Incorporation of photo-responsive molecules in soft matter provides new opportunities to develop materials with actuation behavior that have applications in artificial muscles and soft robotics. We designed a hybrid material in which peptide amphiphile (PA) nanofibers functionalized with photo-responsive polymers can enhance the mechanical stability and actuation kinetics of the hydrogel. In this work, we developed a computational model and performed molecular dynamics simulations to study how light as a stimulus can change the molecular structure of hybrid PA-polymer systems. Our coarse-grained model based on Martini force field can successfully capture the results obtained in the experiments in addition to explaining the role of PA nanofibers in the actuation process. With a very small difference in the two isomers of spiropyran, we can observe the changes in volume of the hydrogel under light (SP) and dark (MC) conditions. We also show that the peptide amphiphile nanofibers improve actuation kinetics by lowering the energy barrier during the contraction of the hydrogel using free energy calculations.

Supramolecular peptide amphiphile-polymeric hybrid hydrogels for photo-actuation: Modeling and simulation

2019 Spring National Meeting

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