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

We report the propagation-inspired initiation of sodium N-phenethyl-3-phenyl­propanamide (NaPEPPA), an aliphatic sodium amidate, for the living anionic homo- and copolymerization of isocyanates. This initiator was compared with sodium benzanilide (NaBA), an aromatic sodium amidate, in the living anionic homopolymerization of n-hexyl isocyanate (HIC). Only NaPEPPA attained the initiation efficiencies close to unity at the early stage of propagation. The homopolymerization with [HIC]0/[NaPEPPA]0 = 38.9/85.1/203 led to poly­(n-hexyl isocyanate)­s (PHICs) with predictable MWs and low dispersities (M n,theo = 5.12/10.7/24.7 kDa; M n = 5.22/11.1/27.4 kDa; Đ = 1.11/1.10/1.06). NaPEPPA was also used to initiate the living anionic copolymerization of HIC and furfuryl isocyanate (FIC). As a result, poly­(furfuryl isocyanate-block-n-hexyl isocyanate) (P­(FIC-b-HIC)) was afforded by the blocky monomer sequence distribution. Based on the copolymerization kinetics, a series of polyisocyanate-based multiblock copolymers, P­(FIC-b-HIC)1/P­(FIC-b-HIC)2/P­(FIC-b-HIC)3/P­(FIC-b-HIC)4 (M n,theo = 5.47/10.6/15.8/20.8 kDa; M n = 5.59/11.5/16.3/20.3 kDa; Đ = 1.10/1.03/1.03/1.03), were afforded by the repetitive sequential addition of comonomers.