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Neodymium chloride isopropanol complex(NdCl_3·3~iPrOH) activated by modified methylaluminoxane(MMAO) was examined in isoprene polymerization in hexane,with regards to Nd compounds,aluminum(Al) compounds,[Al]/[Nd] ratio,polymerization temperature and time.NdCl_3-3~iPrOH exhibited high activity producing polymers featuring high cis-1,4 stereospecificity(>96%),very high molecular weight(M_n>1.0×10~6) and fairly narrow molecular weight distribution (MWD,M_w/M_n<2.0) simultaneously.In comparison,neodymium isopropoxide also showed high activity providing polymers with narrow MWD(M_w/M_n = 2.07),but somewhat low cis-1,4 content(ca.92%),while neodymium chloride had no activity under present polymerization conditions.The Al compounds affected the polymer yield in the order of Al(i-Bu)_3>MMAO>Al(i-Bu)_2H.MMAO as cocatalyst afforded polyisoprene with high M_n over 1.0×10~6,whereas as stronger chain transfer agent than MMAO,Al(i-Bu)_3 and Al(i-Bu)_2H yielded polymers with low M_n(1.0×10~5-8.0×10~5). NdCl_3·3~iPrOH/MMAO catalyst showed a fairly good catalytic activity even at relatively low[Al]/[Nd]ratio of 30,and the produced polymer remained high cis-1,4 content of 95.8%along with high M_n over 1.0×10~6 even at elevated temperatures up to 70℃.The polymerization rate is of the first order with respect to the concentration of isoprene.The mechanism of active species formation was discussed preliminarily.
Neodymium chloride isopropanol complex (NdCl_3 · 3 ~ iPrOH) activated by modified methylaluminoxane (MMAO) was examined in isoprene polymerization in hexane, with regards to Nd compounds, aluminum (Al) compounds, [Al] / [Nd] ratio, polymerization temperature and NmCl_3-3 ~ iPrOH exhibited high activity producing properties with high cis-1,4 stereospecificity (> 96%), very high molecular weight (M_n> 1.0 × 10 -6) and fairly narrow molecular weight distribution (MWD, M_w / Neodymium isopropoxide also showed high activity providing polymers with narrow MWD (M_w / M_n = 2.07), but somewhat low cis-1,4 content (ca.92%), while neodymium chloride had no activity (i-Bu) _2H.MMAO as cocatalyst afforded polyisoprene with high M_n over 1.0 × 10 -6, while the polymerization yield of the Al compounds affected the polymer yield in the order of Al (i-Bu) _3> MMAO> As stronger chain transfer agent than MMAO, Al (i-Bu) _3 and Al (i-Bu) _2Hyielded polymers with low M_n (1.0 × 10 ~ 5-8.0 10 ~ 5). NdCl_3 · 3 ~ iPrOH / MMAO catalyst showed a fairly good catalytic activity even at relatively low [Al] / [Nd] ratio of 30, and the produced polymer remained high cis-1,4 content of 95.8% along with high M_n over 1.0 × 10 -6 even at elevated temperatures up to 70 ° C. The polymerization rate is of first order with respect to the concentration of isoprene.The mechanism of active species formation was discussed preliminarily.