436
Received: 18 March 2010 Revised: 4 July 2010 Accepted: 11 August 2010 Published online in Wiley Online Library: 10 November 2010
(wileyonlinelibrary.com) DOI 10.1002/pi.2966
Synthesis and characterization of a novel
siloxane-imide-containing polybenzoxazine
Kai-Chi Chen,
a,b
Hsun-Tien Li,
b
Wen-Bin Chen,
b
Chun-Hsiung Liao,
b
Kien-Wen Sun
a
and Feng-Chih Chang
a
∗
Abstract
A novel siloxane-imide-containing polybenzoxazine based on N,N-bis(N-phenyl-3,4-dihydro-2H-benzo[1,3]oxazine)-5, 5-bis(1,1,3,3-tetramethyldisiloxane-1,3-diyl)-bis(norborane-2,3-dicarboximide) (BZ-A1) was successfully synthesized. The thermal properties of BZ-A1 are superior to those of conventional polybenzoxazines lacking siloxane groups. Polymerized BZ-A1 possesses extremely low surface free energy (γs = 15.1 mJ m−2) after curing at 230◦C for 1 h. Moreover, the surface free energy of polymerized BZ-A1 is more stable than conventional bisphenol A-type polybenzoxazine during thermal curing and annealing processes, indicating that polymerized BZ-A1 is more suitable for applications requiring low surface free energy materials for high temperatures over long periods of time.
c
2010 Society of Chemical Industry
Keywords: polybenzoxazine; benzoxazine; siloxane; surface free energy; thermal stability; BZ-A1
INTRODUCTION
The diverse applications of thermosetting polymers have attracted much interest.1 – 4 Polybenzoxazines (PBZs) are some of these materials that have attracted great interest from both academia and industry because of their superior properties.5 – 8Benzoxazine monomers, formed from amines and phenol in the presence of formaldehyde, were first synthesized by Holly and Cope.9 Later, a bifunctional benzoxazine precursor was synthesized by Ning and Ishida5 and the resulting polymers possessed high mechanical integrity. Benzoxazine monomers can be prepared readily from inexpensive raw materials.10 – 13PBZs possess unique properties such as low water absorption (despite the large number of OH groups present in the backbone structure),12,13 high moduli,14 excellent resistance to chemicals,15 near-zero volumetric shrinkage/expansion upon polymerization16and high glass transition temperatures (Tg).17
In our previous study, a new class of PBZ was developed which exhibited extremely low surface free energies – even lower than that of pure Teflon – through strong intramolecular hydrogen bonding.18 – 21 Furthermore, we applied the low surface free energy PBZ material as an efficient mold-release agent for silicon molds22and a stable superhydrophobic surface.19Typically, the surface free energy of the PBZ system decreases initially and then increases steadily upon increasing the curing time, indicating that the surface free energy of PBZs is not stable during curing and annealing processes.
In order to overcome this problem, we designed a siloxane segment into benzoxazine to improve the stability of surface free energy during high-temperature storage.23 However, Liu et al.24 found that the addition of soft segments of bis-propyltetramethyldisiloxane in benzoxazines usually results in lower Tg and poorer thermal properties. Ardhyananta
et al.25 developed a polymerized bifunctional bisphenol A-type
benzoxazine (PBa)–polydimethylsiloxane (PDMS) hybrid system using the sol–gel process to increase Tg to above 200◦C. Poly(imide-siloxane) selected to blend into PBa to increase Tg was also discussed by Takeichi et al.26 An imide-containing structure incorporated into benzoxazine can improve the thermal properties of PBZs.23In the study reported here, we formulated a benzoxazine containing a siloxane-imide segment: N,N -bis(N-phenyl-3,4-dihydro-2H-benzo[1,3]oxazine)-5,5-bis(1,1,3,3 -tetramethyldisiloxane-1,3-diyl)-bis(norborane-2,3-dicarboximide) (BZ-A1). It possesses a relatively low surface free energy and better thermal properties than those PBZs lacking siloxane groups after thermal crosslinking. Furthermore, the surface free energy of the polymerized BZ-A1 is more stable during high-temperature thermal curing processes.
EXPERIMENTAL
Materials
1,4-Dioxane and paraformaldehyde (95%) were purchased from TEDIA (USA) and Showa Chemicals (Japan), respectively. Ethyl acetate (99.9%) was used as received from Mallinckrodt Inc. (USA). Aniline (99%), ethylene glycol (≥99%) and diiodomethane (99%) were obtained from Aldrich (USA). Bifunctional bisphenol A-type benzoxazine (Ba; Fig. 1) was purchased from Shikoku Chemicals (Japan).
