Bioinspired Molecular Composites of 2D-Layered Materials and Tandem Repeat Proteins
Restricted (Penn State Only)
- Author:
- Colak, Oguzhan
- Graduate Program:
- Engineering Science and Mechanics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- August 23, 2024
- Committee Members:
- Laura Cabrera, Program Head/Chair
Melik Demirel, Chair & Dissertation Advisor
Vincent Meunier, Major Field Member
Sahin Ozdemir, Major Field Member
Adri van Duin, Outside Unit & Field Member - Keywords:
- 2D Materials
Tandem Repeat Proteins
Molecular Dynamics
Mechanical Properties
Interface Dynamics - Abstract:
- Composites with well-ordered and precisely designed molecular structures have the potential to showcase extraordinary physical properties. A high degree of order in the composite’s molecular structure can lead to remarkable properties, such as high strength, stiffness, and toughness. Nacre is a natural example of how hierarchical structure optimization influences mechanical properties. At the smallest scale, nacre is composed of calcium carbonate (aragonite) and an organic matrix (mainly proteins and polysaccharides). The aragonite platelets are arranged in a brick-and-mortar pattern, where the platelets act as bricks, and the organic matrix serves as mortar. This structure provides a combination of stiffness and toughness, allowing nacre to absorb energy and resist fracture. These layers are stacked on top of each other, forming a composite material that is much tougher and more resilient than either the mineral or organic components alone. Inspired by this natural example, we utilized a hierarchical approach to fabricate new composite materials where 2D nanosheets, specifically graphene oxide (GO) and titanium carbide (MXene), act as fillers, and squid ring teeth (SRT)-inspired tandem repeat (TR) proteins serve as the matrix. Similar to a brick-and-mortar structure, the proteins act as the mortar, distributing the load to the stiffer 2D nanosheets stacked on top of each other. To better understand the driving parameters of these novel materials, we employed molecular dynamics simulations. We modeled the 2D nanosheets of graphene oxide fillers combined with recombinant squid-inspired tandem repeat proteins and simulated these composites to match the existing experimental data. Our results showed that TR proteins enable precise molecular length and structure control, resulting in consistent mechanical properties that align with experimental studies. These findings confirmed the experimental results and provided deeper insights into the molecular mechanisms behind their enhanced mechanical properties. The mechanical properties of the composite scale linearly based on the number of repeat units in the tandem proteins. This innovation pushes the boundaries of materials engineering and opens a future where we can engineer the physical properties of composites to achieve desired levels of mechanical strength and flexibility