Use of solid state NMR to probe the order, dynamics and conformations of poly(p-phenylene vinylene) and poly(2,5-dimethoxy-p-phenylene vinylene). [NMR (nuclear magnetic resonance)]

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:5257334

Simpson, J H

Solid-state [sup 13]C cross-polarization magic-angle-spinning (CPMAS) nuclear magnetic resonance (NMR) spectra have been obtained for films of poly (p-phenylene vinylene) (PPV) and PPV-d[sub 4], poly (p-2,3,5,6-tetradeutero-phenylene vinylene). All four phenylene and vinylene resonance have been assigned. The [sup 13]C CPMAS NMR spectra show the presence of phenylene ring 180[degrees] rotation jumps. Solid-state [sup 2]H quadrupole-echo nuclear magnetic resonance spectra of PPV-d[sub 4] films show that all the phenylene rings of PPV undergo 180[degrees] rotational jumps about the 1,4 ring axis with a median activation energy of 15 kcal/mo. The effects of concentrated sulfurice acid doping of PPV-d[sub 4] have been examined with [sup 2]H quadrupole echo NMR spectroscopy. Stretched PPV films have been prepared in which the vinylene protons have been substituted with deuterium (PPV-d[sub 2]). [sup 2]H spectra of aligned samples at high temperature show molecular motion. [sup 2]H quadrupole echo NMR spectra of oriented PPV-d[sub 4] aligned in the NMR magnetic field have been simulated and have yielded the chain orientation distribution in these films. [sup 2]H spectra obtained at [minus]58[degrees]C are well simulated by an orientation distribution consisting of two Gaussian components. PPV has been doped with sodium metal. The chemistry of this process has been examined with elemental analysis. ESR spectroscopy has followed the evolution of unpaired spins as the doping reaction proceeds. Two-dimensional [sup 13]C-[sup 1]H HETCOR CP-MAS NMR spectra of p-dimethoxybenzene (DMB) and poly(2,5-dimethoxy-p-phenylene vinylene) (PDMPV) with variable [sup 1]H dipolar mixing times have been analyzed to determine the rates of [sup 1]H magnetization transfer between chemically distinct protons. Internuclear distances have been obtained from these rates and the conformation of the PDMPV repeat unit has been calculated and discussed.

• Research Organization: Massachusetts Inst. of Tech., Cambridge, MA (United States)
• OSTI ID: 5257334
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
MOLECULAR STRUCTURE
DYNAMICS
POLYPHENYLS
NUCLEAR MAGNETIC RESONANCE
POLYVINYLS
CARBON 13
DEUTERIUM
ELECTRON SPIN RESONANCE
STRUCTURAL CHEMICAL ANALYSIS
AROMATICS
CARBON ISOTOPES
EVEN-ODD NUCLEI
HYDROCARBONS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MECHANICS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERS
RESONANCE
STABLE ISOTOPES
400201* - Chemical & Physicochemical Properties
360602 - Other Materials- Structure & Phase Studies