The Modification Of Microstructured Polymer Optical Fiber And Its Applied Fundamental Studies

Microstructured Polymer Optical Fiber （MPOF）, a special kind of fiber with airholes running parallel to its axis and for all its length, has attracted increasing interestsfor their characters: moderate price, chemical stability, promising optical property andbiocompatibility. Subsequently, some works were carried out based on MPOF in manyfields. In this thesis, new methods for modifying MPOF, application of basic researchfor modified MPOF in the fields of chemical sensing and photocatalytic degradation oforganic solute were studied.The development history of MOF, the current status of developments of MOF, thecurrent status of developments and research of optical fiber chemical sensor, and thedevelopment of TiO₂photocatalytic reactor are briefly introduced in the first chapter.Based on this introduction, this thesis’ characteristics and significance are proposed.In the second chapter, the fabrication methods of MOF preform was introduced andcompared. Taking account of the problems exist in these methods in general, we chooseexcuding-moulding method invited by our group. This method is not time-consumingand suitable for manufacture on a large scale. It also made the incorporate excuding ofMPOF preform realized.18holes,36holes and547holes MPOF performs were madeby the method. Subsequently, MPOF performs were drawed by the mode of subareaheating.18holes and36holes MPOF were made for application of basic research in thefield of chemical sensing.547holes MPOF secondary performs were made forapplication of basic research in the field of photocatalytic degradation of organic solute.In the third chapter, a novel MPOF chemical probe fabricated by directly inhalingcellulose acetate （CA）-acetic acid mixed solution doped with Rhodamine6G （R6G）into array holes in a MPOF and then forms R6G-CA film in them. The fluorescentcharacteristics of the probe were investigated with the change of concentration of nitritein sulfuric acid solution with a certain concentration. The calibration graph offluorescence intensity versus nitrites concentration was linear in the concentration range.It has been applied to the determination of nitrites in real samples with satisfactory results.In the fourth chapter, the side wall of the MPOF was firstly treated with acidcatalyzed hydrolysis of PMMA surfaces and then fluorescence indictor eosin wasloaded on the surface of the inner wall of the MPOF by covalent bond. Therefore, a pHprobe was made based on the modified MPOF. The calibration graph of fluorescenceintensity versus hydrogen peroxide concentration is linear in a concentration range of2.0-4.4. The reproducibility of the probe is good without evidently dye leaking.In the fifth chapter, the sol-gel technique was combined with the holey structure ofMPOF. A highly sensitive MPOF probe for hydrogen peroxide was made by formingrhodamine6G-doped titanium dioxide film on the side wall of array holes in a36holeMPOF. Since The refractive index of TiO₂gel thin film is reported about1.9, which ismuch higher than that of PMMA （1.49） and aqueous solution （about1.33）, theR6G-TiO₂-MPOF probe could be seen as a thin-film optical waveguide array, based onthe theory of thin-film optical waveguide. It was found that hydrogen peroxide onlyhave a response to the MPOF probe in a certain concentration of potassium iodide insulfuric acid solution. The calibration graph of fluorescence intensity versus hydrogenperoxide concentration is linear in a concentration range. It was used to thedetermination of H₂O₂in a few of real samples with satisfactory results.In the sixth chapter, a novel photocatalytic reactor having547pieces ofTiO₂-nanofilm-modified capillaries, which is derived from a MPOF preform is designed,constructed and tested. TiO₂-film-modified MPOF preform is obtained by directlyinhaling P25-doped TiO₂sol into array holes of MPOF and forming TiO₂film on theirside walls. The MPOF perform play not only a role as a light-transmitting media, also aTiO₂supporting and waste-water pipe to supply for photocatalytic degradation of toxicorganic solute. Methylene blue （MB） was chosen as the model contaminants in water.The effects of loading quantity of TiO₂, pH of MB and initial concentration of MB wereinvestigated. The photocatalytic reactor has so large surface area for TiO₂loading thatphotodegradation efficiency was enhanced. As far as we know, the photocatalytic reactor based on the super multichannel capillary waveguide arrays has not beenreported before.In the seventh chapter, the monolith photocatalytic reactor is designed, constructedand tested with one model compounds （Rhodamine B） for overall performanceevaluation. The photocatalytic active TiO₂nanocrystal film is obtained by microwaveprocessing of the TiO₂gel films in the MPOF. It was demonstrated that thephotocatalysis efficiency enhancement can be achieved with small doses of hydrogenperoxide. The effect of initial dye concentrations and H₂O₂concentration wereinvestigated.In the end, a conclusion was made about the work during the studies of Ph.D.candidate.