Polymerization of Styrene Derivatives Using Anilinonaphthoquinone‐Ligated Nickel Complexes and Thermal/Rheological Properties of the Produced Polymers

Abstract

Polystyrenes (PStX, X = H, OMe, Me, or Cl at 4‐position) are synthesized by the use of anilinonaphthoquinone‐ligated nickel complexes [Ni(C10H5O2NAr)(Ph)(PPh3): 1a, Ar = C6H3‐2,6‐iPr; 1b, Ar = C6H2‐2,4,6‐Me; 1c, Ar = C6H5] activated with modified methylaluminoxane (MMAO) in toluene. The polymer yield is dependent on the substituent X and decreases in the following order: OMe > Me > H >> Cl. The highest weight‐average molecular weight (Mw) of 107 000 with polydispersity (Ð) of 1.4 is achieved for PStOMe by the 1a‐MMAO catalytic system. 13C NMR analysis indicated that the polymers obtained at 70 °C are atactic but those obtained at 0 °C are isotactoid (isotactic triad ≈ 74 ̶ 82 %), which depended on X. The linear viscoelasticity measurement is also performed to investigate the influences of the substituent on the rheological properties. The critical molecular weight of the chain entanglement of PStOMe is higher than that of PStMe, which should be due to the suppression of the chain entanglement by the methoxy group.