Producing of high-transparent antiscratch nanohybrid thin films on polycarbonate substrate

Abstract

In the present work, a new aqueous sol–gel procedure has been used for producing hard transparent organic–inorganic nanohybrid coatings on polycarbonate (PC) substrate for improving its optical and mechanical properties. Sol-gel thins films were prepared by mixing Si and Al aqueous precursors and applied them on the cold plasma treated PC substrate. TEOS, GPTMS and aluminum tri sec-butoxide were used as main precursors. In order to improve the adhesion strength onto polymer, PC substrates were treated by Dielectric Barrier Discharge (DBD) system being conducted at atmosphere pressure in open air. The effects of sol ratios, curing temperature and aging time on the prepared coatings properties were investigated. Chemical, structural, morphological, optical and mechanical characteristics of the samples were studied by ATR-FTIR, EDS, XRD, FE-SEM, TEM, UV/vis spectroscopy, pencil hardness and eraser scratch methods. The obtained results indicated that the water contact angle of PC (73.24°) decreased to 6.32° by 45 second plasma treatment due to added functional groups on the treated surfaces. All of the films showed higher optical transmittance (89%) than the raw PC (86%) that was stemmed from the lower refractive index of the prepared films. Films indicated good adhesion onto the plasma treated substrates (5B). The pencil hardness of the PC substrate (4B) improved to 3H (8 pencil grade increment) with just a single layer coating (about 200 nm thickness) due to the preparation of new hard structures of interlocked Si and Al atoms.

A Comprehensive Outlook of Scope within Exterior Automotive Plastic Substrates and Its Coatings

“…However, the reflector consists of complex structures involving specific plastics and a highly efficient process. In regard to increasing the scratch resistance and hardness, four methods are usually included [55,56]. Such methods include sol-gel and/or hard coatings, coatings applied by either physical or chemical vapor deposition (PVD/CVD), the incorporation of hard nano materials into melted polymer, and finally, plasma-enhanced chemical vapor deposition.…”

“…The incorporation of nano fillers has also been reported to be beneficial in increasing the interfacial area and required transparency in clear coats [59,60]. Several research studies conducted recently attest to this system, along with the capability of a high degree of dispersion of in situ nanoparticles [56]. The metal alkoxide precursor method undergoes condensation and hydrolysis reactions to form a 3D inorganic network wherein hard nanoparticles increase the flexibility, adhesion, and fracture toughness.…”

“…However, one of the key challenges has been the high vacuum and expensive equipment required for the much-needed plasma treatment of PC substrates for surface energy increase. To that extent, dielectric plasma discharge has been reported wherein binary sol-gel thin films were coated, resulting in a lower refractive index coating as compared to silica hybrid coatings [56].…”

“…In that context, sputtering is regarded as a more environmentally friendly method than electrolytic coatings. Conventionally, the chrome plating process was very popular with its protective properties combined with a (a) Illustration of three-layer concept of a hard coating for PC consisting of epoxy primer layer, aminosiloxanes as bridging layer, and an acrylic UV-cured anti-scratch layer [68,72], (b) modeling and simulation technique for better sideview mirror coating application [73], and (c) different sol-gelbased PC coatings showing better anti-glare, anti-scratch, and anti-fog properties with good cross-cut adhesion [56,58].…”