Preparation And Application Of Siloxane Based Fluorescent Porous Materials

Organosilicon porous materials as a novel silicone functional material have been widely applied in gas storage and separation,catalysis and other fields.However,compared with other organic porous materials,organosilicone porous materials are less studied,and most researches mainly focus on the advantages of silicone monomers,the applications mainly focus on the field.of gas storage and separation owing to its porous property.Other functional material need to be explored,especially in fluorescence and other fields.In this dissertation,four aspects of explorations have been carried out and focus on the preparation and application of organosilicon fluorescent porous materials.1.A class of POSS-based fluorescent porous polymers have been.prepared by Heck reactions of octavinylsilsesquioxane(OVS)With brominated aromatic c.ompounds.Two sets of reaction conditions were employed to retrieve their original appearance.These materials exhibit tunable appearance with the colors from dark colors to various colors and the physical.forms from coarse powders with irregular shape particles to fine powders with relatively uniform solid spheres by altering the reaction conditions.This finding is mainly attributable to the fluorescence quenching effect induced by the residuals,i.e.,palladium black,catalyst in the final networks.In addition,these materials show efficient fluorescence quenching for nitrobenzene vapour,thereby indicating their potential application as sensing agents for the detection of explosives.2.Development of rapid,sensitive,and visual detection of nitroaromatic explosives is of great importance for homeland security and human safety.Herein,three novel fluorescent nanoporous polymers were prepared by Heck reactions of octavinylsilsesquioxane with ethene derivatives.HPP-2 dispersion in ethanol exhibited highly sensitive detection of explosives and high selectivity for detecting TNT and PA.To achieve a straightforward visual detection of explosives,we further developed a novel paper sensor based on the filter paper impregnated with the nanoporous fluorescent polymer.This developed paper sensor is promisingly applied for rapid and visual sensing of explosive residuals.The remarkable fluorescence and reusability of this sensor could be expanded to other fluorescence detection of residuals.3.Processability has always been a challenge for most insoluble porous materials.Herein,we report a facile approach to realize their processability by physically blending them into polysiloxane matrix followed by a crosslinker,resulting in novel silicone elastomers.The applied porous materials are polyhedral oligomeric silsesquioxane-based hybrid porous polymers(HPPs),which were prepared by the Heck reactions of octavinylsilsesquioxane with 4,4'-dibrombiphenyl and/or 1,3,6,8-tetrabromopyrene.They exhibit tunable fluorescence with a continuous color change from blue to red by altering the molar ratio of biphenyl and pyrene units.It was observed that HPP materials were well dispersed in the polymeric matrix when the amount of HPPs was below 20 mg/g of PMMS.Furthermore,multicolored ultraviolet light-emitting diodes(UV-LEDs)based on these silicone elastomers were constructed by an in situ cross-linking method.These results reveal that blending insoluble porous materials with a polymer matrix is an effective strategy to realize their processability and results in excellent fluorescent composites.This simple strategy could be certainly expanded to other insoluble porous materials.4.The construction of porous polymers linked by flexible building units have still been considered as a big challenge.Here we report the design and synthesis of three fluorescent porous polymers(FPPs),FPP-1?FPP-3,by Heck reactions of a commercially available 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane with brominated pyrene,tetraphenylethene,and spirobifluorene.The resultant materials exhibit high porosity,strong fluorescence,and tunable emission colors from brick-red to yellow and green.By virtue of the high contrast and sensitivity,and low detection limit of FPPs-adhered fingerprints,they can serve as effective fluorescent probes with strong anti-interference ability for the identification of latent fingerprints in actual conditions(e.g.,rainy environment).Taking FPP-3 as an example,its ethanol suspension exhibits highly sensitive detection of nitroaromatic explosives and metal ions,especially the selective detection of 2,4,6-trinitrotoluene(TNT)orpicric acid(PA),and Fe3+.A further developed paper sensor was found to be sensitive to the solution,solid and vapor phase of explosives and Fe3+ with rapid response time through a visual detection,and thus is suitable for rapid,on-site and visual sensing of explosives and Fe3+ residuals.