The study of the orientation of polyvinyl chloride films by means of birefringence and infrared, visible, and ultraviolet dichroism

Shindo, Yohji; Read, B. E.; Stein, Richard S.

doi:10.1002/macp.1968.021180118

Cited by 77 publications

(28 citation statements)

References 45 publications

(10 reference statements)

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“…[26,[28][29][30][31][32] By applying a modified Strickler-Berg approach, different cavity models have been developed, which should be taken into account to estimate the influence of refractive index changes on the fluorescence lifetime. [33] As the solvent is expelled from the volume occupied by the fluorescent molecule, a cavity is created in which the fluorophore is located.…”

Section: à3mentioning

confidence: 99%

Fluorophores as Optical Sensors for Local Forces

et al. 2009

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The main aim of this study is to investigate correlations between the impact of an external mechanical force on the molecular framework of fluorophores and the resultant changes in their fluorescence properties. Taking into account previous theoretical studies, we designed a suitable custom-tailored oligoparaphenylenevinylene derivative (OPV5) with a twisted molecular backbone. Thin foils made of PVC doped with 100 nM OPV were prepared. By applying uniaxial force, the foils were stretched and three major optical effects were observed simultaneously. First, the fluorescence anisotropy increased, which indicates a reorientation of the fluorophores within the matrix. Second, the fluorescence lifetime decreased by approximately 2.5% (25 ps). Finally, we observed an increase in the emission energy of about 0.2% (corresponding to a blue-shift of 1.2 nm). In addition, analogous measurements with Rhodamine 123 as an inert reference dye showed only minor effects, which can be attributed to matrix effects due to refractive index changes. To relate the observed spectroscopic changes to the underlying changes in molecular properties, quantum-chemical calculations were also performed. Semiempirical methods had to be used because of the size of the OPV5 chromophore. Two conformers of OPV5 (C(2) and C(i) symmetry) were considered and both gave very similar results. Both the observed blue-shift of fluorescence and the reduced lifetime of OPV5 under tensile stress are consistent with the results of the semiempirical calculations. Our study proves the feasibility of fluorescence-based local force probes for polymers under tension. Improved optical sensors of this type should in principle be able to monitor local mechanical stress in transparent samples down to the single-molecule level, which harbors promising applications in polymer science and nanotechnology.

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Section: à3mentioning

confidence: 99%

Fluorophores as Optical Sensors for Local Forces

et al. 2009

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“…1(D)], indicating that the conjugated length of the product was ϳ 8. 11 With reaction time increasing, the fine structures of the spectrum became unclear, whereas the overall absorption became stronger and broader. Simultaneously, the maximum of the spectrum shifted to a longer wavelength.…”

Section: Uv/visible Spectramentioning

confidence: 98%

“…Longer conjugated segments tend to have enhanced absorptions of CAC at lower frequencies and ␦ ACH bands at higher frequencies. 11,14 The spectrum of the DPVC prepared by the catalyzation of glycol also showed polyene bands [ Fig. 2(B)].…”

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confidence: 98%

Poly(ethylene glycol)s catalyzed two-phase dehydrochlorination of poly(vinyl chloride) with potassium hydroxide

Guo

Shi

et al. 1998

J. Appl. Polym. Sci.

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Poly(ethylene glycol)s [HO(CH 2 CH 2 O) n H, where n Ͼ 3] are highly active and selective in catalyzing dehydrochlorination of poly(vinyl chloride) in organicaqueous hydroxide two-phase systems. Their catalytic activity and stability are much higher than those of widely used quaternary ammonium or phosphonium compounds. Poly(vinyl chloride) can be extensively dehydrochlorinated within half an hour at room temperature. The products are polyacetylene-like and have long polyene sequences according to their UV/visible, FT-Raman, and FT-infrared spectra. They can be doped by iodine to conductive states, with conductivities of 1-4 S cm Ϫ1.

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“…Polarized absorption spectra were obtained using Glan-Thompson polarizers and with the sample oriented at 45°a ngle of incidence. For a sample with in-plane isotropy but broken symmetry along the sample normal (symmetry C ∞v ) the polarization dependence of absorption can be quantified by the apparent dichroic ratio D = A s /A p , where A s and A p are the absorbances for s and p (perpendicular and parallel to the plane of incidence, respectively) polarized light [16]. When the sample is at 45°angle of incidence and the transition moment of the molecule is along its long axis [17]:…”

Section: Absorption Measurementsmentioning

confidence: 99%