94
I. Osaka
S
N
S
S
N
S
R 1
R 1
S
N
S
S
N
S
R 2
R 2
n
PTzBT-10HD
PTzBT-10OD
PTzBT-12HD
PTzBT-12OD
PTzBT-14HD
PTzBT-14OD
Alkyl side chains used in this study:
n-decyl (C10) =
n-dodecyl (C12) =
n-tetradecyl (C14) =
2-ethylhexyl (EH) =
2-butyloctyl (BO) =
2-hexyldecyl (HD) =
2-octyldodecyl (OD) =
Linear alkyl chains
Branched alkyl chains
(R 1 = C10, R 2 = HD)
(R 1 = C10, R 2 = OD)
(R 1 = C12, R 2 = HD)
(R 1 = C12, R 2 = OD)
(R 1 = C14, R 2 = HD)
(R 1 = C14, R 2 = OD)
PTzBT-EHHD
PTzBT-EHOD
PTzBT-BOBO
PTzBT-BOHD
PTzBT-BOOD
(R 1 = EH, R 2 = HD)
(R 1 = EH, R 2 = OD)
(R 1 = BO, R 2 = BO)
(R 1 = BO, R 2 = HD)
(R 1 = BO, R 2 = OD)
R 1 : linear, R 2 : branched
R 1 , R 2 : branched
C 6
C 8
C 10
C 12
C 10
C 12
C 14
Fig. 5.6 Chemical structures of PTzBTs with different side chain compositions. Reproduced with
permission [25]. Copyright (2014) Wiley
The polymers afforded several different textures in the 2D GIXD image that are
characteristics of certain orientational motifs depending on the side chain composition (Fig. 5.7). PTzBT-14HD (R
1
= C14 and R
2
= HD) exhibited a texture corresponding to a predominant edge-on orientation as also shown in Fig. 5.5b. When R
1
was shorter such as C12 and C10 (PTzBT-12HD, -10HD), the diffraction texture,
in particular, for π–π stacking structure, became bimodal and face-on, respectively.
Similar change in the texture was also observed when the longer branched side chain
(OD) was used as R
2 (PTzBT-10OD, -12OD, and -14OD). PTzBT-14OD gave the
texture similar to that of PTzBT-12HD, where both the polymers have the length
difference of two carbons between R
1 and R
2 . By shortening the linear side chain,
PTzBT-12OD and 10OD, the face-on fraction became more dominant. These results
suggest that PTzBTs can form the face-on orientation when the size of the branched
side chain is larger. In addition, as PTzBT-10HD and -12OD showed strong diffractions corresponding to the face-on orientation, introduction of the linear and branched
side chains with the same length could be a key to direct the backbone more face-on
with higher crystallinity at the same time.
When the linear side chain (R
1 ) of PTzBT-14HD was replaced with the branched
EH or BO group (PTzBT-EHHD or -BOHD), the polymers exhibited the texture
corresponding to the face-on orientation. In particular, in PTzBT-BOHD, where the
I. Osaka
S
N
S
S
N
S
R 1
R 1
S
N
S
S
N
S
R 2
R 2
n
PTzBT-10HD
PTzBT-10OD
PTzBT-12HD
PTzBT-12OD
PTzBT-14HD
PTzBT-14OD
Alkyl side chains used in this study:
n-decyl (C10) =
n-dodecyl (C12) =
n-tetradecyl (C14) =
2-ethylhexyl (EH) =
2-butyloctyl (BO) =
2-hexyldecyl (HD) =
2-octyldodecyl (OD) =
Linear alkyl chains
Branched alkyl chains
(R 1 = C10, R 2 = HD)
(R 1 = C10, R 2 = OD)
(R 1 = C12, R 2 = HD)
(R 1 = C12, R 2 = OD)
(R 1 = C14, R 2 = HD)
(R 1 = C14, R 2 = OD)
PTzBT-EHHD
PTzBT-EHOD
PTzBT-BOBO
PTzBT-BOHD
PTzBT-BOOD
(R 1 = EH, R 2 = HD)
(R 1 = EH, R 2 = OD)
(R 1 = BO, R 2 = BO)
(R 1 = BO, R 2 = HD)
(R 1 = BO, R 2 = OD)
R 1 : linear, R 2 : branched
R 1 , R 2 : branched
C 6
C 8
C 10
C 12
C 10
C 12
C 14
Fig. 5.6 Chemical structures of PTzBTs with different side chain compositions. Reproduced with
permission [25]. Copyright (2014) Wiley
The polymers afforded several different textures in the 2D GIXD image that are
characteristics of certain orientational motifs depending on the side chain composition (Fig. 5.7). PTzBT-14HD (R
1
= C14 and R
2
= HD) exhibited a texture corresponding to a predominant edge-on orientation as also shown in Fig. 5.5b. When R
1
was shorter such as C12 and C10 (PTzBT-12HD, -10HD), the diffraction texture,
in particular, for π–π stacking structure, became bimodal and face-on, respectively.
Similar change in the texture was also observed when the longer branched side chain
(OD) was used as R
2 (PTzBT-10OD, -12OD, and -14OD). PTzBT-14OD gave the
texture similar to that of PTzBT-12HD, where both the polymers have the length
difference of two carbons between R
1 and R
2 . By shortening the linear side chain,
PTzBT-12OD and 10OD, the face-on fraction became more dominant. These results
suggest that PTzBTs can form the face-on orientation when the size of the branched
side chain is larger. In addition, as PTzBT-10HD and -12OD showed strong diffractions corresponding to the face-on orientation, introduction of the linear and branched
side chains with the same length could be a key to direct the backbone more face-on
with higher crystallinity at the same time.
When the linear side chain (R
1 ) of PTzBT-14HD was replaced with the branched
EH or BO group (PTzBT-EHHD or -BOHD), the polymers exhibited the texture
corresponding to the face-on orientation. In particular, in PTzBT-BOHD, where the