Role of Crosslinking and Entanglements in the Mechanics of Silicone Networks

Babu, Anju R.; Gundiah, Namrata

doi:10.1007/s11340-014-9895-x

Cited by 25 publications

(16 citation statements)

References 18 publications

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“…For homogeneous isotropic linear elastic materials, Young's modulus can be derived as E = 2•(1 + ν)•G′. Since Poisson's modulus of our PDMS is ν = 0.418 37 , we estimate E = 19.2kPa when deformed at 1 Hz. This global value matches the results of 5 mechanical profiles obtained by atomic force microscopy, as the local Young's modulus obtained away from a pillar is E = 20.3 ± 2 kPa (Fig.…”

Section: Resultsmentioning

confidence: 99%

Magneto-Active Substrates for Local Mechanical Stimulation of Living Cells

Coullomb

Bidan

Fratzl

et al. 2018

Biophysical Journal

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Cells are able to sense and react to their physical environment by translating a mechanical cue into an intracellular biochemical signal that triggers biological and mechanical responses. This process, called mechanotransduction, controls essential cellular functions such as proliferation and migration. The cellular response to an external mechanical stimulation has been investigated with various static and dynamic systems, so far limited to global deformations or to local stimulation through discrete substrates. To apply local and dynamic mechanical constraints at the single cell scale through a continuous surface, we have developed and modelled magneto-active substrates made of magnetic micro-pillars embedded in an elastomer. Constrained and unconstrained substrates are analysed to map surface stress resulting from the magnetic actuation of the micro-pillars and the adherent cells. These substrates have a rigidity in the range of cell matrices, and the magnetic micro-pillars generate local forces in the range of cellular forces, both in traction and compression. As an application, we followed the protrusive activity of cells subjected to dynamic stimulations. Our magneto-active substrates thus represent a new tool to study mechanotransduction in single cells, and complement existing techniques by exerting a local and dynamic stimulation, traction and compression, through a continuous soft substrate.Living cells have a sense of touch, which means that they are able to feel, respond and adapt to the mechanical properties of their environment. The process by which cells convert mechanical signals into biochemical signals is called mechanotransduction. Defects in the mechanotransduction pathways are implicated in numerous diseases ranging from atherosclerosis and osteoporosis to cancer progression and developmental disorders 1,2 . Since the 1990s, different static studies focused on mechanosensing have shown that cells can migrate along the rigidity gradient direction 3 and that stem cells can differentiate in vitro according to their substrate's stiffness 4 and geometry 5 . The interplay between a mechanical force and the reinforcement of cell adhesion has also been documented 6,7 . In their natural environment, cells face a complex and dynamic mechanical environment. Cyclic strain can induce reorientation of adherent cells and affect cell growth depending on the temporal and spatial properties of the mechanical stimulation [8][9][10][11] . The relevant timescales span from the milli-second for the stretching of mechanosensitive proteins, minutes for mechanotransduction signalling to hours for global morphological changes and even longer for adapting cell functions 12 . Taken together, previous works have shown that cells are sensitive to both the spatial and temporal signatures of mechanical stimuli. In order to study mechanotransduction, it is thus essential to stimulate cells with mechanical cues controlled both spatially and temporally.To address this topic, various methods have been proposed to exert experim...

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Section: Resultsmentioning

confidence: 99%

Magneto-Active Substrates for Local Mechanical Stimulation of Living Cells

Coullomb

Bidan

Fratzl

et al. 2018

Biophysical Journal

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“…For homogeneous isotropic linear elastic materials, Young’s modulus can be derived as E = 2·(1+v)-G’. Since Poisson’s modulus of our PDMS is v = 0.418 36 , we estimate E = 19.2kPa when deformed at 1Hz. This global value matches the results of 5 mechanical profiles obtained by atomic force microscopy, as the local Young’s modulus obtained away from a pillar is E = 20.3 ± 2 kPa (Fig.2A).…”

Section: Resultsmentioning

confidence: 99%

Magneto-active substrates for local mechanical stimulation of living cells

Bidan

Fratzl

Coullomb

et al. 2017

Preprint

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“…[ 10 ] Decreasing the crosslink density results in a decrease in the modulus. [ 47,48 ] The modulus, elongation, and hardness increase with increasing crosslink density. [ 10,41 ] Irregularities in the structure after crosslinking cause deviations in the physical behavior.…”

Section: Methodsmentioning

confidence: 99%

A review of liquid silicone rubber injection molding: Process variables and process modeling

Bont

Barry

Johnston

2021

Polymer Engineering & Sci

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Liquid silicone rubber (LSR) is an elastomer molded into critical performance components for applications in medical, power, consumer, automotive, and aerospace applications. This article reviews process behavior, material modeling, and simulation of the (LSR) injection molding process. Each phase of the LSR injection molding process is discussed, including resin handling, plastication, injection, pack and hold, and curing; and factors affecting the molding process are reviewed. Processing behavior of LSR is marked by transient interactions between curing, shear rate, temperature, pressure, and tooling. Therefore, current LSR models for curing, viscosity, pressure, and temperature are discussed. Process dynamics and material modeling are combined in LSR injection molding simulations with applications in mold design, troubleshooting process‐induced defects, and management of shear stress and non‐uniform temperatures between LSR and substrates during overmolding. Finally, case studies using commercial simulation software are presented, which have shown cavity pressure and flow front advancement within 3% of experimental values. Optimization of LSR materials, data collection, model fitting, venting, and bonding remain areas of continued interest.

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Role of Crosslinking and Entanglements in the Mechanics of Silicone Networks

Cited by 25 publications

References 18 publications

Magneto-Active Substrates for Local Mechanical Stimulation of Living Cells

Magneto-Active Substrates for Local Mechanical Stimulation of Living Cells

Magneto-active substrates for local mechanical stimulation of living cells

A review of liquid silicone rubber injection molding: Process variables and process modeling

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