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 isocyanateblock-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.

Anionic polymerization of n-hexyl isocyanate (HIC) in THF at −98 °C under 10–6 Torr for the kinetic study was performed by the initiation of sodium diphenylmethane (NaDPM) in either the absence or presence of sodium tetraphenylborate (NaBPh4; [NaBPh4]0/[NaDPM]0 = 0 or 5). The common-ion effect of NaBPh4 to suppress the formation of unstable free amidate anions led to termination-free propagation by amidate ion pairs. In [HIC]0/[NaDPM]0 = 50.8/101/201, the initiation of NaDPM early reached ∼100% efficiencies during propagation, which led to the yield of poly­(n-hexyl isocyanate)­s (PHICs) with predictable molecular weights (M n,theo = 6.50/12.7/24.7 kDa; M n = 6.50/12.7/26.1 kDa) and low dispersities (Đ = 1.06/1.07/1.15). Within the conditions, the rate of propagation accorded with a first-order dependence on [NaDPM]0, indicating that the propagating amidate ion pairs are intrinsically unimeric (nonassociated). Kinetics of anionic copolymerization of HIC and allyl isocyanate (AIC) exhibited a monomer distribution toward a tapered block sequence.

An operationally simple approach to preparation of ωnorbornenyl macromonomers (MMs) is reported. Reaction of exo-N-(6hydroxyhexyl)-5-norbornene-2,3-dicarboximide or exo-N-(10-hydroxydecyl)-5-norbornene-2,3-dicarboximide with α-phenyl acrylate (α-PhA) led to novel end-capping agents, NBxPhA [x is 6 (n-hexyl) or 10 (ndecyl)]. Living anionic polymerization of styrene and methyl methacrylate followed by capping with NBxPhA yielded the desired MMs, ω-norbornenyl polystyrene (NBxPS) and ω-norbornenyl poly-(methyl methacrylate) (NBxPMMA). These MMs, formed with controlled molecular weights (M n = 2−5 kDa) and low dispersity (Đ = 1.02−1.07), upon ring-opening metathesis polymerization (ROMP) resulted in P(NB-g-PS) and P(NB-g-PMMA) bottlebrush homopolymers with ∼95% and ∼75% yield, respectively, signifying efficient end-capping efficiency. The factors affecting synthesis of NBxPS and NBxPMMA and their subsequent ROMP, such as [NBxPhA]/[sec-BuLi] ratio, the length of alkyl spacer, and varying molecular weights of the macromonomers, were optimized. Well-defined bottlebrush homopolymers with low polydispersity (Đ = 1.02−1.39) were achieved at various degrees of polymerization (DP 50−600). Additionally, copolymerization of the homopolymers through sequential ROMP furnished the bottlebrush block copolymers (M n = 262−1593 kDa, Đ = 1.09−1.32) displaying photonic crystal properties.

To achieve molecular packing of protic-functionalized helical polymers in aqueous solution, we synthesized an amphiphilic helix–coil–helix triblock copolymer (triBCP) composed of polystyrene and dihydroxyl-functionalized polyisocyanates. Poly­(3-(glycerylthio)­propyl isocyanate)-block-polystyrene-block-poly­(3-(glycerylthio)­propyl isocyanate), P3GPIC-b-PSt-b-P3GPIC, was synthesized by postpolymerization modification. The bidirectional anionic block copolymerization of styrene (St) and allyl isocyanate (AIC) yielded triBCPs, poly­(allyl isocyanate)-block-polystyrene-block-poly­(allyl isocyanate)­s (PAIC-b-PSt-b-PAICs), with well-controlled molecular weights (M n = 5.60–99.9 kDa) and narrow dispersities (Đ = 1.14–1.18). Of them, one with the lowest MW (M n = 5.60 kDa, Đ = 1.14), which was highly organic-soluble, was utilized in the thiol–ene click reaction between allyl group and 1-thioglycerol, producing P3GPIC-b-PSt-b-P3GPIC. The amphiphilic P3GPIC-b-PSt-b-P3GPIC self-aggregated to form spherical vesicles with an average hydrodynamic diameter of 170 nm in aqueous solution, demonstrating that hydrophilic–helical P3GPIC blocks well interacted with water media maintaining their intermolecular packing.

Furfuryl isocyanate (FIC), allyl isocyanate (AIC), and n-hexyl isocyanate (HIC) that have different β-carbon substituents were employed as monomers in living anionic homo- and copolymerization. The rate constants of the self- and cross-propagation reactions were determined, and their comparison showed the electrophilicity order of isocyanate as FIC > AIC > HIC. The kinetic analysis revealed that the anionic copolymerization of FIC:HIC, AIC:HIC, and FIC:AIC generated three different sequence-controlled polyisocyanate copolymers, poly­(furfuryl isocyanate-block-n-hexyl isocyanate) (P­(FIC-b-HIC)), poly­(allyl isocyanate-tapered block-n-hexyl isocyanate) (P­(AIC-tb-HIC)), and poly­(furfuryl isocyanate-gradient-allyl isocyanate) (P­(FIC-grad-HIC)), respectively. The homogeneous sequential anionic copolymerization of the binary isocyanate mixtures generated the polyisocyanate copolymers having repeated monomer sequences. A series connection of P­(FIC-b-HIC), P­(AIC-tb-HIC), and P­(FIC-grad-HIC) segments in the copolymer was attempted by heterogeneous sequential anionic copolymerization of the binary isocyanate mixtures. The variation of the comonomer addition order allowed the resulting polyisocyanate copolymers to be encoded by the three combined monomer sequences.