Journal of Polymer Science, Part A: Polymer Chemistry
Supporting Information
Synthesis and Characterization of High Nitrile Content Polyimides as Dielectric Films for Electrical
Energy Storage
David H. Wang,1,2 Brian A. Kurish,1,2 Imre Treufeld,3 Lei Zhu,3* and Loon-Seng Tan1,*
1
Materials & Manufacturing Directorate, Soft-Matter Materials Branch (AFRL/RXAS), Air Force Research
Laboratory, Wright-Patterson Air Force Base, Ohio 45433-7750
2
UES Inc., Dayton Ohio, 45432
3
Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland,
Ohio 44106
*Email Correspondence: Loon.Tan@us.af.mil (L.-S.T.); lxz121@case.edu (L.Z.)
Instrumentation. Gas chromatography/mass spectroscopy (GC/MS) was performed using a Varian 1200
Series instrument. Transmittance Infrared (IR) spectra were recorded on a Nicolet Nexus 470 F-T
spectrophotometer. Attenuated Total Reflection IR (ATR-IR) was measured on a Bruker Alpha-R
spectrometer. Proton and carbon nuclear magnetic resonance spectra were measured at 300 MHz on a
Bruker AVANCE 300 spectrometer.
Scheme SS-1. Attempted synthesis of 6a from of 2,6-dihydroxybenzonitrile (2) with 2-fluoro-6-(3aminophenoxy)benzonitrile (I).
Into a 250mL three-neck round-bottom flask equipped with stir bar, nitrogen inlet, and condenser were
charged 2-fluoro-6-(3-aminophenoxy)benzonitrile (4.56 g, 20.0 mmol), 2,6-dihydroxybenzonitrile (1.35 g,
10.0 mmol), potassium carbonate (3.76 g, 20.0 mmol) and N-methyl-2-pyrrolidinone (75 mL). The
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mixture was stirred at 100 °C for 48 h and progress was observed by GC/MS. The nucleophilic
substitution was very slow. The mixture turned green with time. There were several spots on TLC and
separation of product 6a from byproducts was unsuccessful.
Scheme SS-2. Attempted synthesis of 6b from of 2,6-bis(t-butyldimethylsilyloxy)benzonitrile (III) with 6(4-aminophenoxy)-2-fluorobenzonitrile (IV).
2,6-bis(t-butyldimethylsilyloxy)benzonitrile (II). Into a 250 mL three-neck round-bottom flask equipped
with stir bar and nitrogen inlet was charged 2,6-dihydroxybenzonitrile (2.27 g, 17.0 mmol), tbutyldimethylsilyl chloride (5.56 g, 37.0 mmol), imidazole (2.52 g, 37.0 mmol) and methylene chloride
(100 mL). The reaction mixture was stirred at room temperature for 24 h and the white precipitate was
filtered through Celite. The filtrate was dried by rotavapor followed by vacuum-oven drying at 50 °C to
afford 5.39 g (88.2%) of white crystals. m.p. 70.5-74.7 °C. 1H-NMR (CDCl3): 0.27 (s, 12H, CH3), 1.04 (s,
18H, C(CH3)3), 6.46-6.48 (d, 2H, Ar-H), 7.21-7.26 (t, 1H, Ar-H).
Attempted synthesis of 6a from of 2,6-bis(t-butyldimethylsilyloxy)benzonitrile (III) with 6-(4aminophenoxy) -2-fluorobenzonitrile (IV).
Method 1. Into a three-neck round-bottom 100 mL flask equipped with stir bar, condenser, and
nitrogen inlet were charged potassium carbonate (1.66 g, 12.0 mmol), 2,6-bis(t-
2
butyldimethylsilyloxy)benzonitrile (1.82 g, 5.0mmol), 6-(4-aminophenoxy)-2-fluorobenzonitrile (2.28 g,
10.0 mmol) and 30 mL N-methyl-1-pyrrolidinone. The reaction was brought to 100 °C and stirred for 48
h. GC/MS spectra were taken during the reaction which indicated hydrolysis of II.