∗ Correspondence to: Feng-Chih Chang, Institute of Applied Chemistry, National Chiao-Tung University, Hsin-Chu, Taiwan. E-mail: [email protected]
a Institute of Applied Chemistry, National Chiao-Tung University, Hsin-Chu,
Taiwan
b Material and Chemical Research Laboratories, Industrial Technology Research
437
CH3 CH3 N O N OFigure 1. Structure of the bifunctional bisphenol A-type benzoxazine Ba.
Synthesis of siloxane-containing dihydroxyl compound Siloxane-imide-containing dianhydride (A1) and siloxane-containing dihydroxyl compound (A1-OH) were synthesized ac-cording to the method reported by Li et al.27(Scheme 1). A light brown powder, A1-OH, was obtained in 88% yield. The chemical structure of A1-OH was confirmed from1H NMR and Fourier trans-form infrared (FTIR) spectral analyses.1H NMR (CDCl3; δ, ppm): 0.01–0.02 (m, 12H), 0.61 (m, 2H), 1.54–1.62 (m, 8H), 2.74 (m, 2H), 2.78 (m, 2H), 3.12–3.17 (m, 4H), 6.70–6.73 (d, 4H), 6.90–6.94 (d, 4H), 7.42 (s, 2H). FTIR: 1789 and 1720 cm−1(imide), 3100–3500 cm−1 (OH).
Synthesis of BZ-A1
Aniline (1.88 g, 0.02 mol) was added dropwise into a mixture of A1-OH (6.44 g, 0.01 mol), paraformaldehyde (1.26 g, 0.04 mol) and 1,4-dioxane (100 mL) in a 250 mL round-bottom flask equipped with a magnetic stirrer bar. The mixture was then heated under reflux at 115◦C for 20 h, and it gradually became homogeneous, turning dark brown. The resulting mixture was filtered and the solvent was evaporated under vacuum. The residue was dissolved in ethyl acetate and washed five times sequentially with 1 N aqueous NaOH and distilled water. Evaporation of the solvent and vacuum drying in an oven provided BZ-A1 as a brown powder (73.0% yield).
Contact angle measurements
The surface free energy of polymer samples was determined through contact angle goniometry at 25◦C using a Kr ¨uss GH-100 goniometer interfaced with image-capture software. Deionized water, ethylene glycol and diiodomethane were used as standards. To obtain reliable contact angle data, at least three droplets (5µL each) were dispensed at different regions of the same piece of film; at least two pieces of film were used. Thus, at least six advancing contact angles were averaged for each type of film and each type of liquid.
Preparation of PBZ films
An aliquot (1 mL) of benzoxazine monomer (BZ-A1 or Ba; 0.5 g) solution in tetrahydrofuran (THF; 10 mL) was filtered at room
O O O Si O Si O O O Si Si CH3 CH3 CH3 CH3 H H O O O + 2 Pt Toluene, 80°C A1 CH3 CH3 O CH3 CH3 HO N O O Si O Si N O O OH O O O Si O Si O O CH3 CH3 O CH3 CH3 OH H2N + 2 Benzene/ dimethylformamide -2H2O CH3 CH3 CH3 CH3 A1-OH A1-OH NH2 O N O O Si O Si N O O N O N CH3 CH3 CH3 CH3 1 2 4 + + 1,4-dioxane reflux/ 20hrs BZ-A1 N HO Si O Si CH3 CH3 CH3 CH3 N O O O O OH HCHO -2H2O
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Table 1. Curing conditions for PBZs
Ba BZ-A1 Curing conditions 200◦C for 2 h+ 230◦C
for 2 h 200◦C for 2 h+ 230◦C for 2 h 200◦C for 2 h+ 230◦C for 4 h 200◦C for 2 h+ 230◦C for 4 h 200◦C for 2 h+ 230◦C for 6 h 200◦C for 2 h+ 230◦C for 6 h
temperature through a 0.2µm syringe filter (poly(vinylidene flu-oride) membrane, Millipore Co.) and then spin-coated (1500 rpm, 45 s) onto a glass slide (100 mm× 100 mm × 1 mm). The sample was then cured in an oven at a desired temperature for a desired period of time.
