Magnetic-directed fillers migration during micro-injection molding of magnetic polypropylene nanocomposite surfaces with uplifted light trapping microarchitectures for freezing delay and photothermal-enhanced de-icing

Abstract

Micro-roughness and low-surface-energy anti-icing surfaces attract tremendous interest from researchers due to superhydrophobicity and low ice affinity. However, the rapid fabrication of superhydrophobic surfaces (SHS) without developed microstructure via template methods has been the bottleneck for further applications. In this work, ferroferric oxide (Fe3O4) loaded with graphene (GP) as magnetic nanoparticles are introduced into the polypropylene (PP) matrix as a heat vehicle for superhydrophobic anti-icing/de-icing surfaces. Microarchitectured PP/GP/Fe3O4 surfaces are fabricated via a combining method of micro-injection molding and magnetic attraction. An analysis of directed particles migration with magnetic attraction is conducted using a multi-physical field coupling model. The magnetic attraction boosts micropillars with a height from ∼85 to ∼150 μm and keeps surfaces maintaining water contact angles at a high level (∼153°) and the stable air plastron for repetitive droplet impacting at an initial velocity of 1 m s−1. With full-grown micropillars, light can be absorbed more efficiently by elongating the optical path for multiple reflections to occur. In comparison with neat PP surface, the light-to-heat performance of the composite surface shows an increase in temperature from ambient to 94 °C within 67 s under one sun irradiation at an intensity of 1 kW m−2 and a decrease in ice adhesion strength from ∼30 to ∼9 kPa within the same period. The photothermal efficacy of the magnetic particles confers a prolonged delay in icing on SHS. A practical application of manufacturing of SHS is expected to be possible due to their excellent passive anti-icing and active de-icing properties for outdoor injection parts.