Dual-responsive shape memory polymer arrays with smart and precise multiple-wetting controllability

Abstract

Smart-controlled surface wettability from superhydrophilicity to superhydrophobicity has been extensively explored, and stimulus-responsive strategies have been widely accepted as a useful method to realize reversibility. However, achieving smart and precise wetting control remains challenging because most previous studies focused on stimulating single surface chemistry or microstructures. Herein, a dual-stimulus-responsive strategy that can synergistically stimulate surface chemistry and microstructures is demonstrated on the pH-responsive molecule poly(2-(diisopropylamino)ethyl methacrylate (PDPAEMA)-modified temperature-triggered shape memory polymer (SMP) arrays. The responsive PDPAEMA and SMP can provide the surface with tunable surface chemistry and microstructures, respectively. Thus, the wetting of the surface between various states can be reversibly and precisely controlled from superhydrophilicity to superhydrophobicity with contact angle (CA) differences of less than 15° under the cooperative effect between the adjustable surface microstructure and chemistry. The surface is further utilized as a platform to create gradient wettings based on its excellent controllability. Therefore, this work presents a strategy for surface wetting control by combining tunable surface microstructures and chemistry. The prepared samples with a special wetting controllability can be applied to numerous fields, including adaptive liquid microlenses, accurate drug release, and selective catalysis. This work also proposes novel expectations in designing smart functional surfaces.