Construction Of The Dynamic Wrinkle Micropattern On Polymer Surface

Patterned surfaces are of fundamental importance to materials,physics,chemistry and biology science,bearing significant applications both in natural and man-made events such as biological functions,interface engineering,micro-nano manufacturing and so on.The ability to tune reversible pattern morphology that can possibly enable the on-demand dynamically control of the surface properties has attracted a great deal of attention because of the wide range of potential applications of such morphologies in enhanced and tunable optical devices,responsive microfluidic channels,flexible electronic devices,switchable wettability,smart adhesion,and biomaterials.Despite the great promise of the surface patterns,they still encounter some challenges.At one hand,plenty of various materials and key components were consumed and multistep and/or complicated fabrication processes are usually involved during the generation of dynamic pattern.At the other hand,more important than the burdensome preparation procedures,it is still a challenge to produce the dynamic surface patterns since the morphologies of instability patterns are prepensely defined or fixed by the fabrication systems.In this thesis,we presented a novel strategy for patterned surfaces with dynamic wrinkle based on dynamic chemistry.The dynamic wrinkled surface can enable the on-demand control of surface properties,and provide an important alternative to realize a smart surface,promising for a wide range of potential applications in the enhanced and tunable optical devices,responsive microfluidic channels,switchable wettability surfaces,smart adhesion and friction properties.The concept of smart patterned surface based on dynamic wrinkle are fundamental and versatile,and it is expected there to be extensive future work based on it in generalizing the work to other smart materials and systems,and in using the dynamic pattern systems to tune not just morphology but functional properties encoded in the system’s topography.In the first part,we present a facile and effective strategy for the fabrication of a reversible wrinkle pattern with a morphology that can be dynamically erased and tuned in situ by simply controlling the dynamic Diels-Alder(D-A)chemical reaction between furan and maleimide.The key point for this strategy is that the modulus of the top layer can be tuned by the reversible dynamic D-A reaction cross-linking.The reversible nature of the D-A click chemistry enables the dynamic change of the pattern morphology from the smooth state to the wrinkle pattern,allowing for accurate control of the adhesion,wettability and optical properties of the resulting surface.The generation and elimination of wrinkles are the consequence of the dynamic evolution of the compressive stress field regulated by the modulus mismatch between the bilayers through the dynamical D-A reaction.This one-step and robust approach for the fabrication of complex tunable wrinkle patterns provides the possibility that surface properties can be controlled on demand.Such highly reversible wrinkle patterns can enable wide applications for the surfaces of functional intelligent materials with topographies and properties that can be in-situ tuned on-demand in a dynamically chemical way,especially in the cases where the discrete,ex-situ physical stimuli are limited or even alter the intrinsic properties of the material.The second part presented a novel library of multi-scale complex patterns where hierarchical wrinkles can be dynamically generated and eliminated by insitu photo-control.Atom Force Microscope(AFM)results and UV-vis kinetics manifests that the change of surface modulus induced by dynamic photodimerization of anthracene-containing polymer P(An-BA)coated top-layer plays a crucial role in triggering the morphology switch of the resulting wrinkled surface with the self-healing,tunable adhesion and wettability properties.Based on the temporal and spatial characteristics of dynamic photo-dimerization,the ordered and hierarchical patterns can be obtained through adapting selective exposure and photolithography.Furthermore,a series of hierarchical patterns in which the smaller-scale wrinkles can be prescriptive generated on the assigned micro-pillar arrays,making up sets of Braille characters,were demonstrated for Braille text refreshable typography through photo-reversible formation and erasure.This novel and effective approach for photoreversible hierarchical wrinkle pattern offers great promise for smart devices and surface for dynamical tunable morphology and surface properties on demand in response to light stimuli without altering the bulk properties.At the third part,we present a facile and bottom-up strategy to fabricate a selforganized micro-/nanosacle patterned surface whose morphology can be changed timely and spatially by light.The complex pattern was fabricated on the surface of a photo-curing coating through a one-step,self-patterned process,in which selfassembly of fluorinated azobenzene(AZO)-containing polymer and photoreversible isomerization lead to the generation of compressive stress,resulting in the formation of a reversible surface pattern.The reversible change of the pattern morphology allows for light control of the adhesion and wettability of the surface.Moreover,the one-step approach to fabricate the complex pattern possesses characteristics similar to the formation process of the self-organizing micro/nano patterns in nature.The feasibility and generality of this approach for obtaining such bio-inspired,photo-reversible,and self-organized patterned surfaces will find wide applications in functional intelligent materials with properties that can be tuned on-demand without altering the material’s intrinsic properties.The fourth part focused on a novel and effective strategy for obtaining a near infrared(NIR)light reversible hierarchical pattern,wherein nanostructure arrays pattern was fabricated atop dynamic micro-wrinkle platform.Unique characteristics of NIR light such as the rapid responsibility,high reversibility,onoff controllable,non-invasive operability,convenience and light orthogonality make this approach promising for practical applications.Besides the tunable optical transmittance properties,the Au-coated hierarchical patterns combining micro/nano-scale pattern arrays and larger-scale micro-wrinkle exhibit high potential for the surface enhanced Raman substrate.Also,the Au-coated hierarchical patterned PDMS can be served as a soft sensor for dynamically detecting the plasma effect.This novel and robust strategy for the NIR-reversible hierarchical pattern inherently possesses unique advantages of the rapid response,controllable operability and accurate region-selectivity,thus paves the way to align and locate smart materials in desired topography and surface properties for smart surface and devices by dynamically tuning surface geometry in acute response to light stimuli without altering the bulk properties.At the end,we concluded by summarizing our work and offering our perspective on future developments of this rapidly evolving field.