Mini-Review of Self-Healing Mechanism and Formulation Optimization of Polyurea Coating

Abstract

Self-healing polymers are categorized as smart materials that are capable of surface protection and prevention of structural failure. Polyurethane/polyurea, as one of the representative coatings, has also attracted attention for industrial applications. Compared with polyurethane, polyurea coating, with a similar formation process, provides higher tensile strength and requires shorter curing time. In this paper, extrinsic and intrinsic mechanisms are reviewed to address the efficiency of the self-healing process. Moreover, formulation optimization and strategic improvement to ensure self-healing within a shorter period of time with acceptable recovery of mechanical strength are also discussed. The choice and ratio of diisocyanates, as well as the choice of chain extender, are believed to have a crucial effect on the acceleration of the self-healing process and enhance self-healing efficiency during the preparation of polyurea coatings.

Extrinsic Conditions for the Occurrence and Characterizations of Self-Healing Polyurea Coatings for Improved Medical Device Reliability: A Mini Review

“…30,31 In Singapore, the monthly average maximum temperature of seawater ranges from 28.2 to 31.0 °C, with an average salinity of approximately 35 ppt. 32 Referring to Figure 12, these values suggest that the average potential amount of dissolved oxygen available is about 6 mg −1 , which is sufficient for the polymerization of tung oil. The process of photosynthesis by vegetation can directly influence the concentration of dissolved oxygen.…”

“…However, it is important to consider that the addition of microcapsules may impact the adhesion strength of the coatings to the substrate. Studies conducted by J. Luo et al, Y. Li et al, and M. Samadzadeh et al have demonstrated that a higher concentration of embedded microcapsules can result in a decrease in the adhesion strength of the coatings. − Despite this, the microencapsulation of drying oil has shown excellent self-healing ability and corrosion resistance . Therefore, careful consideration of the microcapsule concentration is necessary to achieve optimal results without compromising the adhesion strength of the coatings.…”

Advanced biopolymer‐based edible coating technologies for food preservation and packaging

“…(a) Extrinsic self‐healing mechanism using microencapsulated healing agents that are released after microcracking has occurred. Source : Reproduced with permission from Luo et al., Polymers, published by MDPI, 2022. (b) Intrinsic self‐healing mechanism utilizing natural cross‐linking bonds that can reconstruct broken bonds resulting from microcracking.…”

Effect of Aromatic Chain Extenders on Polyurea and Polyurethane Coatings Designed for Defense Applications

“…PU-based materials described in the literature are mainly obtained from commercial formulations: prepolymeric diamine components (oligomeric polyether diamines—e.g., Jeffamine ® [ 14 , 21 , 22 ] and Versalink ® [ 23 , 24 ]) and prepolymeric isocyanate components (aromatic isocyanates based on polymeric methylene diphenyl diisocyanate—e.g., Desmodur ® [ 25 ], Rubinate ® [ 26 ], or isophorone diisocyanate [ 27 , 28 ]). Commercial bicomponent prepolymeric formulations (macrodiol and polyisocyanate) are reported for PU-based materials (e.g., Vulkollan ® [ 20 , 29 ] and Multrathan ® [ 20 ]).…”