Macromolecules, Vol. 35, No. 14, 2002
Hyperbranched Aromatic Polyimides 5379
9H). 13C NMR (δ, ppm): 167.7; 167.6; 166.9; 166.7; 158.7;
158.3; 157.6; 157.5; 135.9; 135.5; 131.8; 131.0; 126.2; 125.7;
120.0; 119.5; 117.9; 117.2; 107.6; 107.5; 52.5; 52.4. IR (KBr,
cm-1): 3300, 2951, 1728, 1593, 1578, 1496, 1456, 1439, 1290,
nonideal A2 + B3 polymerization approach (method B)
are suitable for smooth, flexible, and self-standing film
preparation.
1215, 1124, 1066, 1010, 846, 789. Anal. Calcd for C33H24O15
C, 60.00; H, 3.66. Found: C, 60.16; H, 3.69.
:
Exp er im en ta l Section
Ma ter ia ls. N-Methyl-2-pyrrolidinone (NMP), N,N-dimethyl-
formamide (DMF) and N,N-dimethylacetamide (DMAc) were
purified by vacuum distillation over calcium hydride. Pyridine
and triethylamine were purified by distillation over calcium
hydride. 1,4-Phenylenediamine was purified by sublimation
under vacuum before use. Diphenyl (2,3-dihydro-2-thioxo-3-
benzoxazolyl)phosphonate (DBOP) is a regent grade product
of Tokyo Chemical Industry Co., Ltd., and was used as
received. All other chemicals are regent grade and were used
as received unless otherwise stated.
Mon om er P r ep a r a tion . Syn th esis of 1,3,5-Tr i(3, 4-d i-
cya n op h en oxy)ben zen e (1). To a completely dry flask, 1.26
g (0.01 mol) of 1,3,5-benzenetriol and 5.19 g (0.03 mol) of
4-nitrophthalonitrile were dissolved in 60 mL of DMF. Then
8.28 g (0.06 mol) of potassium carbonate was added into the
flask, and the mixture was stirred at room temperature for
48 h. The reaction mixture was poured into 1000 mL of water.
The crude product was collected by filtration, washed with
water, and dried under vacuum. After refluxing in methanol
twice, the product was filtrated and washed using cold
methanol for three times. The white powdery product was
dried under vacuum, affording 4.08 g of 1,3,5-tri(3, 4-dicyano-
phenoxy)benzene (1). Yield: 76%. 1H NMR (δ, ppm): 8.15-
8.12 (d, 3H); 7.97-7.96 (d, 3H); 7.65-7.61(q, 3H); 7.05 (s, 3H).
13C NMR (δ, ppm): 160.1; 159.6; 136.1; 123.0; 122.9; 116.7;
115.3; 115.2; 109.5; 108.9. IR (KBr, cm-1): 2230, 1621, 1586,
1566, 1487, 1454, 1413, 1306, 1280, 1249, 1196, 1170, 1135,
1121, 1088, 1007, 951, 898, 849, 526. Anal. Calcd for
Mod el Com p ou n d P r ep a r a tion . Syn th esis of Den d r itic
Mod el Com p ou n d . In a dry flask purged with nitrogen, 0.137
g of 3 and 0.078 g of p-toluidine were dissolved in 2 mL of dry
DMAc. The reaction solution was stirred for 3 h, and then 0.22
mL of pyridine and 0.35 mL of acetic anhydride were added.
The temperature was elevated to 115 °C and kept there
overnight. After cooling to room temperature, the reaction
mixture was poured into a large amount of water to precipitate
the product. After filtration, the precipitate was washed with
100 mL of methanol for three times and dried under vacuum.
Yield: 96%. 1H NMR (δ, ppm): 7.98 (d, 3H); 7.65-7.59 (t, 6H);
7.29-7.28 (d, 12H); 6.86 (s, 3H). 13C NMR (δ, ppm): 161.2,
157.8, 137.5, 129.2, 129.1, 126.9, 126.3, 125.6, 123.9, 113.1,
113.0, 107.1, 20.6. IR (KBr, cm-1): 1776, 1724, 1599, 1516,
1479, 1450, 1441, 1375, 1267, 1236, 1197, 1165, 1120, 1091,
1003, 858, 819, 792, 779, 746, 696, 671. Anal. Calcd for
C
51H33O9N3: C, 73.64; H, 4.00; N, 5.05. Found: C, 73.36; H,
4.23; N, 5.11.
