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1	Anchoring behavior of chiral liquid crystal at polymer surface in polymer dispersed chiral liquid crystal films Wu, Haixia. January 2004 (has links) (PDF) Thesis (M.S.)--Textile and Fiber Engineering, Georgia Institute of Technology, 2004. / Griffin, Anselm, Committee Member; Srinivasarao, Mohan, Committee Chair; Park, Jung O., Committee Member. Includes bibliographical references (leaves 101-105).
2	Coherent soft x-ray dynamic light scattering from smectic-A liquid crystals / Price, Allen C., January 1999 (has links) Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves [179]-184). Liquid crystal films. Grenz rays. Light
3	Anchoring Behavior of Chiral Liquid Crystal at Polymer Surface: In Polymer Dispersed Chiral Liquid Crystal Films Wu, Haixia 13 April 2004 (has links) Chiral Liquid Crystals (CLCs) can selectively reflect light of a specific wavelength when the period of its helically twisted structure is appropriately chosen and white light propagates along the helical axis. This phenomenon makes CLCs attractive for reflective-color display, without the needs of backlighting, polarizers, or color filters. Polymer Dispersed Chiral Liquid Crystals (PDCLC) have been developed for reflective switchable, bistable color display. However they suffer from high external driving voltage, low reflectivity, and high cost in pretreatment of the substrates. The key to solve these problems is to understand and control the anchoring behavior of CLC at a polymer surface. This research has two purposes: to develop PDCLC films with high reflectivity and to investigate the factors affecting the anchoring behavior of CLC at the polymer surface of the film. Specifically, commercially available chiral dopant and nematic liquid crystals were carefully chosen to formulate the CLCs reflecting different color. These CLCs are mixed with various acrylate and methacrylate monomers respectively, and UV cured at varied conditions to obtain PDCLC films. The anchoring behavior of these films is characterized using polarized optical microscopy, confocal microscopy, and microscopic-spectrophotometer. The factors influencing the anchoring behavior include chemical structure of the monomers, effective diameter of individual cells in PDCLC, thickness of individual cells in PDCLC, and the pitch of CLC, among which the chemical structure of the monomers is the most important. The PDCLC film made with n-hexyl methacrylate is found to selectively reflect light with the reflectivity larger than that of pure CLC with the same pitch. Liquid crystal films Polymer liquid crystals Reflectance Reflectance Liquid crystal films Polymer liquid crystals
4	Coupled self-assembly and flow alignment of silver nanorods Murali, Shanthi, Davis, Virginia A., January 2008 (has links) (PDF) Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 86-99).
5	Characterization of heterogeneous diffusion in confined soft matter Täuber, Daniela 26 October 2011 (has links) (PDF) A new method, probability distribution of diffusivities (time scaled square displacements between succeeding video frames), was developed to analyze single molecule tracking (SMT) experiments. This method was then applied to SMT experiments on ultrathin liquid tetrakis(2-ethylhexoxy)silane (TEHOS) films on Si wafer with 100 nm thermally grown oxide, and on thin semectic liquid crystal films. Spatial maps of diffusivities from SMT experiments on 220 nm thick semectic liquid crystal films reveal structure related dynamics. The SMT experiments on ultrathin TEHOS films were complemented by fluorescence correlation spectroscopy (FCS). The observed strongly heterogeneous single molecule dynamics within those films can be explained by a three-layer model consisting of (i) dye molecules adsorbed to the substrate, (ii) slowly diffusing molecules in the laterally heterogeneous near-surface region of 1 - 2 molecular diameters, and (iii) freely diffusing dye molecules in the upper region of the film. FCS and SMT experiments reveal a strong influence of substrate heterogeneity on SM dynamics. Thereby chemisorption to substrate surface silanols plays an important role. Vertical mean first passage times (mfpt) in those films are below 1 µs. This appears as fast component in FCS autocorrelation curves, which further contain a contribution from lateral diffusion and from adsorption events. Therefore, the FCS curves are approximated by a tri-component function, which contains an exponential term related to the mfpt, the correlation function for translational diffusion and a stretched exponential term for the broad distribution of adsorption events. Lateral diffusion coefficients obtained by FCS on 10 nm thick TEHOS films, thereby, are effective diffusion coefficients from dye transients in the focal area. They strongly depend on the substrate heterogeneity. Variation of the frame times for the acquisition of SMT experiments in steps of 20 ms from 20 ms to 200 ms revealed a strong dependence of the corresponding probability distributions of diffusivities on time, in particular in the range between 20 ms and 100 ms. This points to average dwell times of the dye molecules in at least one type of the heterogeneous regions (e.g. on and above silanol clusters) in the range of few tens of milliseconds. Furthermore, time series of SM spectra from Nile Red in 25 nm thick poly-n-alkyl-methacrylate (PnAMA) films were studied. In analogy to translational