含Rhodamine B之白光螢光材料：製備與其應用性質研究

Rhodamine B (RhB)-containing materials with white-light photo- luminescence (PL) were prepared in this work. In the first part, white-light PL silica nanoparticles were synthesized and used as applications of preparation of PL polymer films and nanofibers. RhB physically adsorbs or chemically bonds to silica nanoparticle (SNP) surfaces, resulting in PL SNPs. The RhB-modified SNPs exhibit white-light PL emissions under an excitation at 365 nm, which is different from the inherent yellow light emission of RhB. The SNPs with physically-adsorbed RhB show stimuli-responsive properties. In solutions, the RhB molecules which physically adsorb to SNPs release from SNPs, consequently turning the PL emission from white-light to yellow. On the other hand, the SNPs having covalently-bonded RhB molecules are effective additives for preparation of white-light PL polymer composites. Both PL poly(methyl methacrylate) (PMMA) films (from casting process) and nanofibers (from electrospinning process) showing white-light PL emission have been prepared. In the second part of this work, RhB aggregation into nanoparticles was performed through UV-light illumination. Along with this aggre- gation, the PL behaviors (under excitation at 365 nm) of RhB also changes, from a yellow light (RhB molecules) to a white-light (RhB nanoparticles) emission. The formation of RhB nanoparticles and the changes in the PL emissions are reversible. As a result, a novel approach to generate organic fluorescent nanoparticles and to prepare white- light-emitting fluorescent materials has been demonstrated. The third part is preparation of RhB-anchored amphiphilic poly(poly(ethylene glycol) methacrylate)-b-poly(glycidyl methacrylate) block copolymer (polyPEGMA-b-PGMA/RhB) by a sequential atom transfer radical polymerization (ATRP) and post-functionalization of RhB. The chemical structure of polyPEGMA-b-PGMA/RhB is characterized with gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), and 1H nuclear magnetic resonance spectroscopy (1H-NMR). PolyPEGMA-b-PGMA/RhB has shown self-assembly behaviors in tetrahydrofuran (THF) and aqueous solutions. The RhB aggregation induced with the inter-molecular interaction of RhB result in the various core-shell structures of the assembled nanoparticles. The PL properties of the polyPEGMA-b-PGMA/RhB nanoparticles are structure- dependent and exhibit yellow-light, blue-light, and white-light emissions. The fluorescent organic nanoparticles of polyPEGMA-b-PGMA/RhB were used as a bio-dye for cell labelling. In the last part of this work, polymeric toroid from homopolymer has been demonstrated. Toroids of RhB end-capped poly(N-isopropyl- acrylamide) (polyNIPAAm-RhB and RhB-polyNIPAAm-RhB) have been obtained with a temperature-driven self-assembly process. The RhB molecules at the chain ends of polyNIPAAm provide PL properties to the polymeric toroids of RhB-terminated polyNIPAAm. Otherwise, The RhB moieties of polymer chain end play a critical role in toroidal self- assembly. RhB-terminated polyNIPAAm was also used to prepare supramolecular polymers with β-cyclodextrin (β-CD) dimer. As-prepared polymeric toroids from supramolecular polymers displayed highly uniform shape and size. Nevertheless, this strategy, temperature-driven self-assembly process, opens a new window to developing toroid-shaped polymers.