Method 2. Into a three-neck round-bottom 250 mL flask equipped with stir bar and nitrogen inlet was
charged 2,6-bis(t-butyldimethylsilyloxy)benzonitrile (1.82 g, 5.0 mmol), 6-(4-aminophenoxy)-2fluorobenzonitrile (2.28 g, 10.0 mmol), cesium fluoride (30 mg) and diphenylsulfone (5.0 g). The flask
was lowered into a preheated 240 °C oil bath. Once the solid completely dissolved the mixture was
stirred for an additional 6 min. II started to evaporate at 240 °C. No reaction occurred according to
GC/MS spectra.
Scheme SS-3. Attempted synthesis of 6b from of 2,6-bis(2-cyano-3-chlorophenoxy)benzonitrile (IV) with
4-aminophenol (5a).
2,6-Bis(2-cyano-3-chlorophenoxy)benzonitrile (VI). Into a 50 mL three-neck round-bottom flask
equipped with stir bar and nitrogen inlet was charged 1.35 g 2,6-dihydroxybenzonitrile (1.35 g, 10.0
mmol), 2-chloro-6-fluorobenzonitrile (3.11 g, 20.0mmol), K2CO3 (3.32 g, 24.0 mmol) and DMAc (20 mL).
Reaction temperature was raised to 100 °C for 60 h. The mixture was allowed to cool to room
temperature and filtered. The filtrate was poured into approximately 200 mL H2O to precipitate the
product. Then product was collected by filtration and washed with water. It was dried overnight at 80
C to yield 2.81 g (69.2%) of white powder. m.p. 219.0-220.1 C. 1H-NMR: 7.17-7.19 (d, 2H, Ar-H), 7.317.34 (dd, 2H, Ar-H), 7.63-7.65 (dd, 2H, Ar-H), 7.76-7.80 (t, 3H, Ar-H). Elemental analysis: Calcd: C,
62.09%; H, 2.23%; N, 10.34%. Found: C, 61.86%; H, 2.35%; N, 10.03%. 13C-NMR (DMSO-d6): 77.12,
112.56, 117.69, 126.13, 136.22, 136.79, 136.86, 139.26, 157.65, 157.98.
Attempted synthesis of 6b from of 2,6-Bis(2-cyano-3-chlorophenoxy)benzonitrile (IV) with 4aminophenol (5a). Into a 100 mL three-neck round-bottom flask equipped with stir bar, condenser, and
nitrogen inlet were charged 2,6-bis(2-cyano-3-chlorophenoxy)benzonitrile (1.00 g, 2.46 mmol) and 20
mL of NMP. Once the solid was dissolved, 4-aminophenol (0.59 g, 5.42 mmol) and K2CO3 (0.82, 5.91
mmol) were added and temperature was raised to 120 °C for 48 h. The mixture was allowed to cool to
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room temperature and filtered. The filtrate was precipitated into 125 mL of water. The solid was
collected by filtration and dried overnight at 80 °C. NMR spectrum showed impurities, and only 0.5 g
was collected. So, 5 g NaCl was added into the filtrate and the mixture was extracted with EtOAc twice.
Organic layers were combined and washed twice with water. Solvent was then removed and dried in
vacuum oven at 80 °C. A sticky, viscous goo remained, likely due to NMP remaining, so it was refluxed in
100 mL EtOH to afford little solid. The EtOH filtrate was a black color. TLC was performed on the initial
aqueous solution and the EtOH solution, and the aqueous solution clearly had no product.
Figure SS-1. 1H-NMR spectra of polyimides: (a) p,p-3BCN -6FDA (b) m,m-3BCN-OPDA both in DMSO-d6.
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Figure SS-2.
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C-NMR spectra of polyimides: (a) p,p-3BCN -6FDA (b) m,m-3BCN-OPDA both in DMSO-d6.
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Figure SS-3. ATR-IR spectra of m,m-3BCN -BTDA polyimides: (a) prepared by thermal imidization; (b)
prepared by chemical imidization.
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