Fabrication And Functionalization Of Polymer Multilayer Micro/Nano Structure

Polymer micro/nano structure and its functionalization is multidisciplinary research field of chemistry,material science and nanotechnology.An interdisciplinary approach investigated by synthetic chemists,micromachining materials scientists,physicist and biologists helps to develop new polymers micro/nano structure.The fabrication of polymer micro/nano structure will move towards the more complicated chemical composition and morphological control.Currently,the fabrication methods of polymer-patterned surfaces include ink-jet printing,photolithography,nanoimprinting techniques and BCP lithography and so on.But the fabrication of complex three dimensional(3D)structures with spatial distribution of chemical functionalities remains a challenge.In this paper,we combine colloidal lithography and polymer multilayer structure,successfully achieve the fabrication of 3D periodic polymer multilayer micro/nano structure and the functionalization.In the second chapter,polyelectrolyte layer-by-layer(LBL)films with different morphologies of nanorods,nanowells and stripes were obtained by colloidal lithography and photolithography,and the self-healing capability of LbL films was researched.The crack size can be effectively controlled by above methods,the scratches on the films can be repaired by immersing the films in water or spraying water on them.The self-healing behavior of these crackled films originates from the ability of bPEI and PAA to flow and recombine through electrostatic interaction in the presence of water.We explore the self-healing ability by repeating the damage/healing process and increasing the damage degree.The LbL film could realize damage/healing process for multiple times on the same sample and on the same position of the same sample,after each damage event,the Lb L film completely recovers its original topography.But with the increasing of damage number,the LbL film could not be healed into a smooth film.In addition,with the increase of damage degree of LbL film,polyelectrolyte loss was also increased,the remaining polyelectrolytes were not enough to repair the grooves and the ability of self-healing was correspondingly limited.When the films were damaged for a large degree,thefilms could not be repaired any more.In the third chapter,we demonstrate a facile method combining colloidal lithography,selective ion-exchange,and the in situ reduction of Ag ions for the fabrication of multi-segmented Ag nanoparticle/polymer composite barcode nanorods.The polymer multilayer films were prepared by spin-coating alternating thin films of polystyrene(PS)and polyacrylic acid(PAA),and then multi-segmented polymer nanorods were fabricated via reactive ion etching with colloidal masks.Ag nanoparticles(Ag NPs)were incorporated into the PAA segments by an ion exchange and the in situ reduction of the Ag+.The Ag NP/polymer composite nanorods can be released from the substrate to form suspensions for further coding applications.By increasing the number of segments and changing the length of each segment in the nanorods,the coding capacity of nanorods can be improved.In addition,the sequence of the PAA layers is switchable.More importantly,this method can easily realize the density tuning of Ag NPs in different segments of a single nanorod by varying the composition of the PAA segments.Considering their simple and low-cost fabrication,these encoding nanorods have a wide range of potential applications in product tracking and multiplexed biodetection.Furthermore,we believe that numerous coded materials can be obtained by introducing other functional nanoparticles into the structure of the nanorods.In the fourth chapter,we have fabricated noble metal nanorings and nanoring arrays by a novel and simple method based on colloidal lithography and polymer-assisted self-assembly of nanoparticles.Multisegment polymer nanorod arrays were first fabricated by colloidal lithography.Then they were used as templates for Au NPs adsorption,the assembly process was driven strictly by electrostatic interactions between the positively charged pyridinium groups on the polymer nanorods and the negatively charged ligands of the nanoparticles.Then the fabrication of two,three coaxial Au NPs rings on a polymer nanorod could also be realized by increasing the number of layers of P4 VP and PS.Followed by electroless deposition of gold,continuous gold nanorings were formed.This method allows large area production of gold nanorings or nanoring array structures with precise control over the parameters of nanorings.The nanoring arrays exhibited a strong tunable near-infrared plasmonic absorption band.There are several contributions for thismethod.First,we can easily tune the height and diameter of the nanorings by altering the thickness of the P4 VP segments and etching time.The distance between adjacent gold nanorings can also be adjusted by changing the thickness of PS space layer.Second,3D coaxial gold nanorings with two,three rings were fabricated for the first time.3D coaxial gold nanorings with different diameters on a polymer nanorod were also fabricated by modifying the etching process.Third,these structures can be released from the substrate to form free-standing and dispersible nanorings and nanoring arrays in high yield.We believe this method opens up the possibility to create a variety of metal nanoring arrays with potential applications in the fabrication of plasmonic antenna,plasmonic semiconductors,and negative index metamaterials.