Preparation of siloxane-imide-containing PBZ
Ba and BZ-A1 were subjected to the curing schedule listed in Table 1. After completing the curing process, samples were slowly cooled to room temperature. No catalyst was used in these experiments.
Characterization
FTIR spectra were recorded using a Nicolet Avatar 320 FTIR spectrophotometer. Samples were prepared by casting BZ-A1 monomer solutions directly onto a potassium bromide plate and evaporating the THF at 50◦C under vacuum. The spectrometer was operated in transmission mode utilizing 32 scans at a resolution of 2 cm−1.1H NMR spectra were recorded using a Varian UNITY Inova-400 NMR spectrometer operating at a proton frequency of 400 MHz and with CDCl3 as the solvent. Molecular weights were determined using a TRIO-2000 liquid chromatography/mass spectrometry (LC-MS) apparatus and a DB-5 MS column. DSC was performed using a TA Instruments DSC-Q10 apparatus operated at a heating rate of 10◦C min−1under a nitrogen atmosphere (gas flow rate of 40 mL min−1). Benzoxazine samples of approximately 5 mg were scanned in hermetic aluminium sample pans. TGA was performed using a TA Instruments TGA-Q500 apparatus operated at a heating rate of 20◦C min−1under an atmosphere of nitrogen or air. An energy-dispersive spectrometry (EDS) system was used for elemental testing, which was carried out using an LEO-1530 FE-SEM system.
RESULTS AND DISCUSSION
Synthesis of BZ-A1
BZ-A1 was prepared according to Scheme 1 and its chemical structure was confirmed using FTIR and1H NMR spectroscopies and LC-MS. The FTIR spectrum of BZ-A1 (Fig. 2) displays char-acteristic absorptions of a benzoxazine structure at 1498 and 1030 cm−1(vibrations of trisubstituted benzene ring), 1328 cm−1 (CH2 wagging of the oxazine unit) and 1230 cm−1 (asymmet-ric C–O–C stretching). The 1H NMR spectrum of BZ-A1 (Fig. 3) displays signals of aromatic protons at 6.60–7.40 ppm and charac-teristic peaks attributed to methylene units (oxazine Ar–CH2–N) at 5.30 and 4.60 ppm. LC-MS (Fig. 4) provides a molecular weight of 881.1 g mol−1, consistent with the calculated formula weight.
4000 3500 3000 2500 2000 1500 1000 500 1498cm-1 1328cm-1 O O O Si O Si N O O N O N CH3 CH3 CH3 CH3 v (cm-1) T (%) 1030cm-1 1230cm-1 N
Figure 2. FTIR spectrum of BZ-A1.
8 6 4 2 0 ppm a b c f h de g m benzene i, j,k l O N O O Si O Si N O O N O N CH3 CH3 CH3 CH3 a b c d e f m g h i j k l
Figure 3.1H NMR spectrum of BZ-A1.
Curing behavior of BZ-A1
Typically, benzoxazines undergo exothermic ring-opening reac-tions at ca 200–250◦C, which can be monitored using DSC. The reaction point of Ba is 228.7◦C; the energy of the exothermic ring-opening reaction is 296.0 J g−1(Fig. 5). The thermogram of BZ-A1 in Fig. 5 reveals a ring-opening exothermic reaction having an onset temperature at 194.9◦C and a peak point at 232.7◦C. The exothermic energy of BZ-A1 is 173.7 J g−1; i.e. it is lower than that of Ba, presumably due to the molecular weight effect, the molecular weight of BZ-A1 (879 g mol−1) being significantly higher than that of Ba (462 g mol−1). The polymerized forms of Ba (PBa) and BZ-A1 (PBZ-A1) were then cured in an oven under the curing conditions listed in Table 1.
Thermal stability of the poly(siloxane-co-imide)-containing benzoxazine PBZ-A1
PBZs usually exhibit good thermal properties after polymerization.28 T
g of PBZ-A1 after crosslinking is 186.1◦C (Fig. 6), which is substantially higher than that of typical PBZs (Tg of PBa is 150.0◦C).14 Liu et al24 have discussed that the longer and flexible of siloxane segments in the matrix structure results in lower of Tg(Tg from tan δ peak of siloxane copolybenzoxazine
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m/z 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 % 0 100 x15 2.01e6 108.12 266.08 299.31 401.97 406.37 714.67 568.27 881.09 O N O O Si O Si N O O N O N CH3 CH3 CH3 CH3Figure 4. LC-MS spectrum of BZ-A1.
