Polylactide Films with Superhydrophobicity and Superior Mechanical Properties Constructed by Combining Annealing Stretching and Nonsolvent-Induced Phase Separation

SustainablePLA films with superhydrophobicity and superiormechanical properties are constructed by combining annealing stretchingand NIPS-based surface structuring. Polylactide(PLA) is regarded as one of the most promising substitutesfor petroleum-based thermoplastics, but the inherent nature of hydrophilicityand poor toughness severely limits its widespread application. Inthis work, PLA films with superhydrophobicity and outstanding mechanicalproperties are fabricated by combing "annealing stretching"and nonsolvent-induced phase separation (NIPS)-based surface modification.The prepared films have low surface adhesion characteristics, exhibitingwater contact angles of up to 163.4 degrees and extremely small slidingangles as low as 1 degrees. Excellent self-cleaning function to solidcontaminates and good repellency to several liquid contaminates arealso demonstrated. In addition, the strong interfacial adhesion betweenthe structured surface coating and the substrate enables the PLA filmsto resist various chemical and mechanical damages, exhibiting splendiddurability under severe environmental conditions. Moreover, a superbstiffness-toughness balance is obtained. The tensile strength,Young's modulus, and elongation at break of the fabricatedPLA film are 98.9 MPa, 2.87 GPa, and 91.7%, respectively, which aredramatically improved compared to that of the unstructured castingPLA film (57.6 MPa, 1.57 GPa, and 21.0%, respectively). This workwould provide significant guidance for the facile and potentiallylarge-scale preparation of PLA films with mechanical robustness andsuperhydrophobicity and could broaden their application scope to self-cleaningand moisture-proof fields.