NEW NANOSTRUCTURED POLY(AMIDE-IMIDE)S
237
TABLE 1
is reproducible. It also can be carried out at lager scales. For
the purification of the polymer and removal of any unreacted
monomers, it was dissolved in minimum amount of DMF. The
obtained solution was stirred for 4 h. Then it was poured in
15 mL of methanol and stirred for another 1 h. The resulted
solid was washed with 15 mL of methanol and 15 mL of hot
water. The other PAIs, PAI8b-PAI8d were prepared and purified
by a similar procedure.
Synthesis and some physical properties of PAI8a–PAI8d
prepared in molten TBAB under classical heating method
b
25
Yield
(%)
ηinh
[α]
Na,589
Diacid
Polymera
(dL/g)
(◦)b
Color
7a
7b
7c
7d
PAI8a
PAI8b
PAI8c
PAI8d
91
88
90
85
0.38
0.32
0.28
0.34
−24.18
−22.26
−30.20
−28.82
Brown
Brown
Brown
Brown
For PAI8a, FT-IR Peaks (KBr): 3384 (w), 2925 (w), 1776
(m), 1719 (s), 1671 (m), 1602 (m), 1546 (s), 1450 (s), 1376 (s),
1069 (m), 725 (m), 619 (m) cm–1.
aPolymers were precipitated in methanol.
bMeasured at a concentration of 0.5 g/dL in DMF at 25◦C.
1H NMR (400 MHz, DMSO-d6): 0.99–1.01 (d, 6H, J = 8 Hz),
2.55–2.90 (m, 1H), 4.64–4.66 (d, 1H, distorted), 7.28 (s, 1H, Ar-
H), 7.54 (s, 1H, Ar-H), 7.96 (s, 1H, Ar-H), 8.34–8.38 (d, 2H,
Ar-H, distorted), 8.48–8.50 (d, 2H, Ar-H, distorted), 8.65 (s,
1H, Ar-H), 10.31 (s, 1H), 10.92 (s, 1H), 12.73 (s, 1H) ppm.
For PAI8b, FT-IR Peaks (KBr): 3312 (w), 2957 (w), 1777
(m), 1718 (s), 1672 (m), 1602 (m), 1546 (s), 1450 (m), 1322 (s),
1009 (w), 875 (m), 754 (m), 691 (m) cm–1.
methionine, and L-isoleucine) in refluxing acetic acid, as shown
in Scheme 2.[31]
Polymer Synthesis
In this work, a series of novel optically active and nanostruc-
tured PAIs (8a–8d) were synthesized by the direct polyconden-
sation reaction of diacids 7a–7d with diamine 4 in molten TBAB
as a reaction medium and TPP as activating agent (Scheme 2).
The synthesis and some physical properties of these novel opti-
cally active PAIs are listed in Table 1. The inherent viscosities
of the resulting polymers under optimized condensations were
in the range of 0.28–0.38 dL/g and the yields were 85–91%. All
of PAIs are optically active and show different optical rotations
because various factors effects on the specific rotation such as
the structure of monomer and catalyst.
1H NMR (400 MHz, DMSO-d6): 0.92–0.94 (d, 6H, J =
7.2 Hz), 1.38–1.58 (m, 1H), 2.04–2.06 (dd, 2H, distorted),
5.02–5.04 (t, 1H, distorted), 7.25 (s, 1H, Ar-H), 7.55 (s, 1H, Ar-
H), 7.98 (s, 1H, Ar-H), 8.13–8.17 (d, 2H, distorted), 8.19–8.26
(d, 2H, Ar-H, distorted), 8.61 (s, 1H, Ar-H), 10.25 (s, 1H), 10.91
(s, 1H), 12.72 (s, 1H) ppm.
For PAI8c, FT-IR Peaks (KBr): 3303 (w), 2964 (w), 1777
(m), 1719 (s), 1676 (m), 1602 (s), 1541 (s), 1451 (s), 1321 (m),
1086 (m), 862 (m), 724 (m) cm–1.
For PAI8d, FT-IR Peaks (KBr): 3345 (w), 2961 (w), 1766
(m), 1719 (s), 1655 (m), 1600 (s), 1542 (s), 1486 (m), 1375 (s),
1070 (m), 812 (m), 724 (m), 630 (m) cm–1.
Characterization of PAIs
1
The resulting PAIs were characterized by FT-IR, H NMR
spectroscopy, and elemental analysis technique. The FT-IR
spectra of all PAIs showed absorptions of amide N-H bonds
appeared around 3304–3384 cm−1. The peaks at 1776 cm–1
and 1719 cm–1 are commonly attributed to the asymmetric and
symmetric stretches of carbonyl groups in the imide ring and
RESULTS AND DISCUSSION
Synthesis of Monomers
3,5-diamino-N-(thiazol-2-yl)benzamide (4) was synthesized 1676 cm−1 C=O is stretching vibration for amide group and
by using a two-step reaction that is shown in Scheme 1.[30]
1321 cm–1 C–N stretching vibration. The FT-IR spectrum of
Chiral diacid monomers 7a–7d were prepared by the con- PAI8a is shown in Figure 1.
densation reaction of one equimolar of TMA and one equimo-
The structure of obtained polymers was also confirmed by
1
lar of different natural amino acids (S-valine, L-leucine, L- 1H NMR spectroscopy. The H NMR spectrum (400 MHz) of
SCH. 1. Synthesis of diamine monomer. (color figure available online).