Deuterated and Ring-opening Metathesis Polymerization of Cyclooctadiene,and Solid-state Catalytic Addition of Its Polymers
Deuterated(tritiated)polymers are a type of promissing target materials for inertial confinement fusion.To prepare deuterated polymers with more tritium addition sites,in this work,the deuteration and ring-opening metathesis polymerization of cyclooctadiene was investigated.The mechanism for deuteration reaction of 1,5-cyclooctadiene was studied by analyzing the components of intermediate products during the reaction process.The results of magnetic resonance spectroscopy(1H-NMR,2H-NMR and 13C-NMR)showed that the by-product of deuterated cyclooctadiene was deuterated cyclooctadiene.The effects of temperature,additives and reaction time on the deuteration rate of products and the yields of by-products were studied,and then the optimized reaction conditions were obtained.Deuterated 1,3-cyclooctadiene with a high deuteration rate up to 96％was prepared.The experiment of ring-opening metathesis polymerization of(deuterated)1,3-cyclooctadiene was carried out.The existence of a large number of continuous conjugated double bonds led to the crystallization of the polymer,resulting in a poor solubility.In the presence of 5 wt％Pd/BaSO4 and Grubbs second generation catalyst,solid-state catalytic deuteration experiments of poly(1,3-cyclooctadiene)and the copolymers of deuterated 1,3-cyclooctadiene and deuterated cyclooctadiene were carried out.The polymer chain can be added to near saturation with D2,accompanied by obvious hydrogen isotope exchange reaction.A homogeneous solid-phase catalytic hydrogen isotope addition method has been developed.By this method,the well processed deuterated polymer target pellets can be added with tritium directly,and thus the deuterium-tritiated polymer target pellets can be prepared.
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