Blocked isocyanates: from analytical and experimental considerations to non-polyurethane applications

Abstract

In this review we aim to provide an introductory guide to blocked isocyanates, through discussion on different examples of blocking groups, along with experimental considerations for their application.

Preparation and Characterization of Soybean Oil-Based Polyurethanes for Digital Doming Applications

“…IPDI prepolymers are widely used for the synthesis of rigid polyurethanes, due to the presence of cyclohexane ring, but they can also be replaced with more flexible linear aliphatic diisocyanates such as 1,6-Hexamethylene diisocyanate (HMDI) and Dicyclohexylmethane-4,4′-diisocyanate (H12MDI) (Table 2) [29,33]. …”

“…With the whole set of selected reactants in hand (soy-based polyol, fossil Alcupol R3810, diisocyanate H12MDI, and catalysts K22), we searched for the best formulation of Bio-based polyurethane for doming applications, by mixing in several ratios the soy-based Bio-polyol and its fossil counterpart (Alcupol R3810) [33,34]. …”

Fluoride‐Catalyzed Deblocking: A Route to Polymeric Urethanes

“…[12,13] Polyurethane properties are tailored by monomer selection, [14][15][16] involving diisocyanates,d iols,a nd/or polyols. [18,19] "Blocked" isocyanates,o btained by reacting isocyanates with alcohols,are more stable and less toxic, and serve as isocyanates urrogates in polyurethane synthesis. [18,19] "Blocked" isocyanates,o btained by reacting isocyanates with alcohols,are more stable and less toxic, and serve as isocyanates urrogates in polyurethane synthesis.…”

“…[18,19] "Blocked" isocyanates,o btained by reacting isocyanates with alcohols,are more stable and less toxic, and serve as isocyanates urrogates in polyurethane synthesis. [17][18][19] Solvents and co-reactants induce disparities in deblocking temperatures,w ith higher temperatures promoting isocyanurate formation and degradation. [17][18][19] Solvents and co-reactants induce disparities in deblocking temperatures,w ith higher temperatures promoting isocyanurate formation and degradation.…”

“…[17] However, even conventional polyurethane chemistry carries significant challenges,i ncluding moisture sensitivity and toxicity of the isocyanate monomers. [18,19] "Blocked" isocyanates,o btained by reacting isocyanates with alcohols,are more stable and less toxic, and serve as isocyanates urrogates in polyurethane synthesis. [20][21][22] At elevated temperature and in the presence of ac atalyst, losing the blocking group regenerates the isocyanate,w hich then polymerizes with diols or polyols.T his chemistry presents its own complexities by requiring high deblocking temperatures and variable success depending on the selected isocyanate, solvent, catalyst, and blocking moiety.…”