¹H nuclear magnetic resonance study of polyurethane prepolymers from toluene diisocyanate and polypropylene glycol

Abstract

Polyurethane prepolymers prepared from toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, and polypropylene glycol with a ratio between the isocyanate and hydroxyl groups equal to 2 were analyzed by 1 H nuclear magnetic resonance (NMR) spectroscopy in acetone-d 6 . Different temperatures and concentrations were used. Toluene 2,4-dimethylurethane and toluene 2,6-dimethylurethane were synthesized and used as model compounds to assign prepolymers signals. Measurements of spin-lattice relaxation time T 1 by "inversion recovery" experiments were carried out on toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, toluene 2,4-dimethylurethane, toluene 2,6-dimethylurethane, and polyurethane prepolymers. Differences in T 1 times were used to interpret prepolymers spectra, by means of the strong observed effect on protons due to the presence of adjacent isocyanate groups.

The phase mixing studies on moisture cured polyurethane-ureas during cure

“…The nucleation step will end as the solvent, 2-ethoxyethyl acetate evaporates. The growth step requires the moisture to migrate, something that is very slow for thick film and, therefore, the possibility exists for biuret and allophanate formation inside the bulk of the polymer [50,51]. Less T min value after a certain cure time for thicker films than the thinner film was observed and suggests that phase mixing for a thick film was less.…”

Dynamic colloidal processes in waterborne two-component polyurethanes and their effects on solution and film morphology

“…While a number of studies have focused on the NMR analysis of polyurethanes and their starting materials, [33][34][35] very few NMR experiments have specifically dealt with waterborne polyurethanes, [36] and there are good reasons for that. WB 2K-PUR dispersions are formulated without the use of organic solvents.…”

Microwave-assisted synthesis of cyclodextrin polyurethanes

“…1c. With the help of 2D NMR, known assignments of related polymers (Dubois, Desilets, Ait-Kadi, & Tanguy, 1995;Pegoraro, Galbiati, & Ricca, 2003), and shift additivity rules (Cheng & Kasehagen, 1994), we were able to provide complete assignments of the 13 C and 1 H spectra; these are shown in Fig. 1a and b. On the 13 C spectrum, it is of interest that the peaks of the carbons ortho to the carbamate substituents on the ring are broadened (i.e., position 1 at ca.…”