Quantitative analysis of polymer mixtures in solution by pulsed field-gradient spin echo NMR spectroscopy

The lognormal and gamma distribution models for estimating molecular weight distributions of polymers using PGSE NMR

“…The stretched exponential model can provide some measure of polydispersity, but it is difficult to interpret in terms of a distribution of diffusion coefficients [18,19]. Van Lokeren et al [20] discuss determining the molecular weight distribution on binary and ternary polymer mixtures, taking relaxation effects into account. In all, NMR is a promising technique for determining molecular weight distributions of polymers, and an interesting alternative to standard methods such as gel permeation chromatography (GPC) and dynamic light scattering (DLS).…”

Quantitative Analysis of D-(+)-Glucose in Fruit Juices Using Diffusion Ordered-1H Nuclear Magnetic Resonance Spectroscopy

“…DOSY-NMR is a two-dimensional (2D) NMR approach, in which compounds with different diffusion coefficients (D) at an appropriate pulsedfield gradient strength can be separately monitored at the 2D DOSY spectra. 11 Indeed, the DOSY-NMR method based on the pulse-gradient spin-echo technique has been challenged to the quantitative analysis of polystyrene, 12 poly(hydroxyethyl cellulose) and diethyleneglycol monobutylether, 13 by overcoming the disadvantage of the algorism, which is greatly influenced by the assay conditions such as solution viscosity and temperature, etc. However, there have so far been few reports on the DOSY method for food analysis.…”

Regioselective Synthesis of Thiophene-Based Poly(arylenevinylene)s via Co-Catalyzed Hydroarylation Polyaddition

“…To calculate M n using 1 H NMR spectroscopy, the longitudinal relaxation time (T 1 ) of Paa was measured. 28 The longest measured value of T 1 was 2.6 s at the 3,3′-positions of the bithiophene unit. The optimized relaxation time for quantitative 1 H NMR spectroscopy was estimated to be approximately 10 s. Quantitative 1 H NMR spectra were measured for each PAV to calculate the M n values from the accurate integral ratios of the signals of the repeating units (7.1 ppm for 3,3′-positions of bithiophene unit) to those of each terminal unit (7.4 ppm for the 5-position of terminal thiophene unit and 3.2 ppm for terminal alkyne unit).…”

“…Because of the low solubility of Pad , the hydroarylation polyaddition of 1a with 4d was performed using a lower concentration (0.02 M in DCE (entry 4)). To calculate M n using 1 H NMR spectroscopy, the longitudinal relaxation time ( T 1 ) of Paa was measured . The longest measured value of T 1 was 2.6 s at the 3,3′-positions of the bithiophene unit.…”