228.69°C 208.74°C 296.0 J g–1 173.68°C 282.45°C 232.73°C 194.91°C 173.7 J g–1 173.68°C 286.71°C -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 Heat Flow (W g –1) 100 150 200 250 300 Temperature (°C) Ba BZ-A1
Exo Up Universal V4.4A
TA Instruments Figure 5. DSC thermograms of Ba and BZ-A1.
which named CP-F-Bz/BATMS-Bz-100 is 116 ◦C). Our PBZ-A1 structure features both siloxane and imide segments in the benzoxazine monomer where the imide segment tends to raise Tg. Bisphenol A is one of the phenolic compounds often used as the starting material for the synthesis of PBZs. PBa shows a high decomposition temperature (temperature of 5% weight loss is ca 300–330◦C) and high char yield (ca 30–42%) as obtained from TGA.28 – 32Liu et al.24found that the siloxane-containing PBZ CP-F-Bz/BATMS-Bz-100 has Td of 369◦C in air. Figure 7 shows TGA thermograms recorded in air; the results are summarized in Table 2. The 5 and 10% weight loss temperatures (T5 and T10, respectively) for PBZ-A1 cured at 200◦C for 2 h and 230◦C for 2 h are 380.1 and 441.1◦C, respectively, which are both higher than those of PBa or siloxane-containing PBZ. PBZ-A1 shows higher thermal stability than PBa because of the presence of the siloxane-imide-containing segment. Liu et al. used TGA to study a siloxane-containing PBZ, and they found that high thermal stability silica layers were formed during the thermal oxidation process and the layer structure protected the PBZ.33PBa–PDMS hybrids were investigated and it was found that introduction of PDMS into PBa results in the improvement of thermal stability of the hybrid.25
186.1 °C -0.60 -0.55 -0.50 -0.45 -0.40 -0.35 Heat Flow (W g –1 ) 100 120 140 160 180 200 220 Temperature (°C) Exo Up UniversalV4.4A TA Instruments Figure 6. Glass transition temperature of PBZ-A1, determined from the
DSC trace.
The better thermal stability of PBZ-A1 with higher decomposition temperature and high char arises from the siloxane and imide groups.
The presence of siloxane-imide groups improves the thermo-oxidative stability of benzoxazine by increasing the char yield to 10–12 wt% in air. This char yield is close to the inorganic content (Si–O–Si, 8.2%) in the BZ-A1 structure. EDS analysis was employed to analyze the elemental composition of the PBZ-A1 residue after TGA testing in air. Figure 8 shows an image of the residue from PBZ-A1 and its EDS trace. The silicon content in the residue is significantly higher than the carbon and oxygen contents, and so the residue from PBZ-A1 after TGA testing in air is primarily inorganic in nature. Thus, the siloxane units of BZ-A1 provide an inorganic content in its structure, therefore improving its thermal stability after crosslinking.
The same phenomena occur in the TGA thermograms recorded under a nitrogen atmosphere (Fig. 9; Table 3). T5 of PBa is ca 328–337◦C under nitrogen atmosphere, whereas that of PBZ-A1 is significantly higher (ca 355–362◦C). T5and T10of PBZ-A1 are both higher than those of PBa. PBZ-A1 also features a high
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-20 0 20 40 80 100 120 Weight (%) 0 200 400 600 800 1000 Temperature (°C) Ba - 200°C/2h+230°C/2h Ba - 200°C/2h+230°C/4h Ba - 200°C/2h+230°C/6h BZ-A1 - 200°C/2h+230°C/2h BZ-A1 - 200°C/2h+230°C/4h BZ-A1 - 200°C/2h+230°C/6h Universal V4.4A TA Instruments CH3 CH3 N O N O O N O O Si O Si N O O N O N CH 3 CH3 CH 3 CH3 BZ-A1 60 Ba O O BZ-A1Figure 7. TGA thermograms of PBa and PBZ-A1 (in air).
Table 2. Thermal stabilities of the cured PBZs PBa and PBZ-A1 (in air)
Polymer Curing conditions T5a(◦C) T10b(◦C) Tdc(◦C) Char yield at 850◦C (%)
Pba 200◦C for 2 h+ 230◦C for 2 h 337.3 365.5 349.3 0.2 200◦C for 2 h+ 230◦C for 4 h 347.0 376.8 346.4 −0.3 200◦C for 2 h+ 230◦C for 6 h 349.1 382.1 357.9 −0.1 PBZ-A1 200◦C for 2 h+ 230◦C for 2 h 380.1 441.1 472.2 10.1 200◦C for 2 h+ 230◦C for 4 h 389.4 444.2 480.7 11.3 200◦C for 2 h+ 230◦C for 6 h 392.0 449.3 478.1 12.0
aTemperature at which the weight loss is 5%. bTemperature at which the weight loss is 10%. cDecomposition temperature, onset point temperature.
