Self-wrinkling To Fabricate Patterned Surface Of Photo-crosslinking Coating

Wrinkles is all over the Nature,playing an indispensable role in the evolutionary process.As a representation of nature rule,it spans many orders of magnitude at length scales,from Grand Mountain to wings of butterfly.Furthermore,these wrinkles more than sense of beauty,but endow the creatures with specific functions,for example,hydrophobicity,drag-reduction and adhesion control.Therefore,considerable attention has been drawn to fabricate patterned surface and probe the associated properties.For construction methods,by far,can be classified into two categories:top-down and bottom-up.The former,including laser etching,mold printing and photolithography,is limited by complicate process as well as expensive facility;the latter,bionically,comprises of block copolymers(BCP)assembly,layer-by-layer(LBL)assembly and swelling method,is still restricted by multiple procedures and elaborate synthesis.For these reasons,developing a facile,efficient strategy whereby functional coating with patterned wrinkles can be reached still remains a meaningful exploration.In this paper,by taking advantage of self-assembly and photo-curing technology,we propose a self-wrinkling strategy which impart morphological pattern and a series of properties to the obtained coating.Research details and results are listed as follows:(1)We prepared a functional coating with self-wrinkling surface and synergistic assembly of silver nanoparticle by utilizing interfacial self-assembling fluorocarbon chain:Fluorinated Polymeric Photoinitiator(FPPI)can spontaneously migrate into resin/air interface because of low surface energy,meanwhile,the complexed silver precursor with amidogen in the polymer chain is synergistically assembled,resulting in a bilayer structure.Under UV illumination,contractive stress accumulates which is a result of the different shrinkage between layers with more double bonds in the bottom than those in the top.Once the intensity of stress surmounts a critical value,wrinkles happen as a form of stress release.Furthermore,nanoparticles are reduced while tend to wrinkle the surface with a wrinkle-to-ridge transition.We investigated the mechanism as well as different functionalities,such as hydrophobicity,self-replenishing and anti-bacterial property.(2)We presented a non-contact type of photolithography by exploiting photodimerization of anthracene,to transform random wrinkles into ordered pattern with given mask:during UV illumination,photodimerization of anthracene causes thermal expansion and crosslinking.In a system of gradient polymerization,crosslinking in the upper layer proceeds to a great extent than that in the substrate.When cooling down,the mismatch of shrinkage between bilayers leads to increasing stress,which further results in wrinkles after excess the critical point.With Laser Scanning Confocal Microscope,we studied the characteristic wavelength and amplitude of varying thickness,and the ordered patterns by mask;discussed the wrinkling mechanism for random wrinkles and ordered pattern;confirmed the rewritable ability by multiple erasable tests.