Utilization of a Kinetic Principle of the Sequence-Controlled Anionic Copolymerization of Isocyanates toward Polyisocyanate Copolymers Encoded with Multiple Monomer Sequences

摘要

Furfuryl isocyanate (FIC), allyl isocyanate (AIC), and nhexyl isocyanate (HIC) that have different beta-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.