‐dependent fractal growth, replacing n with the fractal dimension D f . [ 27 ] Interestingly, besides the significantly increased rate constant k , a decrease in D f from 2.85 to 2.34 was observed (Figure 2B).…”

Section: Resultsmentioning

confidence: 99%

Rheological and Biological Impact of Printable PCL‐Fibers as Reinforcing Fillers in Cell‐Laden Spider‐Silk Bio‐Inks

Schaefer,

Andrade Mier,

Sonnleitner

et al. 2023

Small Methods

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The development of bio‐inks capable of being 3D‐printed into cell‐containing bio‐fabricates with sufficient shape fidelity is highly demanding. Structural integrity and favorable mechanical properties can be achieved by applying high polymer concentrations in hydrogels. Unfortunately, this often comes at the expense of cell performance since cells may become entrapped in the dense matrix. This drawback can be addressed by incorporating fibers as reinforcing fillers that strengthen the overall bio‐ink structure and provide a second hierarchical micro‐structure to which cells can adhere and align, resulting in enhanced cell activity. In this work, the potential impact of collagen‐coated short polycaprolactone‐fibers on cells after being printed in a hydrogel is systematically studied. The matrix is composed of eADF4(C16), a recombinant spider silk protein that is cytocompatible but non‐adhesive for cells. Consequently, the impact of fibers could be exclusively examined, excluding secondary effects induced by the matrix. Applying this model system, a significant impact of such fillers on rheology and cell behavior is observed. Strikingly, it could be shown that fibers reduce cell viability upon printing but subsequently promote cell performance in the printed construct, emphasizing the need to distinguish between in‐print and post‐print impact of fillers in bio‐inks.

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Section: Resultsmentioning

confidence: 99%

Rheological and Biological Impact of Printable PCL‐Fibers as Reinforcing Fillers in Cell‐Laden Spider‐Silk Bio‐Inks

Schaefer,

Andrade Mier,

Sonnleitner

et al. 2023

Small Methods

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“…Previous studies have reported that two growth modes of gel networks (bulb growth mode and fiber growth mode) can control the gel properties [ 16 ]. The Avrami model has been widely used to analyze the dynamics of small and macromolecular polymers, in which the obtained kinetic parameters are closely related to the growth dimension and the nucleation mechanism, establishing a relationship between dynamics and gel structures [ 17 , 18 ]. According to the difference in the Avrami factor, the process of fiber network structure is studied from one-dimensional growth to the whole fiber network.…”

Section: Introductionmentioning

confidence: 99%

Thermo-/pH-Dual-Sensitive PEG/PAMAM Nanogel: Reaction Dynamics and Plugging Application of CO2 Channeling

Liu

Wang

Shi

et al. 2022

Gels

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Smart hydrogels, owing to their exceptional viscoelastic and deformable capacity in response to environmental stimulation involving temperature and pH, have been successfully applied in oilfields for purposes such as water and/or gas shutoff treatments. However, the CO2 breakthrough problem in low permeability reservoirs has not been well solved. In this work, a rheological method-based Avrami dynamics model and Dickinson dynamics model were employed to investigate the dynamic gelation process of thermo-/pH-dual-sensitive PEG/PAMAM nanogels to further our understanding of the microstructure of their gelation and pertinence plugging application. Plugging experiments were performed by alternating injections of CO2 and hydrogel solution in a slug type on three fractured low permeability cores with a backpressure of 13 MPa. The nanogels presented a secondary growth pattern from three to one dimension from micrometer to nanometer size with a morphological transformation from a sphere to an irregular ellipsoid or disk shape. The phase transition temperature was 50 °C, and the phase transition pH was 10. If both or either were below these values, the hydrogel swelled; otherwise, it shrank. Plugging results show that the plugging efficiency was higher than 99%. The maximum breakthrough pressure was 19.93 MPa, and the corresponding residual pressure remained 17.64 MPa for a 10 mD core, exhibiting great plugging performance and high residual resistance after being broken through by CO2.

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“…This fact has inspired a variety of applications of the Avrami model that have stretched far beyond the process of crystallization. Some examples include: gelation [3][4][5], the adsorption of solutes [6][7][8] and…”

Section: Introductionmentioning

confidence: 99%

Problems with Applying the Ozawa–Avrami Crystallization Model to Non-Isothermal Crosslinking Polymerization

Vyazovkin

Galukhin

2022

Polymers

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Ozawa has modified the Avrami model to treat non-isothermal crystallization kinetics. The resulting Ozawa–Avrami model yields the Avrami index (n) and heating/cooling function (χ(T)). There has been a number of recent applications of the Ozawa–Avrami model to non-isothermal crosslinking polymerization (curing) kinetics that have determined n and have used χ(T) in place of the rate constant (k(T)) in the Arrhenius equation to evaluate the activation energy (E) and the preexponential factor (A). We analyze this approach mathematically as well as by using simulated and experimental data, highlighting the following problems. First, the approach is limited to the processes that obey the Avrami model. In cases of autocatalytic or decelerating kinetics, commonly encountered in crosslinking polymerizations, n reveals a systematic dependence on temperature. Second, χ(T) has a more complex temperature dependence than k(T) and thus cannot produce exact values of E and A via the Arrhenius equation. The respective deviations can reach tens or even hundreds of percent but are diminished dramatically using the heating/cooling function in the form [χ(T)]1/n. Third, without this transformation, the Arrhenius plots may demonstrate breakpoints that leads to questionable interpretations. Overall, the application of the Ozawa–Avrami model to crosslinking polymerizations appears too problematic to be justified, especially considering the existence of well-known alternative kinetic techniques that are flexible, accurate, and computationally simple.

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Supramolecular Fractal Growth of Self-Assembled Fibrillar Networks

Cited by 6 publications

References 72 publications

Rheological and Biological Impact of Printable PCL‐Fibers as Reinforcing Fillers in Cell‐Laden Spider‐Silk Bio‐Inks

Rheological and Biological Impact of Printable PCL‐Fibers as Reinforcing Fillers in Cell‐Laden Spider‐Silk Bio‐Inks

Thermo-/pH-Dual-Sensitive PEG/PAMAM Nanogel: Reaction Dynamics and Plugging Application of CO2 Channeling

Problems with Applying the Ozawa–Avrami Crystallization Model to Non-Isothermal Crosslinking Polymerization

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