Studies On Meta-linked Water-soluble Poly(Phenyleneethynylene):Synthesis, Optical Properties And Applications In Sensor

Water-soluble conjugated polymers (WSCPs) are widely used as highly sensitive fluorescent sensory materials for a variety of chemical analytes and biomolecules due to their unique optical and electrical properties as well as water-soluble characteristics. In recent years, chemical and biological sensors based on WSCPs have become a research hotspot and focus.WSCPs exhibit various aggregation with the alteration of structure and environmental conditions due to their amphiphilic nature. This is one of the most important factors which influence their photophysical property and results of fluorescence detection. In the thesis, we prepared a series of meta-linked cationic water-soluble poly(phenyleneethynylene)(m-PPE-NEt2Me+) first, we study the structure-property relationship through modifying the aggregation of WSCPs by means of structure design and changing environmental conditions.The contents are as follows:1. A series of m-PPE-NEt2Me+with different side chains P1’-P3’ were synthesized. Through Sonogashira reaction and post-quarternization treatment, three polymers were obtained and their quaternization degrees were almost100%. They can be dissolved in a polar organic solvent(such as DMSO and methanol),but a little in water.2. Their solvent-and pH-influenced self-assembly behavior and conformation changes were studied by means of analyzing the changes of PL spectra and dynamic light scattering data. In good solvent methanol P1’ adopted random-coil conformation while it folded into helix conformation in water. P2’and P3’didn’t exhibited the similar self-assembly behavior but they produced apparent aggregation.Pl’exhibited the tendency of folding into helix conformation with the pH increase in these two solvents mixture at the volume composition of MeOH/H2O (4/1). P2’and P3’didn’t exhibited the similar self-assembly behavior maybe because of the side chain effects.Finally the possible application of the WSCPs on chemical and biological sensing has been carried on the preliminary exploration.3. Through the introduction of benzothiazole unit into m-PPE-NEt2Me+backbone, the meta-linked cationic water-soluble polymers P4’were designed and synthesized. Its solvent-and pH-influenced self-assembly behavior and conformation changes were studied by means of analyzing the changes of PL spectra and dynamic light scattering data. In good solvent methanol they adopted random-coil conformation while they folded into helix conformation in water. But it didn’t exhibited the similar self-assembly behavior by increasing of pH.