Syn th esis of Ter m in a l Mod el Com p ou n d . The terminal
model was prepared by a multistep synthesis (eq 4) and will
be published elsewhere. 1H NMR (δ, ppm): 8.18-8.13 (m, 2H);
7.86-7.78 (m, 3H); 7.59-7.57 (m, 2H); 7.48-7.35 (m, 6H);
6.72-6.69 (t, 3H). 13C NMR (δ, ppm): 168.6, 168.1, 167.4,
166.0, 162.6, 161.6, 157.8, 157.2, 156.3, 146.1, 137.6, 136.4,
134.2, 131.4, 127.8, 127.5, 126.3, 125.7, 124.1, 119.9, 117.7,
114.1, 113.3, 110.6, 110.3, 100.0. IR (KBr, cm-1): 3086, 1851,
1782, 1724, 1597, 1523, 1498, 1481, 1456, 1444, 1371, 1346,
1267, 1199, 1120, 1076, 1001, 933, 889, 852, 837, 752, 740.
P olym er P r ep a r a tion . Meth od A. Syn th esis of 4-Tolu i-
d in e En d -Ca p p ed P oly(a m ic a cid ) (TE-P AA). To a solution
of 0.253 g of tri(phthalic anhydride)(3) in 10 mL of dry DMAc
was added a solution of 0.048 g of 1,4-phenylenediamine in
7.5 mL of DMAc dropwise within 30 min. The reaction
temperature was kept at 0 °C. After the addition, the reaction
mixture was stirred for 2 h at room temperature, and then,
0.048 g of p-toluidine was added. The reaction was allowed to
continue for additional 6 h. The resulting clear solution was
poured into methanol containing 1% LiCl to precipitate the
product. After being washed with methanol several times, the
product was dried at room temperature under reduced pres-
sure. A pale-yellow powdery TE-P AA was obtained. Yield:
95%. 1H NMR (δ, ppm): 9.97-9.91 (d, 1H); 7.92-7.90 (d, 1.1H);
7.57-7.50 (d, 4.6H); 7.34-7.30 (m, 1.3H); 7.22-7.19 (d, 1.8H);
7.11-7.08 (d, 1.1H); 6.70-6.51 (m, 2.3H); 2.26 (s, 1.8H). IR
(KBr, cm-1): 3600-2000, 1776, 1720, 1595, 1516, 1479, 1454,
1408, 1375, 1321, 1263, 1207, 1118, 1007, 949, 891, 835, 796,
748, 698 524. ηinh ) 0.28 dL/g.
C
30H12O3N6: C, 71.43; H, 2.40; N, 16.66. Found: C, 71.23; H,
2.79; N, 16.66.
Syn th esis of 1,3,5-Tr i(3, 4-d ica r boxylp h en oxy)ben zen e
(2). In a 200 mL flask, 6.56 g (0.013 mol) of (1) and 13.83 g
(0.25 mol) of potassium hydroxide were dissolved in 120 mL
of water/ethylene glycol (1:1 volume) mixed solvent. The
mixture was refluxed for 4 h until the evolution of byproduct
ammonia was ceased. The yellow clear solution was poured
into 300 mL of water and the pH of solution was adjusted to
be 3-4. The white precipitate was collected by filtration and
washed with dilute hydrochloric acid and then water. After
recrystallization from aqueous acetic acid, 8.0 g of 1,3,5-tri(3,
4-dicarboxylphenoxy)benzene (2) was obtained as a white
crystal. Yield: 90%. 1H NMR (δ, ppm): 8.02-7.99 (d, 3H); 7.56
(s, 3H); 7.22-7.19(q, 3H); 6.66 (s, 3H). 13C NMR (δ, ppm):
167.4; 167.1; 157.8; 157.5; 146.6; 143.2; 138.3; 137.2; 119.5;
106.2. IR (KBr, cm-1): 3600-2250, 1717, 1593, 1578, 1496,
1456, 1417, 1377, 1266, 1221,1120, 1065, 1008, 898, 880, 845,
793, 775, 656. Anal. Calcd for C30H18O15: C, 58.26; H, 2.90.
