Ideally selective diisocyanate building blocks

Blocked polyisocyanates containing fluorine atoms as crosslinking agents for polyurethane powder coatings

“…The difference in rate constants without catalysis at room temperature amounts to k prim / k sec = 5, whereas in the presence of most Levi's‐acid catalysts, it is k prim / k sec = 12. Greater regioselectivity of diisocyanate correlates with lower polydispersity of the product 19…”

Superhydrophobic Fluorinated Polyurethane Films

“…When zirconium(IV) butoxide is used as the catalyst for the reaction between an alcohol and IMCI, the selectivity of the reaction between the alcohol and the primary isocyanate group is as high as 99% [28]. Therefore, by controlling the F n -OH/NCO molar ratio at 1:2, a perfluoroalkyl chain could be selectively grafted onto IMCI, leaving the other isocyanate group for further reaction.…”

“…According to the stoichiometry for the reaction between IMCI and F n -OH and the selectivity of the Zr-catalyst [28], the OH/NCO molar ratio just needs to be 1/2 to obtain well-defined F n -IMCI. When a coating was prepared with F 8 -IMCI synthesized as such (together with SLO and N3300), the water contact angles on the coating varied significantly before and after the samples were rinsed with acetone.…”

“…Since the primary NCO is much more reactive than the tertiary NCO in the presence of the Zr-catalyst we used (the selectivity is above 99% [28]), there should be no F 8 -IMCI-F 8 present in the final product. The remaining IMCI can act as a chain extender in the following film formation.…”

Urethane reaction kinetics of butanediols catalyzed by Zr(acac)4

“…A few researchers have reported the catalytic properties of zirconium chelate for the urethane reaction kinetics and mechanism 4–9. For example, Blank et al4, 5 investigated the reaction of alcohol or water with isocyanate with zirconium chelate as catalyst.…”