Anionic Polymerization of Reactive 3‐Chloropropyl Isocyanate

Abstract

Summary For the synthesis of a new functional polyisocyanate, the anionic polymerization of 3‐chloropropyl isocyanate (3CPIC) was carried out using several initiator systems in THF at −98 °C. When a sodium benzanilide (Na‐BA) cluster was used as an aggregated initiator, the initiation efficiency and polymer yield were low due to too fast propagation and cyclic trimerization compared to the initiation. A more reactive oligo(n‐hexyl isocyanate)sodium/Na‐BA cluster improved the initiation efficiency and polymer yield, but trimerization still occurred. A nearly quantitative yield was achieved by oligo(2‐vinylpyridinyl)potassium in the presence of a large excess of sodium tetraphenylborate (NaBPh4). In this case, highly dissociating and bulky NaBPh4 reduced the propagation rate and protected the propagating chain end from trimerization through steric hindrance. This advantage of NaBPh4 was cancelled by the decreased initiation efficiency. All polymerization trials resulted in uncontrolled molecular weight properties. The chloropropyl side groups of the obtained P3CPIC reacted with polystyryllithium to generate poly(3‐chloropropyl isocyanate)‐graft‐polystyrene (P3CPIC‐g‐PS) through the grafting‐onto method.

Propagation-Inspired Initiation of an Aliphatic Sodium Amidate for the Living Anionic Homo- and Copolymerization of Isocyanates: Access to the Multiblocky Sequence Distribution of Binary Comonomers

“…The common synthetic methods for polyisocyanates are the anionic polymerization − and organotitanium­(IV)-catalyzed coordination polymerization of isocyanates. − We consider that the former is better suited in controlling the monomer sequence of copolymer by the choice of comonomers. − The kinetics of propagation reaction depends greatly on the structural factors of monomer, such as steric hindrance and electron-donating/withdrawing effect of substituent. The propagating ion pairs of polyisocyanates (amidate ion pairs) are tolerant to a wide variety of functional groups except protic groups due to their weak nucleophilicity. , This factor allows the anionic polymerization of many types of functional isocyanates. − …”

Fundamental Kinetics of Living Anionic Polymerization of Isocyanates Emerging by the Sodium Diphenylmethane-Mediated Initiation

“…Although the noticeable progress in the anionic polymerization of isocyanates has brought a structural diversity of polyisocyanate-containing macromolecules, ,− the mechanistic pathway of propagation has been veiled until now due to a lack of understanding for the equilibrium of propagating amidate species. This issue might have been a main reason for the rare attention to the control of monomer sequence despite many approaches to the copolymerization. − It is believed that the development of propagation rate law is potentially important in the kinetic control to develop novel polyisocyanate copolymers with various monomer sequence distributions.…”

Synthetic Control of Helical Polyisocyanates by Living Anionic Polymerization toward Peptide Mimicry

“…Direct polymerization of hydrophilic isocyanate has also been studied . Living anionic polymerization was applied to several carbamate-containing isocyanates.…”

“…175−177 Direct polymerization of hydrophilic isocyanate has also been studied. 178 Living anionic polymerization was applied to several carbamate-containing isocyanates. As a result, poly(npentanoxycarbonylaminohexyl isocyanate) (PPEAHI) with long alkyl chains showed exceptionally well-controlled molecular weights and low dispersities.…”