The force-extension relationship of single polymer chains is an essential component underlying the development of macroscopic constitutive models for elastomers. In this work, we present a model for the force-extension relationship beyond the consideration of classical entropic elasticity, by accounting for bond deformation on the chain's backbone. Parameters in this model are mostly molecular parameters for bond stretching, bending, and breaking already available in the literature, thereby limiting the parameters that need to be extracted from fitting experimental data to a minimum. In addition, an extension of the model is made to include the effects of mechanophores: molecules that react under the application of a mechanical force. This has endowed the model with the capability of predicting the mechanophore reaction as well as chain scission. The model is applied and compared to experimental data, in a range of scenarios: reproducing the measured force-extension relationship for PDMS chains, calculating the rate dependent fracture energy of PDMS films, and predicting the force-extension relationship caused by the unfolding of mechanophore domains. For the last example, it was demonstrated that this type of chain has the potential to be utilized to design elastomers with substantially enhanced strength and toughness.
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http://dx.doi.org/10.1021/acs.jpcb.9b09068 | DOI Listing |
Phys Rev E
July 2024
Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA.
Stretching an elastic material along one axis typically induces contraction along the transverse axes, a phenomenon known as the Poisson effect. From these strains, one can compute the specific volume, which generally either increases or, in the incompressible limit, remains constant as the material is stretched. However, in networks of semiflexible or stiff polymers, which are typically highly compressible yet stiffen significantly when stretched, one instead sees a significant reduction in specific volume under finite strains.
View Article and Find Full Text PDFJ Mech Behav Biomed Mater
September 2024
Department of Biomedical Engineering, Yale University, New Haven, CT, USA. Electronic address:
An intricate reciprocal relationship exists between adherent synthetic cells and their extracellular matrix (ECM). These cells deposit, organize, and degrade the ECM, which in turn influences cell phenotype via responses that include sensitivity to changes in the mechanical state that arises from changes in external loading. Collagen-based tissue equivalents are commonly used as simple but revealing model systems to study cell-matrix interactions.
View Article and Find Full Text PDFJ Mech Behav Biomed Mater
July 2024
Department of Health Promotion and Rehabilitation, Lithuanian Sports University, Kaunas, Lithuania.
Skeletal muscle and adipose tissue are characterized by unique structural features finely tuned to meet specific functional demands. In this study, we investigated the passive mechanical properties of soleus (SOL), extensor digitorum longus (EDL) and diaphragm (DIA) muscles, as well as subcutaneous (SAT), visceral (VAT) and brown (BAT) adipose tissues from 13 C57BL/6J mice. Thereto, alongside stress-relaxation assessments we subjected isolated muscles and adipose tissues (ATs) to force-extension tests up to 10% and 30% of their optimal length, respectively.
View Article and Find Full Text PDFVaccine
September 2024
Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases, Immunization Services Division, USA. Electronic address:
When public health experts think of rural barriers to vaccines, they often initially focus on access, which makes sense with a new vaccine during a pandemic. This commentary highlights that there can be more complexity to vaccine uptake in rural communities. What follows are some examples of CDC's efforts to better understand rural health and learnings to inform ongoing vaccination efforts in rural communities.
View Article and Find Full Text PDFJ Mol Graph Model
June 2024
School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran; University of Strasbourg, CNRS, ICUBE Laboratory, Strasbourg, France. Electronic address:
Mechanical properties of proteins that have a crucial effect on their operation. This study used a molecular dynamics simulation package to investigate rubredoxin unfolding on the atomic scale. Different simulation techniques were applied, and due to the dissociation of covalent/hydrogen bonds, this protein demonstrates several intermediate states in force-extension behavior.
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