可溶性稀土聚乙炔的合成及其聚合机理的研究

研究了各种催化体系、催化剂浓度及聚合条件对催化效率(f)和聚乙炔分子量()的影响。发现Nd(i-OC_3H_7)-AlR_3(R=C_2H_5,i-C_4H_9)催化体系可获得较大的可溶分数(q)。催化剂浓度、Al/Nd克分子比和聚合温度对f、及q均有一定影响。可溶性Nd(i-OC_3H_7)_3-AlR_3催化体系的UV光谱证实、Nd的价态与AlR_3混合与AlR_3混合后保持不变。PA的IR光谱示出,Nd(i-OC_3H_7)_3-Al(C_2H_5)_3及Nd(i-OC_3H_7)_3-Al(i-C_4H_9)_3体系获得的聚合物分别含有CH_3CH_2—和(CH_3)_2CHCH_2—末端基。上述结果表明,乙炔的聚合可能是通过单体在Nd-C键之间的插入进行的。

SYNTHESIS OF SOLUBLE POLYACETYLENE AND INVESTIGATION OF POLYMERIZATION MECHANISM

Effect of various catalyst systems, catalyst concentration and polymerization conditions on the catalytic efficiency (f) and molecular weight (Mn) of polyacetylene (PA) was investigated, it is found that larger amount of soluble fraction (q) of PA was obtained by catalyst systems Nd(i-OC3H7)3-AlR3 (R = C2H5-, i-C4H9). The catalyst concentration, Al/Nd molar ratio and polymerization temperature exert an influence on the f, Mn and q. UV spectra of soluble catalyst systems Nd(i-OC3H7)3-AlR3 confirmed that the valence state of Nd remains unchanged after mixing it with AlR3. Results of IR spectra of PA showed that polymer obtained with Nd (i-OC3H7)-Al(C2H5)3 and Nd(i-OC3H7),-Al(i-C4H8)3 contained CH3CH2- and (CH3)2 CHCH2- end group respectively. The above mentioned results and the fact that CH2 = CH-end group was observed for polymers indicated that polymerization of acetylene with studied catalysts might be carried out through insertion of monomer between Nd-C bond.