Biological Materials Science: LIVESTREAMED SESSION: Biological Materials Science V
Sponsored by: TMS Functional Materials Division, TMS: Biomaterials Committee
Program Organizers: David Restrepo, University of Texas at San Antonio; Steven Naleway, University of Utah; Jing Du, Pennsylvania State University; Ning Zhang, Baylor University; Hannes Schniepp, William & Mary

Wednesday 8:30 AM
March 2, 2022
Room: 204B
Location: Anaheim Convention Center

Session Chair: David Restrepo, The University of Texas at San Antonio; Jing Du, Penn State University

8:30 AM  
Cellulose-hemicellulose-lignin Interaction in Coconut Endocarp: Sharmi Mazumder1; Ning Zhang1; 1The University of Alabama
    Coconut endocarp is a lightweight biomaterial, simultaneously strong, tough, stiff and hard. A quantitative understanding of the mechanisms enabling the coconut endocarp’s extraordinary mechanical function remains lacking. By means of molecular dynamics and density functional theory (DFT) techniques, this work aims at revealing the nanoscale cellulose-hemicellulose-lignin interaction, which may significantly influence the mechanical properties of coconut endocarp. Uniaxial tension and shear simulations are carried out. Simulation results show that the maximum tensile and shear strengths are obtained in the sandwiched model of cellulose-hemicellulose-lignin-cellulose. Breaking and re-formation of hydrogen bonds on the interfaces between polymer chains play a crucial role in resisting the deformation of materials, which consequently are responsible for the observed high shear and tensile strengths. Atomic configurations reveal that fracture prefers to occur at the interface of hemicellulose-lignin. DFT calculations of adsorption energy and electron density distribution further demonstrate the strong interaction between cellulose-hemicellulose.

8:50 AM  
Polymer Interfaces with Small-scale Biological Systems and the Impact on Sperm Viability: Jeffrey Bates1; Kenneth Aston1; Benjamin Emery1; Ashwin Velraj1; Abhishek Pachauri1; Parker Toews1; Meredith Humphreys1; 1University of Utah
    The use of assisted reproductive technologies has become more widely understood and readily available to couples who struggle with infertility, and the collection of viable sperm samples is critical to the success of fertility treatments. The materials used for sperm collection that result in sperm viability are not well-understood, and many polymer materials that are currently used are spermicidal, specifically because sperm cells undergo activation by external stimuli and have the potential to lose function upon exposure to certain chemical signals. We leverage what is known about the spermicidal properties of polymers and develop materials that eliminate toxic functional groups found in polymer backbone molecules and additives. We have found that some functional groups are toxic to sperm, while others are not harmful. We also characterize the material properties, processing methods, and synthesis to determine the impact of surface contact at the polymer-sperm cell interface on the viability and functionality.

9:10 AM  
Bioinspired Self-strengthening Tape Junctions: Benjamin Skopic1; Hannes Schniepp1; 1William & Mary
    Fibers are a fundamental building block for many natural materials because of their high tensile strength and, when paired with an adhesive matrix, importance in composites and metamaterials. Fibers are traditionally cylindrical; however, a tape morphology offers significant performance enhancements. For example, the recluse spider spins a 50 nm-thin silk fiber with a high aspect ratio that acts as a microscopic sticky tape without any adhesive coating. The spider makes adhesive junctions of this tape supporting loads corresponding to 400 MPa, enhancing its web’s toughness via looped metastructures. Here we investigate the mechanisms enabling these impressive junctions and develop a model describing its failure mechanics. We show that these junctions self-strengthen to absorb impressively high forces under certain geometric conditions, reaching the tensile strength or lap shear strength of the tape itself.

9:30 AM  
Investigation of Multiscale Hierarchical Structure and Micromechanical Properties of Cholla Cactus: Swapnil Morankar1; Amey Luktuke1; Sridhar Niverty1; Hamidreza Torbati-Sarraf1; Yash Mistry2; Clint Penick3; Dhruv Bhate2; Nikhilesh Chawla1; 1Purdue University; 2Arizona State University; 3Kennesaw State University
    Many biological materials have multiscale hierarchical structures which can inspire the development of high-performance lightweight structural materials. Cholla cactus (Cylindropuntia acanthocarpa) is one such example. Cholla cacti have a mesh-like woody skeleton that has likely evolved to reduce weight and provide support for components that store water to allow the cactus to survive in arid conditions. In the present work, a correlative microscopy-based approach involving x-ray microtomography and scanning electron microscopy was used to understand the multiscale structure of Cholla wood. The three-dimensional data generated by x-ray microtomography was further utilized to extract key structural parameters (size and shape of porosity, length and thickness of cell walls, etc.). Nanoindentation and scanning probe microscopy techniques were employed to understand the micromechanical properties of wood cell walls and were correlated to their hierarchical structure. The impact of the unique hierarchical structure on the design of engineering materials will be discussed.