Transforming waste to treasure: Superhydrophobic coatings from recycled polypropylene for high-value application

Polypropylene is a widely used general-purpose plastics with significant production, resulting a large amount of waste. While physical recycling of single-component waste polypropylene is a viable option, its performance deteriorates after several recycling cycles, limiting its reuse at value added products. This study employs solid-state shearing milling technology to achieve ultrafine-pulverization of waste polypropylene at ambient temperature to produce micro-scale polypropylene powder. The micro-nano surface structure is created synergistically using polypropylene powder and nano-silica, with hydrophobic polydimethylsiloxane as a binder, leading to the development of superhydrophobic coating. The superhydrophobic coating exhibits outstanding self-cleaning abilities, superior resistance to acid, alkali, and salt, and a water contact angle of 159°. This paper presents a novel approach to producing a high value-added superhydrophobic coating from deterioration waste polypropylene, which has potential application in building waterproofing, anti-freezing, self-cleaning coatings and moisture collection, addressing environmental concerns related to plastic waste and promoting the circular economy.