The polymerization of(-)-p-[(tert-butylmethylphenyl)silyl] phenylacetylene (t-BuMePhSi*PA) and (+)-p- [(methyl(alpha -naphthyl)phenyl)silyl]phenylacetylene (MeNpPhSi*PA) with the [(nbd)RhCl](2)-Et3N catalyst yielded polymers with very high molecular weights over 2 x 10(6) in high yields. The optical rotations of the formed poly(t-BuMePhSi*PA) and poly(MeNpPhSi"PA) were as high as -356 and -150 degrees (c = 0.11 g/dL in CHCl3,), respectively. The circular dichroism (CD) spectrum of poly(t-BuMePhSi*PA) in CHCl3, exhibited very large molar ellipticities ([theta]) in the UV region: [theta](max) = 9.2 x 10(4) degrees .cm(2).dmol(-1) at 330 nm and -8.0 x 10(4) degrees .cm(2).dmol(-1) at 370 nm. The [theta](max) values of poly(MeNpPhSi*PA) were also fairly large: [theta](max) = 7.1 x 10(4) degrees. cm(2).dmol(-1) at 330 nm and -5.3 x 10(4) degrees .cm(2).dmol(-1) at 370 nm. The optical rotations of poly(t-BuMePhSi*PA) and poly(MeNpPhSi*PA), measured in tetrahydrofuran, chloroform, and toluene solutions, were hardly dependent on temperature in the range 22-65 degreesC. The CD effects of these polymers hardly changed in the temperature range 28-80 degreesC, either. These results indicate that the helical structures of these polymers are thermally appreciably stable. (C) 2000 John Wiley & Sons, Inc.