Research On Supramolecular Self-assembly And Properties Of Functionalized Polysiloxane

Supramolecular polymers, which can be defined as arrays of small molecules held together by noncovalent interactions, offer potential advantages over covalent polymers. Polysiloxane possesses many specific properties, such as low glass transition temperature, hydrophobicity, lubricity, high flexibility of main chains, high gas permeability, low surface tension, chemical and biological inertness and excellent thermal stability due to its unique structure. The supramolecular systems with different structures, morphologies and applications have been constructed by self-assembly, using polysiloxane as structure units. Nowdays, it has been much active frontier research in the fields of polymer chemistry and physics, materials science, bionics and so on. Lanthanide ions have long-lived excited state and efficient strong narrow-width emission bands in the visible region. The properties of the luminescent composite materials, which can be improved by covalently grafting the lanthanide complexes to the polysiloxane backbone have attracted great attention. Additionally, supramolecular polymers based on hydrogen bonding have also been current research hotspots.In this thesis,αωo-hydride terminated polysiloxane (HP) has been synthesized in cationic ring-opening polymerization with materials of octamethylcycoltetrasiloxane (D4) and tetramethyldisiloxane (MHMH). Then diethylmalonate terminated polysiloxane (EP) and malonamide terminated polysiloxane (MP) have been obtained successively by hydrosilylation and ammonolysis, respectively. The FT-IR spectra,1H NMR,13C NMR were used to characterize the structures of HP, EP and MP.Diethyl allylmalonate with similar structure toβ-diketonate was chosen as the functional group of polysiloxane becauseβ-diketonate ligands sensitize Eu3+ and Tb3+ emission. The complexes incorporating EP with the Eu3+ or Tb3+ ions have narrow-width red or green luminescence. Moreover, when integrating heterometallic Eu3+/Tb3+ ions into EP, the luminescence spectra of the complexes were composed of green and red emission. Color-tunable luminescent materials were obtained by tuning the proportions of Eu3+ and Tb3+ ions. MP can form supramolecular polymer based on the hydrogen bonding between the terminal maloanmide groups. In the solid state, MP was characterized by temperature-variable FT-IR, differential scanning calorimetry (DSC), polarizing microscope (POM) and so on. The results showed that MP has temperature responsive properties and conventional smectic A texture was observed at 130℃. Transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to characterize the assemble morphologies of MP in solution, as well as the effects of concentration and polarity of solutions on self-assembly. The results revealed that MP could assemble into spherical micelles at the concentration of 25 mg/10 mL in ethanol solution, it assembled into flat ribbons. However, MP could self-assemble into hollow vesicle in CHCl3/CH3OH (9:1) solution.