Surface Plasmon Coupled Emission For Polymer Films

Surface plasmon coupled emission(SPCE)technique,based on the near-field interaction between fluorophores and surface plasmons on metal surfaces,has attracted increasing attention in sensor technology,bioanalysis,and cell imaging as it displays unique optical properties like strongly directional emission,unique polarization,wavelength resolution,thickness dependence and background suppression.Polymer brushes are layers of polymer chains grafted to an interface,which generally is a solid substrate.The architectures of the surface-attached polymer chains show responsive behavior to external stimuli,such as pH value,temperature,solvent,light and salt concentration,etc.The combination of polymer brushes with SPCE will have numerous application in sensing.The optical properties of SPCE with Kretschmann(KR)excitation,particularly in thick dielectric layers,have not been extensively studied to the best of our knowledge.After thoroughly investigating the properties of SPCE with KR excitation,we used SPCE technique to continuously monitor the electrochemically mediated atom-transfer radical polymerization(eATRP)behavior and stimuli-response of polyacrylamide brushes.This dissertation consists of five chapters.Chapter 1 serves as an introduction,providing an overview of surface plasmon resonance(SPR),plasmon waveguide resonance(PWR)and SPCE,including principles,significant optical properties as well as applications of SPCE;and an introduction to polymer brushes including polymerization strategies,architecture,substrate,characterization techniques and applications.Chapter 2 provides an introduction to a scanning angle fluospectro-electrochemistry instrument with multiple operating modes.The fluospectro-electrochemistry instrument can be used to simultaneously investigate the optical and electrochemical properties at an interface and to observe eATRP in situ.Because of simple construction,convenient operation and low cost,the fluospectro-electrochemistry instrument can be expected to become rapidly useful in a variety of analytical and sensing applications.Chapter 3 describes both the excitation and the emission properties of SPCE from Rhodamine B in PMMA films over a large thickness range up to 2000 nm in the KR configuration on gold substrate.The experimental results show that either the incident angle(s)or the emission angle(s)and polarization of SPCE are strongly dependent on the thickness of the PMMA film.The SPR-mode fluorescence was generated in thin PMMA films with a thickness less than about 80 nm,and the PWR-mode fluorescence was generated in PMMA films with a thickness more than 60 nm.The SPCE fluorescence intensity is also dependent on the thickness of the PMMA film.Based on SPCE theory,more optical sensors will be designed and applied in many areas.Chapter 4 describes the development of three SPCE methods,including SPCE fluorescence measurements,scanning angle SPCE and SPCE Imaging,for the in situ observation of eATRP behavior of polyacrylamide brushes in the KR configuration.Then the thickness of dry polymer brushes was measured using scanning angle SPCE,and the stimuli response behavior of polymer brushes was studied using SPCE fluorescence measurements in situ.Controllable polymerization of polymer will give a decisive impetus to the development of polymer based SPCE sensor.Chapter 5 considers the innovative aspects and the development of SPCE.