Describe the research, experiments, and protocols you used in your iGEM project.
Describe the research, experiments, and protocols you used in your iGEM project. These should be detailed enough for another team to repeat your experiments.
If you made Parts this year, please remember to put all information, characterization, and measurement data on the Part's Main Page on the Registry.
ZnO nanoparticles have deodorizing and antibacterial properties. Moreover, the ZnO addition to the polymer matrix can achieve high wear resistance, mechanical stiffness, strength, thermal stability.
Reinforcement effect: ZnO nanoparticles have a high surface area-to-volume ratio due to their nanoscale dimensions. When dispersed within the polymer matrix, these nanoparticles form a strong interface with the polymer chains. During mechanical loading, stress is effectively transferred from the polymer matrix to the ZnO nanoparticles. The nanoparticles then distribute the stress throughout the material, preventing crack propagation and improving the overall strength of the polymer.
Particle-polymer interaction/adhesion: ZnO nanoparticles have polar surfaces that can interact with the polymer chains through van der Waals forces and hydrogen bonding. This interaction enhances the interfacial adhesion between the nanoparticles and the polymer matrix, leading to a more effective load transfer and increased mechanical strength. Furthermore, by restricting polymer chain movement, ZnO nanoparticles act as physical barriers within the polymer matrix, hindering the movement of polymer chains. This restriction of chain mobility contributes to the enhanced mechanical properties, such as increased strength and hardness.
Dislocation pinning: ZnO nanoparticles can act as pinning points for dislocations (structural defects in the crystal lattice) within the polymer matrix. This impedes dislocation movement during deformation and makes the material more resistant to plastic deformation, resulting in improved strength.
Low thermal conductivity of nanoparticles: ZnO nanoparticles have a lower thermal conductivity compared to the polymer matrix. Moreover, ZnO’s increased surface area results in a higher number of interfaces between the nanoparticles and the polymer matrix. At these interfaces, there is scattering of heat due to differences in thermal properties between the nanoparticle and polymer phases. This scattering effect contributes to the reduction of heat transfer through the material.When dispersed within the polymer, these nanoparticles create thermal barriers that obstruct the transfer of heat through the material. As a result, the heat flow is impeded, and the overall thermal conductivity of the polymer nanocomposite is reduced.
Thermal insulation through nanoparticle agglomeration: During the fabrication process of polymer nanocomposites, ZnO nanoparticles may tend to agglomerate or form clusters. These agglomerated structures create thermal barriers within the material, as heat must traverse through the air gaps between the clusters, leading to a decrease in thermal conductivity.
Reflection and absorption of heat: ZnO nanoparticles have unique optical and electronic properties. They can absorb and reflect a portion of incident thermal radiation. This absorption and reflection of heat energy reduce the amount of heat that is transmitted through the polymer nanocomposite, contributing to its enhanced thermal barrier capabilities.
Reduced crystallinity and phonon scattering: The introduction of ZnO nanoparticles can influence the crystallinity of the polymer matrix. Crystalline structures typically have higher thermal conductivities than amorphous regions. The presence of nanoparticles can disrupt the regular packing of polymer chains, leading to increased amorphous regions. Moreover, the phonons (quantized lattice vibrations responsible for heat conduction) in the polymer matrix can scatter at the nanoparticle-polymer interfaces, further hindering the heat transfer process.
UV protection: TiO2 nanoparticles are known for their excellent UV-blocking properties. When added to polymers, they act as UV absorbers, effectively shielding the material from harmful ultraviolet radiation. This makes TiO2-enhanced polymers suitable for outdoor applications, where protection against UV-induced degradation is essential, such as in construction materials and outdoor coatings.
Improved optical properties: TiO2 nanoparticles can modify the optical properties of polymers. They have high refractive index values, which means they can enhance the opacity and whiteness of the polymer, making it suitable for applications like white paints, coatings, and plastics.
Antimicrobial properties: TiO2 nanoparticles possess photocatalytic properties, meaning they can generate reactive oxygen species (ROS) when exposed to UV light. These ROS can have antimicrobial effects, making TiO2-enhanced polymers useful for applications where bacterial or fungal resistance is required, such as in medical devices and food packaging. The photocatalytic properties can be explained due to TiO2’s high bandgap energy, which means it requires higher-energy photons (typically in the UV range) to promote electrons from the valence band to the conduction band. This bandgap energy is around 3.0-3.2 eV for rutile TiO2. Visible light has lower energy, so it does not have enough energy to excite electrons across the bandgap, making TiO2 primarily active under UV irradiation.
Similar to ZnO, TiO2 enhance’s mechanical properties of the polymer, including tensile strength (helpful in flexible polymers).
Electrical properties: TiO2 nanoparticles can improve the electrical properties of polymers. When added to conductive polymers or used in combination with other conductive fillers, they can enhance electrical conductivity and have applications in electronics and sensors. This is likely due to a high dielectric constant due to its structure.
CuO is particularly useful for particular properties such as antimicrobial, UV dissipation, electricity/thermal conductivity. However, these properties simply add on to the properties already enhanced by TiO2 and ZnO. Some properties unique to CuO include:
Flame retardancy: CuO nanoparticles can contribute to the flame retardancy of polymers. They act as char-forming agents during combustion, creating a protective layer that hinders the spread of flames. This makes CuO nanoparticles valuable in fire-resistant coatings and materials.
Gas sensing: CuO nanoparticles have excellent gas sensing properties, particularly for reducing gases. When integrated into polymers, they can create gas-sensitive nanocomposites suitable for gas sensing applications.
Catalysis: CuO nanoparticles can act as catalysts for various chemical reactions. When incorporated into polymers, they can facilitate specific reactions, opening up possibilities for applications in catalysis and green chemistry.
Likewise, some properties unique to SiO2 include:
Reduced coefficient of thermal expansion: SiO2 nanoparticles can help reduce the coefficient of thermal expansion of polymers. This is advantageous in applications where dimensional stability over a range of temperatures is crucial.
Improved gas barrier properties: SiO2 nanoparticles can reduce gas permeability in polymers, making them effective gas barrier materials. This is essential in applications such as food packaging, where preventing gas exchange with the environment is important for preserving the quality and freshness of the contents.
Electrical insulation: SiO2 nanoparticles have excellent electrical insulating properties. When integrated into polymers, they can improve the material's electrical insulation, making it suitable for electrical and electronic applications.
Antioxidant properties: CeO2 nanoparticles exhibit excellent antioxidant behavior. They can scavenge free radicals and reactive oxygen species (ROS), which can prevent oxidative degradation of the polymer matrix. This antioxidant effect contributes to extending the lifespan and durability of the polymer material.
| Properties | ZnO | TiO2 | CuO | SiO2 | CeO2 |
|---|---|---|---|---|---|
| UV Protection | + | + | |||
| Antimicrobial | + | - | + | + | |
| Electrical Conductivity | - | - | + | ||
| Thermal Conductivity | - | + | + | ||
| Gas Barrier | + | - | + | ||
| Scratch/Wear Resistance | - | - | + | ||
| Flame Retardancy | - | + | |||
| Mechanical Strength | + | + | + | ||
| Thermal Stability | - | + | + | ||
| Biocompatibility | - | + | + | + | |
| Gas Sensing | - | - | + | ||
| Catalyst | - | - | |||
| Antioxidant | - | + | + |
+ means increases this property
- means decreases this property
**Blank cells indicate that there is no significant effect or relevant data available for that particular combination of nanoparticle and property.