Synthesis And Properties Of Cyclic Olefin Polymers

Cyclic olefin polymers are one of the most important engineering plastics.Because of their excellent transparency,chemical corrosion resistance,low moisture absorption and so on,it can be widely used in electronic devices,drug packaging,optical prism and other fields.However,poor heat resistance or poor toughness usually existed in commercial cyclic olefin polymers,so we need to improve the toughness and heat resistance of the cyclic olefin polymers simultaneously.Bulky exo-1,4,4a,9,9a,10-hexahydro-9,10?1',2'?-benzeno-l,4-methanoanthracene?HBM?was synthesized by Diels-Alder reaction of norbornadiene and anthracene.Then the ring opening metathesis polymerization of HBM was conducted using low-cost and efficient WCl₆/i-Bu₃Al/ethanol/1-hexene catalyst system.The influence of the amount of hexene on the molecular weight of polymer was investigated,and the optimal monomer/hexene was finally determined to be 1000.Then,the copolymerization of HBM with dicyclopentadiene?DCPD?was studied.By adjusting the amount of i-Bu₃Al and ethanol of the catalyst system,a series of HBM/DCPD copolymers with different HBM content?30-100%?were obtained with100%yield and no gel.¹H NMR indicated that HBM content in the copolymer is consistent with the feed ratio.All copolymers were hydrogenated by chemical method and saturated polymers were obtained.The polymers exhibited excellent properties,molecular weight is up to 10⁵ orders of magnitude.Glass transition temperature?T_g?can be adjusted in the range of 151.7-219.7°C,and thermal decomposition temperature can reach 340°C.Tensile tests showed that the toughness of the polymers were improved obviously by the copolymerization of HBM with less bulky DCPD,and the elongation at break was increased from 2.1%to 15.8%.Besides,all polymer films exhibited excellent transparency,the transmittance was higher than 80%in the range of 400-800 nm.In addition,the copolymerization behavior of HBM and norbornene?NBE?was also explored.A series of HBM/NBE copolymers with different HBM content?40-90%?were synthesized.Hydrogenated HBM/NBE copolymers exhibit excellent performance similar to HBM/DCPD copolymers,with its molecular weight up to 10⁵orders of magnitude.Glass transition temperature?T_g?can be adjusted in the range of117.5-206.2°C,and thermal decomposition temperature can reach 340°C.With the increase of NBE content,the strain at break of polymer materials increased gradually from 4.4%to 14.8%.Besides,for all polymer films,the transmittance was higher than 80%in the range of 400-800 nm and did not decrease at high NBE content.