Adhesion failure of antiscratch coatings on polycarbonate under UV irradiation

Abstract

The adhesion failure of antiscratch (AS) coatings on unmodified and plasma-modified polycarbonate (PC) substrate was studied using both chemical and physical methods while considering the surface and interface changes between coatings and PC under ultraviolet (UV) irradiation. The differences in the wettability and surface elemental compositions of the PC surface (PCs) and AS coatings after UV ageing were evaluated by contact angle and Fourier transform infrared (FTIR) measurements. The nanoindentation technique was employed for the quantitative assessment of the changes in the nanomechanical properties of both PCs and AS coatings under UV irradiation. The adhesion of coating on plasma-modified PC was found to be significantly better than that of unmodified substrates. The hydrophilicity and polarity of PCs covered by AS coatings were significantly increased because of the photodegradation of PCs, whereas silicon coatings remained invariant. Nanoindentation tests revealed an obvious enhancement in stiffness of the coating and exposed PC after ageing. Based on these experiments, we proposed that adhesion failure under UV irradiation may be caused by two reasons: first, the photodegradation that occurred at the PCs covered by AS coatings; and second, the stress induced by the changes in stiffness of both AS and PCs under UV ageing.

Ultrastable and Durable Silicone Coating on Polycarbonate Surface Realized by Nanoscale Interfacial Engineering

“…The properties of PC/S, UVC-PC/S, and Nano-PC/S samples were compared comprehensively to investigate the advantages of coating on the nanostructured surface over conventional coating on a flat surface and activated surface (UVC treated surface) (Figure a). The cross-sectional images are shown in Figure b; it was found that the PC/S sample displayed an obvious interfacial gap due to the modulus and surface energy mismatch between PC and silicone . The interfacial gap is significantly mitigated on the UVC-treated PC surface because of the enhanced surface energy of PC (c.f.…”

“…On the contrary, Nano-PC/S still maintained a smooth surface. The cracking of coatings was mainly caused by the stress generated during UV irradiation due to the UV-induced mismatching of mechanical properties of the coating material and substrate material . The concentration of stress in long-time UV exposure will lead to cracking or detachment of the coating layer.…”

“…The interfacial adhesion between the coating layer and the substrate is one of the greatest challenges due to the difference in modulus, surface energy, and the lack of tough bonding between the two materials. ,, The delamination of the coating in a harsh environment, during long-term service, or under repetitive deformation severely deteriorates the functionality of the coating and its life span. , Therefore, improving the interfacial adhesion via a practical approach is a grand challenge and has considerable potential economic value. So far, various surface pretreatment techniques have been extensively studied to increase the interfacial adhesion of coatings, such as plasma treatment, − wet chemical treatment, − UV irradiation, − and laser treatment. − These methods mostly focused on increasing the surface energy of substrate polymers by introducing polar functional groups such as hydroxyl groups and carboxyl groups, thereby improving the chemical bonding between coatings and substrate.…”

Plasma pretreatment of polycarbonate substrates for indium zinc oxide film deposition

“…The cleaned PC plates were modified under the Ar/oxygen plasma generated by a gridless ion beam source with low energy. Additional details about this process can be found in our work . Prior to pretreatment, the reactor was vacuumed to a base pressure below 3 × 10 −3 Pa.…”

Adhesion and thermal stability enhancement of IZO films by adding a primer layer on polycarbonate substrate

“…Commercially available 1 mm thick PC sheets (GE9030, General Electric co., USA) were rinsed with neutral detergent, ethanol, and distilled water, then dried at 70 °C for 1 h before surface pretreatment. The silicone coating material was prepared using sol–gel methods . An initial solution was prepared by mixing acid‐silica, methyltriethoxysilane (MTES), and tetrothoxysilane (TEOS) using HCOOH as catalyst.…”