Facile preparation of patterned petal-like PLA surfaces with tunable water micro-droplet adhesion properties based on stereo-complex co-crystallization from non-solvent induced phase separation processes

Abstract

A facile method to prepare rose petal-like quasi-superhydrophobic poly(lactide) (PLA) membrane surfaces with tunable water droplet adhesion properties based on the stereo-complex co-crystallization of PLAs via non-solvent induced phase separation processes is reported. The co-crystallization of the D- and L-enantiomer of PLA on the bottom surfaces contacting the base glass has led to the formation of hierarchical microstructures containing half-developed to well-developed micrometer-scale papilla or spheres and nanometer-scale folds depending on the thickness of the primary membranes. The bottom surfaces of thinner PLA membranes with primary thicknesses of 100–200 micrometers containing half-developed smaller microspheres and a wider gap space could firmly pin water droplets even upside down with an extremely high adhesion force of about 118–132 μN with water drop breakup, while the bottom surfaces of thicker PLA membranes with a primary thickness of 300–500 micrometers containing larger well developed microspheres with narrower gap space could allow the rolling of water droplets with lower adhesion forces of 74–99 μN. Strategies were developed to create patterned PLA quasi-superhydrophobic membrane surfaces with zoned water droplet adhesion properties for controllable micro-droplet transportation and potentially image encrypting applications.