Blocked isocyanates III: Part A. Mechanisms and chemistry

Nanoencapsulation of blocked isocyanates through aqueous emulsion polymerization

“…The DSC thermograms shown in this paper were all recorded on closed pans. The thermal behaviors of both processes were similar except for the lack of exothermic responses in the open samples, which reflect the effect of crosslinking on the deblocking behavior and the reversible nature of blocked isocyanates establishing an equilibrium in sealed pans, which is consistent with the observations reported by Wicks [13].…”

Preparation and Characterization of Polyurethane Bioadhesive from Hydroxyl-terminated Polylactide and Imidazole-blocked Isocyanate

“…This was due to differences in sample pans and thermal effects in these two instruments. 7 Compared to the DSC results, the deblocking temperature measured by TGA is slight greater in our research.…”

“…7,8 The main feature of isocyanate chemistry is their high reactivity toward nucleophiles, e.g., reaction with alcohols to form urethanes readily occurs at room or slightly higher temperatures, and this is the basis of polyurethane technology. 9 However, in certain situations, this high reactivity, particularly toward water, can be a problem.…”

Rotaxane Building Blocks bearing Blocked Isocyanate Stoppers: Polyrotaxanes through Post‐Assembly Chain Extension

“…[4] At elevated temperatures (> 150 8C), however, they react rapidly with amino or hydroxy difunctional comonomers to produce polyureas and polyurethanes. Blocked isocyanate rotaxane derivatives can thus act as cheap and readily accessible building blocks for polyrotaxane topological analogues of a wide range of commercial polymer systems.…”

“…We chose the fumaramide group, which directs the five component assembly of benzylic amide macrocycle-containing rotaxanes from isophthaloyl dichloride and p-xylylenediamine in high efficiency. [8] This modular approach allowed us to attach different combinations of stoppers 1 and 2 onto the monomeric thread to produce rotaxane monomers (3)(4)(5) which, upon reaction with the suitable bisamine comonomer Jeffamine, produced polyrotaxanes of different topologies (Scheme 2).…”