Mini-Review of Self-Healing Mechanism and Formulation Optimization of Polyurea Coating
Abstract
:1. Introduction
2. Self-Healing Mechanisms of Polyurea
2.1. Extrinsic Mechanisms
2.1.1. Microcapsule Self-Healing
2.1.2. Vascular Network Self-Healing
2.2. Intrinsic Mechanisms
2.2.1. Physical Interaction
2.2.2. Chemical Interaction
- (a)
- Supramolecular
- (b)
- Dynamic Covalent
2.3. Comparison between Extrinsic and Intrinsic Mechanisms
3. Factors Affecting Self-Healing Efficiency
3.1. Chain Mobility
3.1.1. Factors Affecting Chain Mobility
- (a)
- Molecular Weight
- (b)
- Presence of Pendant Group
- (c)
- Glass Transition Temperature
3.1.2. Influence of Choices on Chain Mobility
3.2. Microphase Separation
3.3. Time before Surfaces Are in Contact
3.4. Equilibrium Kinetics
4. Novel Strategy of Preparation of Self-Healing Polyurea
4.1. Choice of Isocyanate
4.2. Ratio of Different Isocyanates
4.3. Choice of Chain Extender
5. Conclusions and Position
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Stages | Definition |
---|---|
1. Surface rearrangement | The roughness or topography of the surface changes with external factors (pressure, time, and temperature). |
2. Surface approach | Healing can only occur when surfaces are brought together, or a gap is filled with healing fluid. |
3. Wetting | Surfaces have to wet each other and form an interface before healing can occur. |
4. Diffusion | The most critical stage of strength development. |
5. Randomization | Refers to the equilibration of the non-equilibrium conformations of chains near the surfaces. |
Advantages | Disadvantages | |
---|---|---|
Microcapsules (Extrinsic) |
|
|
Vascular network (Extrinsic) |
|
|
Dynamic bonds (Intrinsic) |
|
|
Stages | Importance | Factors | |
---|---|---|---|
Physical interaction (Intrinsic): 5-Stage crack healing | 1. Surface rearrangement | Emphasizes the importance of Tg and relaxation time of surface molecules | Chain mobility |
2. Surface approach | Emphasizes the need for separated pieces to be in contact | Time before the surfaces are in contact | |
3. Wetting | Rate determining with surface rearrangement | Chain mobility | |
4. Diffusion | Affected by number of chains and number of monomers diffused | Chain mobility | |
5. Randomization | Restoration of the molecular weight distribution and random orientation of chain segments | Equilibrium kinetics (chain extender used) | |
Chemical interaction (Intrinsic): Dynamic bonds | Bonds capable of undergoing repetitive breaking and reformation | Equilibrium kinetics (chain extender used) |
Name | Abbreviation | Mw (g/mol) | Chemical Structure |
---|---|---|---|
4,4′-Diphenylmethanediisocyanate | MDI | 250.25 | |
Toulene-2,4-diisocyanate | TDI | 174.2 | |
1,4-Butanediisocyanate | BDI | 142.16 | |
Chemical Name | Structure | Abbreviation of Polyurea Formed | ||
---|---|---|---|---|
2,2,6,6-Tetramethylpiperidine | | TMPCA | 88 | - |
tert-Butyl-ethylamine | | TBEU | 0.21 | |
Diethylamine | | DEU | 0.0011 |
Diisocyanate | Abbreviation | Chemical Structure |
---|---|---|
Isophorone diisocyanate | IPDI | |
Hexamethylene diisocyanate | HDI72 | |
4,4-Dicyclohexylmethane diisocyanate | HMDI | |
Chemical Name | Abbreviation | Chemical Structure |
---|---|---|
Bis(4-aminophenyl) disulfide | AFD | |
4,4′-Diaminodibenzyl | MDA | |
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Luo, J.; Wang, T.; Sim, C.; Li, Y. Mini-Review of Self-Healing Mechanism and Formulation Optimization of Polyurea Coating. Polymers 2022, 14, 2808. https://doi.org/10.3390/polym14142808
Luo J, Wang T, Sim C, Li Y. Mini-Review of Self-Healing Mechanism and Formulation Optimization of Polyurea Coating. Polymers. 2022; 14(14):2808. https://doi.org/10.3390/polym14142808
Chicago/Turabian StyleLuo, Junzhi, Tao Wang, Celine Sim, and Yuanzhe Li. 2022. "Mini-Review of Self-Healing Mechanism and Formulation Optimization of Polyurea Coating" Polymers 14, no. 14: 2808. https://doi.org/10.3390/polym14142808
APA StyleLuo, J., Wang, T., Sim, C., & Li, Y. (2022). Mini-Review of Self-Healing Mechanism and Formulation Optimization of Polyurea Coating. Polymers, 14(14), 2808. https://doi.org/10.3390/polym14142808