Dynamic Infrared Linear Dichroism Study of Poly(p-Phenylene Vinylene) and its Precursor

Abstract

Poly(p-phenylene vinylene) (PPV) has many interesting electrical properties, particularly anisotropic conductivity upon uniaxial stretching, because of its delocalized π-electron system. In this study we have investigated the mid-infrared response of PPV and PPV-precursor films subjected to modulated uniaxial strain in order to study the degree of molecular motions and their time dependence during deformation. These studies have used a step-scan infrared spectrometer in conjunction with a piezo-driven in situ Polymer Modulator™. The viscoelastic properties are monitored simultaneously with the dynamic infrared vibrational response to the applied perturbation. The major molecular vibrations associated with the stretching of the precursor and of PPV have been identified and their time-dependence studied by using both phase-spectral and two-dimensional infrared (2D-IR) approaches. It has also been shown that the precursor, at ambient temperatures, is elastic in nature. However, after the introduction of conjugation on the backbone via conversion to PPV, the material becomes more viscous; the change is evident at both the microscopic and macroscopic levels.

Advances in two-dimensional correlation spectroscopy

“…DIRLD study of poly(pphenylene vinylene) using a step-scanning FT-IR was described by Shah et al [231]. Phase angle spectra and 2D IR correlation spectra are both presented.…”

Anisotropic Properties of Conducting Polymers Prepared by Liquid Crystal Templating

“…Conducting polymers such as PEDOT prepared by chemical or electrochemical polymerization are poorly ordered, consisting of amorphous material mixed with nanoscale crystalline domains. [12,14,15] Spin-coating and chemical polymerization of PEDOT films can orient polymer chains parallel to the substrate, however orientation within the plane is generally random. [11,13,16] Conducting polymer thin films have been aligned in-plane by Langmuir±Blodgett techniques, by stretching, rubbing, or with alignment layers.…”

“…[11,13,16] Conducting polymer thin films have been aligned in-plane by Langmuir±Blodgett techniques, by stretching, rubbing, or with alignment layers. [12,15,17] However, these techniques add additional processing steps and can present obstacles to incorporation in device architectures. In this work, we use a self-organized template to direct polymerization of EDOT, resulting in oriented polymer chains without the need for rubbing, stretching, or other mechanical alignment.…”

Characterization of an Optoelectronic Polymer, Poly(2-Phenoxy p-Phenylene Vinylene), and its Precursor Polymer by Dynamic Infrared Spectroscopy

“…W hile this relatively new technique has m any uses in polymer chemistry, little application has been made in the eld of conjugated conducting polymers. 12 Conjugated conducting polymers, also known as synthetic metals and more commonly conducting polymers, have attracted m uch interest for their high electrical conductivities 13 and optoelectronic properties. 14 Since the discovery of conductivity in doped polyacetylene in 1977, 15 much research has focused on the synthesis and development of these m aterials.…”

“…The experimental setup was similar to that described previously. 12 Dynamic strain was applied to the sample by a piezo-driven Polymer M odulatory m icrorheometer (M anning Applied Technology, Moscow, ID). A sinusoidal signal produced by an Agilent 33120A Function Generator/Arbitrary Waveform Generator was used to drive the Polym er M odulatory microrheometer.…”