0.0 0.5 1.0 1.5 2.0
Energy (keV) PBZ-A1/ after TGA test Si
O C
Figure 8. Residue and EDS analysis of PBZ-A1 after TGA.
weight residue after high-temperature decomposition. The char yield of PBZ-A1 after curing at 200◦C for 2 h and then 230◦C for 2 h is high (48%), i.e. it is increased by the presence of the siloxane-imide groups. It appears that PBZ-A1 has potential use as a flame-retardant material.
Surface behavior of PBZ-A1 and PBa
PBZs feature strong intramolecular hydrogen bonds resulting in extremely low surface free energies, even lower than that of pure Teflon.18Some of the intramolecular hydrogen bonds in as-cured samples tend to convert into intermolecular hydrogen bonds upon thermal treatment, thereby resulting in increased hydrophilicity and wettability. To broaden the applications of PBZs, benzoxazine monomers possessing less sensitivity towards thermal treatment are required.
The surface behaviors during the curing process of PBZ-A1 and PBa were characterized after spin-coating films with thicknesses of ca 150 nm. Table 4 lists the advancing contact angles and standard deviations for three different test liquids on the surfaces of PBa and PBZ-A1 films produced using various curing and annealing times. Due to the advancing contact angle being less sensitive to surface roughness and heterogeneity than the receding angle, advancing angle data are commonly used to calculate surface and interfacial tension components.34,35At a curing and annealing temperature of 230◦C, the contact angles for both PBa and PBZ-A1 for all test liquids increase initially during the first hour but decrease steadily thereafter (Fig. 10). For the PBa system, curing at 230◦C for 1 h results in the highest contact angles for all three test liquids: 106.1◦ for water, 82.5◦for ethylene glycol and 84.3◦for diiodomethane. For the PBZ-A1 system, similar trends are observed by curing and
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20 40 60 80 100 120 Weight (%) 0 200 400 600 800 1000 Temperature (°C) Ba - 200°C/2h+230°C/2h Ba - 200°C/2h+230°C/4h Ba - 200°C/2h+230°C/6h BZ-A1 - 200°C/2h+230°C/2h BZ-A1 - 200°C/2+230°C/4h BZ-A1 - 200°C/2+230°C/6h Universal V4.4A TA Instruments CH3 CH3 N O N O Ba O N O O Si O Si N O O N O N CH3 CH3 CH3 CH3 BZ-A1 Ba N CH3CH3Figure 9. TGA thermograms of Ba and BZ-A1 (under nitrogen).
Table 3. Thermal stabilities of the cured PBZs PBa and PBZ-A1 (under nitrogen)
Polymer Curing conditions T5a(◦C) T10b(◦C) Tdc(◦C) Char yield at 850◦C (%)
Pba 200◦C for 2 h+ 230◦C for 2 h 334.6 356.8 344.2 34.3 200◦C for 2 h+ 230◦C for 4 h 328.8 360.7 342.7 42.7 200◦C for 2 h+ 230◦C for 6 h 336.5 369.8 341.6 46.3 PBZ-A1 200◦C for 2 h+ 230◦C for 2 h 355.7 417.8 452.9 48.0 200◦C for 2 h+ 230◦C for 4 h 361.5 427.2 448.4 48.4 200◦C for 2 h+ 230◦C for 6 h 358.5 415.8 446.5 49.3
aTemperature at which the weight loss is 5%. bTemperature at which the weight loss is 10%. cDecomposition temperature, onset point temperature.
