Polymerization of norbornene (NBE) was carried out using scandium phosphonate (Sc(P204)3) combined with alkyl aluminium as catalysts.13C-NMR

1H-NMR and FTIR analyses indicate that the PNBE are mainly prepared by the ring-opened type polymerization

and also show ring-retention to varying degrees in this type of catalytic system.It was found that alkyl aluminium cocatalyst plays an important role in the polymerization.Catalyzed by Sc(P204)3/Al-iBu3 system under the optimal polymerization conditions:n(Al)/n(Sc)=5 aging at 50℃ for 2 h

n(NBE)/n(Sc)=50

polymerization at 80℃ for 4 h producing a insoluble and crosslink polymer with 39% yield was obtained.While AlEt3 was used as cocatalyst

the PNBE obtained are partly soluble in organic solvents with 98% yield under the optimal polymerization conditions:n(Al)/n(Sc)=30 aging at 40℃ for 5 min

n(NBE)/n(Sc)=50

polymerization at 60℃ for 7 h.Measured by GPC

the soluble fraction of PNBE exhibits low molecular weight Mn =2.4103~3.0103 with moderate molecular weight distributions (MWD=1.9~2.2).The soluble fraction of PNBE consists of 81%~88% ring-opened type polymer with 48%~58% cis- double carbon bond content.