Robust poly(2-hydroxyethyl acrylamide) copolymer coatings with excellent antifogging ability, high transparency, superior scratch resistance, and self-cleaning properties

Although polyethylene terephthalate (PET) materials have been widely applied in many fields, such as food packaging containers, fiber textiles, electronic components and medical devices, owing to changes in ambient temperature or humidity, the surface of PET materials is prone to fog during use, which limits their application in the field of high light transmittance requirements. In this study, a new strategy for constructing transparent, water-resistant and scratch-resistant PET antifogging coatings based on P(HEAA- co -THFA- co -ITA) copolymers is proposed. The copolymer is first synthesized via radical copolymerization of 2-hydroxyethyl acrylamide (HEAA), tetrahydrofuran acrylate (THFA) and itaconic acid (ITA) in aqueous solution. Afterward, the copolymer solution was coated on the surface of the PET substrate, and a transparent anti-fog coating formed after thermal curing treatment. In the copolymer coating, the hydrophilic PHEAA chain segment is rich in amide and hydroxyl groups, which endows the material with excellent hydrophilicity and antifogging functions. The hydrophobic component PTHFA not only inhibits the swelling of the coating caused by water absorption but also enhances the adhesion between the coating and the PET material. Moreover, the PITA segment endows the coating with good water resistance stability and scratch resistance through multiple intermolecular hydrogen bonds involving carboxyl-carboxyl, carboxyl-hydroxyl and carboxyl-amide groups. The experimental results show that the prepared transparent coating has excellent antifogging performance in both the hot steam method and the freeze warm test. There was no coating peeling after the quartz sand wear test under dry conditions or after approximately 40 wet cloth wiping experiments under wet conditions, indicating that the coating has good scratch resistance. After boiling in 80°C water for 30 min, the coating maintained 85% light transmittance and outstanding antifogging performance, demonstrating excellent water resistance and thermal stability. Therefore, this copolymer antifogging coating has promising application prospects.