Selective [2 + 2]-Cycloaddition in Methacrylic Stilbene Polymers without Interference from E/Z-Isomerization
摘要:
Stilbene is known to undergo two different reactions upon photochemical excitation. The first is an E/Z isomerization and the second is a [2 + 2]-cycloaddition of two stilbene molecules. Because both reactions occur in parallel their use is limited. Here we report on photorefractive polymers with a methacrylate backbone and covalently attached 4-hydroxy-(E)-stilbene or 3,5-dimethoxy-4-hydroxy-(E)-stilbene units in the side chain which show [2 + 2]-cycloaddition only. Both polymers, poly(4-methacryloyloxy-(E)-stilbene) (PMAES) and poly(4-methacryloyloxy-3,5-dimethoxy-(E)-stilbene) (PMADMES), show very high initial refractive indices of 1.6533 for PMAES and 1.6288 for PMADMES. The photochemical reaction upon laser irradiation with 355 nm was monitored by UV/vis, fluorescence, and IR spectroscopy. The light-induced changes of the refractive index at 633 nm measured by surface plasmon resonance (SPR) were found to be Delta n > 0.05 for PMAES and Delta n > 0.04 for PMADMES. The sensitivity of PMADMES is enhanced compared to PMAES due to the electron donating groups (EDG) as the direct comparison of both polymers shows. Both polymers are useful for optical devices because they do not show any absorption in the visible range and are noncrystalline as determined by wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC).
External additive for toner for electrophotography, toner for electrophotography, double-component developer for electrophotography, image forming process using the toner, and image-forming apparatus using the toner
申请人:Ricoh Company Ltd.
公开号:EP1383010A1
公开(公告)日:2004-01-21
An external additive for a toner for electrophotography which contains oxide fine particles which contain silicon, in which the oxide fine particles have a primary particle diameter of 30nm to 300nm in number average, a standard deviation σ of a particle size distribution of the primary particle diameter satisfies a relation of: R/4 ≤ σ ≤ R, in which the R expresses the primary particle diameter,
the oxide fine particles are substantially spherical having a circularity SF1 defined as equation (1) of 100 to 130 and a circularity SF2 defined as equation (2) of 100 to 125;SF1 = (L2/A) ×(π/4) × 100SF2 = (P2/A) × (1/4π) × 100 in the equations, "L" expresses the absolute maximum length of the oxide fine particles; "A" expresses a projected area of the oxide fine particles; and "P" expresses a maximum perimeter of the oxide fine particles.
External additive for toner for electrophotography, toner for electrophotography, double-component developer for electrophotography, image-forming process using the toner, and image-forming apparatus using the toner
申请人:——
公开号:US20040067189A1
公开(公告)日:2004-04-08
An external additive for a toner for electrophotography which contains oxide fine particles which contain silicon, in which the oxide fine particles have a primary particle diameter of 30 nm to 300 nm in number average, a standard deviation &sgr; of a particle size distribution of the primary particle diameter satisfies a relation of: R/4≦&sgr;≦R in which the R expresses the primary particle diameter,
the oxide fine particles are substantially spherical having a circularity SF1 defined as equation (1) of 100 to 130 and a circularity SF2 defined as equation (2) of 100 to 125;
SF
1=(
L
2
/A
)×(&pgr;/4)×100 equation (1)
SF
2=(
P
2
/A
)×(¼&pgr;)×100 equation (2),
in the equations, “L” expresses the absolute maximum length of the oxide fine particles; “A” expresses a projected area of the oxide fine particles; and “P” expresses a maximum perimeter of the oxide fine particles.
US7611815B2
申请人:——
公开号:US7611815B2
公开(公告)日:2009-11-03
Selective [2 + 2]-Cycloaddition in Methacrylic Stilbene Polymers without Interference from <i>E</i>/<i>Z</i>-Isomerization
作者:Martin Schraub、Helen Gray、Norbert Hampp
DOI:10.1021/ma2015485
日期:2011.11.22
Stilbene is known to undergo two different reactions upon photochemical excitation. The first is an E/Z isomerization and the second is a [2 + 2]-cycloaddition of two stilbene molecules. Because both reactions occur in parallel their use is limited. Here we report on photorefractive polymers with a methacrylate backbone and covalently attached 4-hydroxy-(E)-stilbene or 3,5-dimethoxy-4-hydroxy-(E)-stilbene units in the side chain which show [2 + 2]-cycloaddition only. Both polymers, poly(4-methacryloyloxy-(E)-stilbene) (PMAES) and poly(4-methacryloyloxy-3,5-dimethoxy-(E)-stilbene) (PMADMES), show very high initial refractive indices of 1.6533 for PMAES and 1.6288 for PMADMES. The photochemical reaction upon laser irradiation with 355 nm was monitored by UV/vis, fluorescence, and IR spectroscopy. The light-induced changes of the refractive index at 633 nm measured by surface plasmon resonance (SPR) were found to be Delta n > 0.05 for PMAES and Delta n > 0.04 for PMADMES. The sensitivity of PMADMES is enhanced compared to PMAES due to the electron donating groups (EDG) as the direct comparison of both polymers shows. Both polymers are useful for optical devices because they do not show any absorption in the visible range and are noncrystalline as determined by wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC).