Selective complete decomposition of poly(n‐hexylisocyanate) and its use in a new molecular design method

Abstract

Poly(n‐hexylisocyanate) (PHIC‐NH) as a rod‐like polymer having a NH group at one end of the polymer chain was found to instantly (less than a few seconds) be completely decomposed by CH3O−Na+ in tetrahydrofuran/CH3OH under a mild experimental condition ([CH3O−Na+] < 1 mol L−1 at room temperature).The mechanism of the decomposition for the PHIC‐NH consists of two steps: the first is abstraction of the proton for PHIC‐NH by Na+ with a slow reaction rate, and the second is the consequent depolymerization of PHIC‐N− based on the equilibrium polymerization with a rapid depolymerization rate. The decomposition rate constants (kd) depend on Mw of PHIC‐NH, namely kd ∼ Mw−1.0. The decomposition of the PHIC‐NR having an end‐capped NR group was completely depressed. Using an “all or nothing” mechanism for the decomposition, the (PHIC)3.43 comb‐shaped polymer and polystyrene (PSt)‐graft‐(PHIC‐NH)4.28 graft copolymer were, respectively, decomposed to produce (PHIC‐NH)3.43–1.03 and PSt‐graft‐(PHIC‐NH)4.28–0 in a series with different numbers of PHIC‐NH combs and PHIC‐NH grafts by regulating the amount of CH3O−Na+ and the decomposition time. Molecular structure of (PHIC‐NH)3.43–1.03 and PSt‐graft‐(PHIC‐NH)4.28–0 was discussed from a viewpoint of PSt‐reduced chain dimension per molar mass. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011