Confinement, composition, and spin-coating effects on the glass transition and stress relaxation of thin films of polystyrene and styrene-containing random copolymers: Sensing by intrinsic fluorescence

Pure organic luminogens with fluorescence–room temperature phosphorescence (RTP) dual emission have significant fundamental importance and promising applications. So far, most dual emissive materia...

Aggregation-Induced Dual Emission and Unusual Luminescence beyond Excimer Emission of Poly(ethylene terephthalate)

Syndiotactic polystyrene (sPS) films with uniplanar-axial orientation of their co-crystalline phase with a fluorescent guest (naphthalene, NP) have been prepared and the orientation of their crystalline phase has been fully characterized by X-ray diffraction measurements. The prepared films have been examined in detail using Nishijima's method, where angular distribution of NP polarized fluorescence intensities was measured at each setting film angle by the rotation of films around the excitation light beam. This polarized fluorescence method turns out to be quite effective for monitoring the orientation of fluorescent guest molecules in the films. In particular, in semicrystalline films presenting uniplanar-axial orientation of their sPS/NP clathrate phase, NP molecules were found to exhibit a high three-dimensional orientational order all over the films. The experimental data have also allowed to determine the orientation of the NP guest molecule with respect the axes of the co-crystal unit-cell: in satisfactory agreement with molecular modeling results, angles formed by the short and the long axes of NP with the c axis are not far from 80° while the angle between the short axis of NP and the a axis is nearly 105°.

Guest Orientation in Uniplanar-Axial Polymer Host Films and in Co-Crystal Unit-Cell, Determined by Angular Distributions of Polarized Guest Fluorescence.

Mass spectrometry investigation of the degradation of polyethylene terephtalate induced by low-energy (<100 eV) electrons

Cyclotriveratrylene (CTV) has attracted much attention because of its good chemical stability, small cavity, stable conformation, and facile modification. In this article, two water-soluble CTV derivatives (CTV-G and CTV-L) functionalized by glucose and lactose residues were synthesized, respectively. Unexpectedly, sugar-bearing CTVs exhibit a distinct photoluminescence, which might be ascribed to the enhanced planar conformation of cyclotriveratrylene ring derived from the spatial effect of bulky branch groups. The interaction between the water-soluble CTV derivatives and C(60) was investigated in organic solvent and aqueous solution, which was further characterized by fluorescence spectra, ultraviolet-visible spectra, and Raman spectra. CTV-G can associate with C(60) to form supramolecular complex with 1:1 molar ratio (K(a) = 1.38 × 10(5) M(-1), 298 K). As for CTV-L, a similar complex with a lower association constant (K(a) = 5.09 × 10(4) M(-1), 298 K) can also be formed.

Noritaka Kobayashi

Papers

Microenvironments in poly(ethylene terephthalate) film revealed by means of fluorescence measurements