Found: C, 58.02; H, 2.98.
Syn th esis of An h ydr ide Ter m in ated P olyim ide (ATP I).
To a solution of 0.253 g of tri(phthalic anhydride) (3) in 10
mL of dry DMAc was added dropwise a solution of 0.048 g of
1,4-phenylenediamine in 7.5 mL of DMAc within 30 min at 0
°C. After the addition, the reaction mixture was stirred for 2
h at room temperature. Then 6 mL of acetic anhydride and 4
mL of pyridine were added to the reaction mixture, and the
solution was stirred at room temperature for additional 5 h.
Then the reaction temperature was elevated to 115 °C and
kept overnight. After precipitation in dry toluene, the product
was collected by filtration and dried under vacuum. Yield:
Syn th esis of 1,3,5-Tr i(1,3-d ioxo-1,3-d ih yd r oisoben zo-
fu r a n -5-yloxy) ben zen e (3). In a 50 mL flask, 0.5 g of (2)
was dissolved in 2 mL of acetic anhydride and 20 mL of acetic
acid. The solution was kept at reflux for 1 h under nitrogen,
and a white crystal was formed. The crystal was isolated by
filtration to give 0.42 g of 1,3,5-tri(1,3-dioxo- 1,3-dihydroisoben-
1
zofuran-5-yloxy)benzene (3). Yield: 92.0%. H NMR (δ, ppm):
8.10-8.07 (d, 3H); 7.79 (s, 3H); 7.72-7.69 (d, 3H); 6.96 (s, 3H).
13C NMR (δ, ppm): 162.6; 162.4; 157.2; 157.1; 134.0; 127.7;
125.7; 114.1; 108.5; 107.8. IR (KBr, cm-1): 1848, 1773, 1597,
1482, 1464, 1445, 1349, 1276, 1217, 1166, 1122, 1077, 1007,
932, 890, 849, 739, 670. Anal. Calcd for C30H12O12: C, 63.84;
H, 2.14; N. Found: C, 63.60; H, 2.27.
1
97%. H NMR (δ, ppm): 7.96-7.95 (m, 1.7H); 7.58-7.22 (m,
7.5H); 6.83-6.69 (t, 1H). IR (KBr, cm-1): 1853, 1780, 1720,
1593, 1516, 1477, 1437, 1358, 1261, 1236, 1192, 1118, 1074,
995, 887, 827, 787, 740, 690, 671, 628, 524.
Syn th esis of 1,3,5-Tr i[(3-m eth yloxyca r bon yl-4-ca r box-
yl)p h en oxy]ben zen e a n d Isom er s (4). To a 100 mL flask
was added 2.5 g of 3 and 50 mL of methanol. The mixture
was refluxed for 24 h, and the solid was completely dissolved
in the solution. The resulting solution was poured into ice-
water and the isomeric mixture (4) was collected as a white
Syn th esis of 4-Tolu id in e En d -Ca p p ed P olyim id e by
Ch em ica l Im id iza tion (TEP I). To a solution of 0.1 g of TE-
P AA in 20 mL of DMAc were added 3 mL of acetic anhydride
and 2 mL of pyridine. The solution was heated at 100 °C
overnight. After cooling to room temperature, the solution was
poured into methanol to precipitate the product. A yellow
powdery TEP I was collected and dried under vacuum. Yield:
1
powder. Yield: 92%. H NMR (δ, ppm): 7.79-7.76 (d, 2.2H);
7.67, 7.64 (d, 0.80H); 7.27-7.20 (m, 6H); 6.74 (s, 3H); 3.71 (s,