Carbon quantum dots-driven surface morphology transformation towards superhydrophobic poly(lactic acid) film

Focused on the design and implementation of superhydrophobic surface of poly(lactic acid) (PLA) film, the novel morphology regulating strategy (i.e., carbon quantum dots (CQDs)-nucleated interfacial-crystallization induced phase separation) is reported to fabricate CQDs-grafted-poly(D-lactic acid)/poly(L-lactic acid) (CQDs-g-PDLA/PLLA) films with tailorable hierarchical micro-nano structures. The hierarchical structures of CQDs-g-PDLA/PLLA films evolve from laminar protrusions to microspheres to petal-like structures and further to micro-nano sphere structures, only by adjusting the CQDs-g-PDLA content. 30 wt% CQDs-g-PDLA/PLLA film with lotus leaf-like microstructures exhibits a record-high contact angle of 168° and a rather small sliding angle of 7.8°, indicating the pretty superhydrophobicity. Constructing controllable hierarchical structures is key factor to attain the superhydrophobicity, instead of commonly introducing suitable nanoparticles or hydrophobization agents. In combination with the high porosity, 30 wt% CQDs-g-PDLA/PLLA film illustrates a maximal oil-absorption up to 9.7 g/g. This strategy provides a novel insight into designing and constructing superhydrophobic PLA materials for the enormous application potential in surface self-cleaning and oil-water separation.