diffusion, spectral diffusion (shifts in energetic positions of SM spectra) can be studied by probability distributions of spectral diffusivities, i.e. time scaled square energetic displacements. Simulations were run and analyzed to study contributions from noise and fitting uncertainty to spectral diffusion. Furthermore the effect of spectral jumps during acquisition of a SM spectrum was investigated. Probability distributions of spectral diffusivites of Nile Red probing vitreous PnAMA films reveal a two-level system. In contrast, such probability distributions obtained from Nile Red within a 25 nm thick poly-n-butylmethacrylate film around glass transition and in the melt state, display larger spectral jumps. Moreover, for longer alkyl side chains a solvent shift to higher energies is observed, which supports the idea of nanophase separation within those polymers. heterogene Diffusion fest-flüssig Grenzfläche Lagenbildung Einzelmoleküldetektion Fluoreszenzmikroskopie Fluoreszenzkorrelationsspektroskopie Einzelmolekülverfolgung Simulation weiche Materie TEHOS smektisch-A 8CB Poly-n-alkylmethacrelat ultradünne Flüssigkeitsfilme dünne Flüssigkristallfilme dünne Polymerfilme Oberflächensilanole thermisches SiO2 spektrale Diffusion heterogeneous diffusion solid-liquid interface liquid layering single molecule detection fluorescence microscopy fluorescence correlation spectroscopy single molecule tracking simulation soft matter TEHOS smectic-A 8CB poly-n-alkyl methacrylate ultrathin liquid films thin liquid crystal films thin polymer films surface silanols thermally grown SiO2 spectral diffusion ddc:530 ddc:541 Weiche Materie Fluoreszenzmikroskopie Thermotroper Flüssigkristall Flüssigkristall-Farbstoff-System Flüssigkeitsfilm Polymerfilm Anisotrope Diffusion Anomale Diffusion Diffusion Optisches Spektrum Nanostrukturiertes Material Simulation
6	Characterization of heterogeneous diffusion in confined soft matter Täuber, Daniela 20 October 2011 (has links) A new method, probability distribution of diffusivities (time scaled square displacements between succeeding video frames), was developed to analyze single molecule tracking (SMT) experiments. This method was then applied to SMT experiments on ultrathin liquid tetrakis(2-ethylhexoxy)silane (TEHOS) films on Si wafer with 100 nm thermally grown oxide, and on thin semectic liquid crystal films. Spatial maps of diffusivities from SMT experiments on 220 nm thick semectic liquid crystal films reveal structure related dynamics. The SMT experiments on ultrathin TEHOS films were complemented by fluorescence correlation spectroscopy (FCS). The observed strongly heterogeneous single molecule dynamics within those films can be explained by a three-layer model consisting of (i) dye molecules adsorbed to the substrate, (ii) slowly diffusing molecules in the laterally heterogeneous near-surface region of 1 - 2 molecular diameters, and (iii) freely diffusing dye molecules in the upper region of the film. FCS and SMT experiments reveal a strong influence of substrate heterogeneity on SM dynamics. Thereby chemisorption to substrate surface silanols plays an important role. Vertical mean first passage times (mfpt) in those films are below 1 µs. This appears as fast component in FCS autocorrelation curves, which further contain a contribution from lateral diffusion and from adsorption events. Therefore, the FCS curves are approximated by a tri-component function, which contains an exponential term related to the mfpt, the correlation function for translational diffusion and a stretched exponential term for the broad distribution of adsorption events. Lateral diffusion coefficients obtained by FCS on 10 nm thick TEHOS films, thereby, are effective diffusion coefficients from dye transients in the focal area. They strongly depend on the substrate heterogeneity. Variation of the frame times for the acquisition of SMT experiments in steps of 20 ms from 20 ms to 200 ms revealed a strong dependence of the corresponding probability distributions of diffusivities on time, in particular in the range between 20 ms and 100 ms. This points to average dwell times of the dye molecules in at least one type of the heterogeneous regions (e.g. on and above silanol clusters) in the range of few tens of milliseconds. Furthermore, time series of SM spectra from Nile Red in 25 nm thick poly-n-alkyl-methacrylate (PnAMA) films were studied. In analogy to translational diffusion, spectral diffusion (shifts in energetic positions of SM spectra) can be studied by probability distributions of spectral diffusivities, i.e. time scaled square energetic displacements. Simulations were run and analyzed to study contributions from noise and fitting uncertainty to spectral diffusion. Furthermore the effect of spectral jumps during acquisition of a SM spectrum was investigated. Probability distributions of spectral diffusivites of Nile Red probing vitreous PnAMA films reveal a two-level system. In contrast, such probability distributions obtained from Nile Red within a 25 nm thick poly-n-butylmethacrylate film around glass transition and in the melt state, display larger spectral jumps. Moreover, for longer alkyl side chains a solvent shift to higher energies is observed, which supports the idea of nanophase separation within those polymers. info:eu-repo/classification/ddc/530 ddc:530 info:eu-repo/classification/ddc/541 ddc:541

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