@phdthesis{chen05d,
  author = {Yin-Chu Chen},
  title = {Light Transport in Polymers for Optical Sensing and Photopolymerization},
  school = {Oregon Health \& Science University},
  year = {2005},
  abstract = {This thesis studied light-polymer interaction in fluorescent-based molecularly imprinted polymer (MIP) sensors and photopolymerized dental composites. Through the optical property characterization of the polymers and the light transport modeling in the polymers, an optical MIP sensor design strategy and an optimal photo-cured system for dental composites may be explored.\\[3mm] A MIP is a biomimetic sensing element that is robust and stable in a harsh environment and cheap to produce when compared to immunoassay methods. This thesis investigated the sensitivity factors of MIP sensors consisting of highly cross-linked polyurethane containing anthracene binding sites. Two types of transducers were designed and examined with respect to their fluorescence collection efficiency. The optical properties of MIPs, the fluorescence quantum yield of anthracene in MIPs, and the fluorescence anisotropy property of anthracene and polyurethane were studied. Polyurethane would be an effective waveguide but the high background absorption in the spectrometric regions of interest was a serious problem for sensor sensitivity. The MIP rebinding capacity measured by bath batch was about one micromole/g and was six times more than that of non-imprinted polymers. The fluorescence anisotropy study suggests that anthracene rebinds with MIPs tightly and closely. The detection limit of the MIP sensor was about 15\,ppm of anthracene, which is about 0.1\,$\mu$M/g.\\[3mm] Photocured composites are commonly used as dental restoratives. Due to the large variety of composite formulations and curing-unit types, it is difficult to test the light curing efficiency of all possible combinations. This thesis sought to provide guidelines for optimization of a photopolymerized system based on the light transport model. The quantum yield of photoinitiator conversion and the composite's dynamic optical properties (as curing) were measured.\\[3mm] The photoinitiator conversion (as well as the composite's optical properties, or the composite extent of cure) as a function of radiant exposure was found to fit an exponential model and obey a reciprocity rule for irradiance and illumination time. A dynamic Monte Carlo model to predict the radiant exposure distribution in a medium with dynamic optical properties was constructed and validated. This model will improve understanding of how composite formulations and the spectrum and power of curing units affect curing efficiency.},
}