Synthesis, structure, and properties of poly[1-(trimethylgermyl)-1-propyne]

Polymerization of 1-(trimethylgermyl)-1-propyne (TMGP) with TaCl₅ and NbCl₅ produced a colorless polymer in high yields, whose molecular weight reached about 3 × 10⁵-14 × 10⁵. The molecular weight distribution of the poly(TMGP) with NbCl₅ in cyclohexane was somewhat narrow (M_w/M_n = approx. 1.54). The TaCl₅-based poly(TMGP) dissolved in toluene, chloroform, cyclohexane, carbon disulfide, carbon tetrachloride, tetrahydrofuran, hexane, and so forth; the NbCl₅-based polymer was less soluble and did not dissolve in hexane, despite its lower molecular weight. The cis contents of the NbCl₅- and TaCl₅-based poly(TMGP)s determined by ¹³C NMR were 67 ± 5 and 28 ± 3%, respectively. The onset temperature of the weight loss of poly(TMGP) in air was 350°C, indicating fair thermal stability. The oxygen permeability coefficient (P_O(2)) of poly(TMGP) at 25°C was 7800 barrer after the methanol conditioning, and the permeability was fairly stable to aging.