The Regular Annealing Pattern Of Polymer Blend Flims:Mechanism And Applications

In this thesis,the annealing structure of Polystyrene(PS)/Poly(methyl methacrylate)(PMMA)blend film is investigated,utilized these structures as mask,optical resonators can be fabricated,and its application in surface enhanced Raman scattering is studied.Four parts are mainly included as following:(1)The characteristic length scale during annealing of PS/PMMA blend film with weight ratio 1:1.Our experiment shows that the evolution of PS/PMMA blend film with weight ratio 1:1 during annealing is a spinodal process,in which exists a characteristic length scale.And the characteristic length scale increases during annealing as PS-rich phases merge,and approaches to a stable value gradually.This stable characteristic length scale is related to initial thickness of PS/PMMA blend film,and increases as the blend film gets thicker.(2)The fabrication of optical resonators utilizing the annealing structure of the PS/PMMA blend film as templates and its application in surface enhanced Raman spectroscopy(SERS).The basic process for fabricating optical resonators is constituted of annealing of polymer blend film,reactive ion etching(RIE)and metal evaporation.Such a resonator presents enhanced transmission with tunable resonant position.In order to reveal the underlying physics of the experimentally measured transmission spectra,electromagnetic simulation is performed with commercial software(Rsoft,Fullwave)based on finite-difference-time-domain(FDTD)method,which agrees the experimental data.The size of resonator can be tuned by adjusting the thickness of PS/PMMA blend film,so does the resonant frequency.The application of the resonators in SERS is also studied.(3)Confinement-Induced Ordering Effect in Dewetting and Phase Separation of Polymer Blend Film.We demonstrate a unique process for the formation of ordered pattern in dewetting and phase separation of polymer blend film on a periodically excavated silicon substrate.Once a lateral geometrical confinement is applied to the polymer blend film,the film may evolve to a perfectly ordered array of droplets when proper initial film thickness and interstitial separation of the holes on the substrate are selected.We suggest that our observation provides an example where interaction among the building blocks(the polymer droplets)and the interaction between the building block and the physical boundary of geometrical confinement work together to organize an ordered pattern.(4)Dewetting via Nucleation on Physically Patterned SubstratesTake PS thin film on SiOx as an example,we studied dewetting via nucleation of holes on physically patterned substrates.After annealing PS droplets form in the center of interstice between micro holes.The micro holes can be considered as initial nuclei,and these nuclei grows during annealing.