Elastocaloric effect in amorphous polymer networks undergoing mechanotropic phase transitions

The eukaryotic cytoskeleton is a protein fibre network mainly consisting of the semi-flexible biopolymer F-actin, microtubules and intermediate filaments. It is well known to exhibit a pronounced structural polymorphism, which enables intracellular processes such as cell adhesion, cell motility and cell division. We present a computational study on cross-linked networks of semi-flexible polymers, which offers a detailed analysis of the network structure and phase transitions from one morphology to another. We elaborate the morphological differences, their mechanical implications and the order of the observed phase transitions. Finally, we present a perspective on how the information gained in our simulations can be exploited in order to build both flexible and accurate, microstructurally informed, homogenized constitutive models of the cytoskeleton.

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Ability to Control the Glass Transition Temperature of Amorphous Shape-Memory Polyesterurethane Networks by Varying Prepolymers in Molecular Mass as well as in Type and Content of Incorporated Comonomers

MRS Proceedings ◽

10.1557/proc-1190-nn01-09 ◽

2009 ◽

Vol 1190 ◽

Author(s):

Joerg Zotzmann ◽

Steffen Kelch ◽

Armin Alteheld ◽

Marc Behl ◽

Andreas Lendlein

Keyword(s):

Glass Transition ◽

Minimally Invasive Surgery ◽

Shape Memory ◽

Molecular Mass ◽

Amorphous Polymer ◽

Polymer Networks ◽

Precise Control ◽

Low Weight ◽

Switching Temperature ◽

Selection Of

AbstractThe need of intelligent implant materials for applications in the area of minimally invasive surgery leads to tremendous attention for polymers which combine degradability and shape-memory capability. Application of heat, and thereby exceeding a certain switching temperature Tsw, causes the device to changes its shape. The precise control of Tsw is particularly challenging. It was investigated in how far Tg, that can be used as Tsw, of amorphous polymer networks from star-shaped polyester macrotetrols crosslinked with a low-weight linker can be controlled systematically by incorporation of different comonomers into poly(rac-lactide) prepolymers. The molecular mass of the prepolymers as well as type and content of the comonomers was varied. The Tg could be adjusted by selection of comonomer type and ratio without affecting the advantageous elastic properties of the polymer networks.

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Structure and Mechanical Properties of Rubberlike Proteins in Animals

Rubber Chemistry and Technology ◽

10.5254/1.3536137 ◽

1987 ◽

Vol 60 (3) ◽

pp. 417-438 ◽

Cited By ~ 28

Author(s):

John M. Gosline

Keyword(s):

Amorphous Polymer ◽

Polymer Networks ◽

Random Coil ◽

Future Research ◽

Random Networks ◽

Glass Transitions ◽

Mechanical State ◽

Protein Molecules ◽

Polypeptide Chains ◽

Covalent Crosslinks

Abstract Polymer networks formed from protein molecules that adopt kinetically-free, random-coil conformations are found in many animals, where they play a number of important roles. The 5 rubberlike proteins isolated and studied to date indicate that animal rubbers, like their synthetic counterparts, contain random networks which are usually stabilized by covalent crosslinks. Long-range elasticity in rubberlike proteins is based on changes in the conformational entropy of random-coil molecules. Further, these protein networks show viscoelastic glass transitions similar to all other amorphous polymer networks. Future research on protein sequences should increase our understanding of how polypeptide chains can function as random-coil molecules, and studies into the mechanical state of elastin in arterial tissues may provide important clues about the mechanisms of some forms of human disease.

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Conversion of amorphous polymer networks to covalent organic frameworks under ionothermal conditions: a facile synthesis route for covalent triazine frameworks

Journal of Materials Chemistry A ◽

10.1039/c5ta07408h ◽

2015 ◽

Vol 3 (48) ◽

pp. 24422-24427 ◽

Cited By ~ 50

Author(s):

Sophie Kuecken ◽

Johannes Schmidt ◽

Linjie Zhi ◽

Arne Thomas

Keyword(s):

Amorphous Polymer ◽

Polymer Networks ◽

Porous Polymer ◽

Covalent Organic Frameworks ◽

Facile Synthesis ◽

Synthesis Route

Covalent triazine frameworks (CTFs) are prepared from amorphous, non-porous polymer networks using a facile and scalable procedure.

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Elastic and ultimate behavior of amorphous polymer networks

Journal of Macromolecular Science Part B ◽

10.1080/00222347108212534 ◽

1971 ◽

Vol 5 (2) ◽

pp. 269-271 ◽

Cited By ~ 3

Author(s):

H. H. Kausch-Blecken von Schmeling

Keyword(s):

Amorphous Polymer ◽

Polymer Networks

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Elastocaloric signature of nematic fluctuations

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2105911118 ◽

2021 ◽

Vol 118 (37) ◽

pp. e2105911118

Author(s):

Matthias S. Ikeda ◽

Thanapat Worasaran ◽

Elliott W. Rosenberg ◽

Johanna C. Palmstrom ◽

Steven A. Kivelson ◽

...

Keyword(s):

Phase Transitions ◽

Critical Temperature ◽

Transport Properties ◽

Order Parameter ◽

Low Energy ◽

Elastic Coupling ◽

Doping Dependence ◽

Elastocaloric Effect ◽

Thermodynamic And Transport Properties

The elastocaloric effect (ECE) relates changes in entropy to changes in strain experienced by a material. As such, ECE measurements can provide valuable information about the entropy landscape proximate to strain-tuned phase transitions. For ordered states that break only point symmetries, bilinear coupling of the order parameter with strain implies that the ECE can also provide a window on fluctuations above the critical temperature and hence, in principle, can also provide a thermodynamic measure of the associated susceptibility. To demonstrate this, we use the ECE to sensitively reveal the presence of nematic fluctuations in the archetypal Fe-based superconductor Ba(Fe1−xCox)2As2. By performing these measurements simultaneously with elastoresistivity in a multimodal fashion, we are able to make a direct and unambiguous comparison of these closely related thermodynamic and transport properties, both of which are sensitive to nematic fluctuations. As a result, we have uncovered an unanticipated doping dependence of the nemato-elastic coupling and of the magnitude of the scattering of low-energy quasi-particles by nematic fluctuations—while the former weakens, the latter increases dramatically with increasing doping.

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