ABSTRACT
We have investigated the molecular orientation of glassy poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) layers formed on photo-aligned polyimide films with different in-plane anisotropy. The polyimide contains azobenzene in the backbone structure (Azo-PI), allowing us to control the in-plane anisotropy of the film by varying linearly polarized light (LP-L) exposure. The glassy PFO layers (approximately 30 nm thick) were obtained by annealing the samples at the liquid crystalline phase of PFO and then quenching them to room temperature. The degree of alignment of PFO was assessed by the polarization ratio of photoluminescence (PL). The PL polarization ratio increased rapidly with the LP-L exposure, and it reached 10 at 2.8 J/cm(2). Beyond this LP-L exposure, it became almost constant around 10.4. This PL polarization ratio was much higher than the absorption dichroic ratio of the underlying Azo-PI film. This result suggests that the degree of alignment of PFO is determined by its liquid crystalline nature. The saturation dependence of the degree of alignment is very useful for fabricating alignment patterns by a simple photo-mask exposure method. We have succeeded in fabricating 3 microm line-and-space alignment patterns of PFO.
Subject(s)
Fluorenes/chemistry , Fluorescence Polarization , Imides/chemistry , Photochemistry/methods , Azo Compounds/chemistry , Fluorenes/classification , Imides/classification , Microscopy, Polarization , Molecular Structure , Polymers/chemistry , Polymers/classification , Solubility , Spectrometry, FluorescenceABSTRACT
Synthesis and derivatization of a series of substituted tetrahydrofluorenone analogs giving potent, ERbeta subtype selective ligands are described. Several analogs possessing ERbeta binding affinities comparable to 17beta-estradiol but with greater than 75-fold selectivity over ERalpha are reported.
Subject(s)
Estrogen Receptor beta/drug effects , Fluorenes/chemical synthesis , Fluorenes/pharmacology , Cell Line , Crystallography, X-Ray , Estrogen Receptor alpha/chemistry , Estrogen Receptor alpha/drug effects , Estrogen Receptor beta/chemistry , Fluorenes/classification , Humans , Ligands , Models, Molecular , Molecular Structure , Stereoisomerism , Structure-Activity RelationshipABSTRACT
In this paper we present a near-field microscopy study of thin films of a phase-separated blend of the fluorescent conjugated-polymer poly(9,9-dioctylfluorene) [PFO] with the non-fluorescent polymer polymethylmethacrylate [PMMA]. A scanning near-field optical microscope (NSOM) was used to generate (blue) fluorescence from the PFO following UV excitation at 362 nm. A range of different concentrations of PFO in PMMA were studied ranging from 1 to 50% PFO in PMMA by mass. By studying both the shear force and fluorescence images we were able accurately to determine the distribution of PFO in the PMMA. We found that phase separation occurs over a number of different length-scales between 5 micro m and 250 nm. We show that at PFO concentrations of 1%, the PFO lies on top of the PMMA. At a PFO relative concentration of 50%, the PMMA phase extends through the whole thickness of the film to the underlying substrate. We use such samples to discuss the resolution of NSOM when imaging thick organic films. Furthermore, we confirm that the length-scales of phase separation can be modified via control over spin-casting protocols.
