MW dependence of dendron-jacketed polymers has been explored using polyvinyl
ethers with narrow MW distribution. PVE-1 always forms a Col h phase, regardless of
the DP (3.7–16). It was suggested that with a DP < = 4, the dendrons self-assemble into
discs that stack to form a Col h phase. With a DP > 4, each polymer chain forms
a column, with the main-chain threads through the center (Percec et al. 1992a).
In contrast, PVE-2 forms a Col h phase above the melting point of the underlying
crystalline phase at low DP (3.2–3.9), where columns form in the same way as in low
DP PVE-1. However, PVE-2 is amorphous at DP > 5. At DP % 5, the polymer displays
a Col h phase and a reentry isotropic phase (Percec et al. 1992b).
PECH
POBN
PMAI
Chart 8 Structures of columnar LC phase-forming polymers carrying a three-tailed minidendron
m = 1: R 1 = -C 12 H 25
m = 2: R 2 = -C 5 H 11
m = 3: R 3 = -CH 2 CH(CH 3 )C 2 H 5
Y =CH 2 , C=O
m = 1: A 1 =
L 1 = C 3 H 6
m = 2: A 2 =
L 2 = C 3 H 6
m = 3: A 3 =
L 3 = C 11 H 22
m = 1: R 1 = -C 12 H 25
m = 2: R 2 = -C 5 H 11
m = 3: R 3 = -CH 2 CH(CH 3 )C 2 H 5
PVE-1
PVE-2
3,4,5-PS
3,4-PS
3,5-PS
BBPBPMA-11
BPMA-m, m = 1-4
BPPMA-4
NPMA-4
Chart 9 Structures of columnar LC phase-forming polymers carrying minidendrons with added
rigid-rod units
5 Columnar Phase-Forming Polymers
137