Table 4. Contact angles and surface free energies of the cured and annealed PBa and PBZ-A1 Curing conditions Contact angle (◦)
Surface free Polymer Temperature (◦C) Time (h) Water Ethylene glycol Diiodomethane energy, γs(mJ m−2)
Pba 230 0.5 105.9 82.1 83.4 17.0 1 106.1 82.5 84.3 16.6 2 93.9 70.0 76.3 22.5 4 78.8 55.6 68.6 30.0 8 59.4 25.5 53.8 43.6 24 13.7 20.3 45.8 42.6 PBZ-A1 230 0.5 106.7 83.2 79.5 18.5 1 108.8 85.4 86.8 15.1 2 108.0 83.5 83.6 16.6 4 106.5 82.5 83.1 17.0 8 99.4 74.7 78.2 20.4 24 84.0 69.3 71.5 24.6
annealing at 230◦C, except that the contact angles are all higher than those for the PBa system. Curing at 230◦C for 1 h also provides the highest contact angles for all three of the test liquids: 108.8◦ for water, 85.4◦for ethylene glycol and 86.8◦for diiodomethane. The contact angle for water on PBa is initially 105.9◦but decreases
markedly to 13.7◦ after curing for 24 h. In contrast, the contact angle for water on PBZ-A1 is initially 106.7◦, reaching 108.8◦after curing for 1 h and decreasing very slowly to 84.0◦ after curing for 24 h. Indeed, the contact angles for water on PBZ-A1 are all higher than those on PBa for all curing times, suggesting that the
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0 5 10 15 20 25 0 20 40 60 80 100 120Contact angle (deg)
Curing time (h) BZ-A1 - H2O BZ-A1 - EG BZ-A1 - DIM Ba - H2O Ba - EG Ba - DIM
Figure 10. Contact angles of PBZs after various curing times (EG, ethylene
glycol; DIM, diiodomethane).
0 5 10 15 20 25 0 10 20 30 40 50 Surfacefree energy (mJ m –2 ) Curing time (h) PBa PBZ-A1
Figure 11. Surface free energies of PBZs after various curing and annealing
times at 230◦C.
good thermal stability of the siloxane-imide-containing segment in BZ-A1 is able to improve the stability of the surface free energy during curing and annealing at high temperatures for long periods of time.
The three-liquid method of van Oss et al.36 was employed to calculate the surface free energy (γs) and the results are summarized in Table 4. When the curing temperature for the PBa system is 230◦C, the surface free energy decreases initially and then increases steadily with curing time (Fig. 11). The lowest surface free energy (16.6 mJ m−2) is obtained when curing at 230◦C for 1 h which then increases to 42.6 mJ m−2upon increasing the curing or annealing time. In this system, curing at 230◦C for 1 h provides the lowest surface free energy of 15.1 mJ m−2– a value that is even lower than those of Teflon37(21 mJ m−2) and PBa (16.6 mJ m−2), determined using the same liquids. The low surface free energy of PBZ-A1 may arise from the combination of benzoxazine groups and siloxane-containing segments. The incorporation of the siloxane segment in benzoxazine improves
the thermal stability while maintaining the low surface free energy after high-temperature thermal annealing for periods of time.
CONCLUSIONS
A novel siloxane-imide-containing benzoxazine (BZ-A1) was synthesized. The product from the curing of BZ-A1 (PBZ-A1) possesses extremely low surface free energy and improved thermal stability. This newly developed PBZ-A1 shows better stability of surface free energy under thermal curing and annealing, maintaining its low surface free energy compared with the conventional PBa.
REFERENCES
1 Drockenmuller E, Li LYT, Ryu DY, Harth E, Russell TP, Kim HC, et al,
J Polym Sci A: Polym Chem 43:1028 (2005).
2 Huang CC, Yang MS and Liang M, J Polym Sci A: Polym Chem 44:5875 (2006).
3 Wooster TJ, Abrol S, Hey JM and MacFarlane DR, J Polym Sci A: Polym
Chem 43:5072 (2005).
4 Liu YL and Hsieh CY, J Polym Sci A: Polym Chem 44:905 (2006). 5 Ning X and Ishida H, J Polym Sci A: Polym Chem 32:1121 (1994). 6 Takeichi T, Komiya I and Takayama Y, Kyoka-Purasutikkus 43:109
(1997).
7 Wang YX and Ishida H, Polymer 40:4563 (1999). 8 Macko JA and Ishida H, Polymer 42:227 (2001). 9 Holly FW and Cope AC, J Am Chem Soc 66:1875 (1944). 10 Burke WJ, Murdoch KC and Ec G, J Am Chem Soc 76:1677 (1954). 11 Burke WJ, Glennie ELM and Weatherbee C, J Org Chem 24:909 (1964). 12 Furukawa N, Jpn Kokai Tokkyo Koho 18:(2004).
13 Wang YX and Ishida H, Polym Mater Sci Eng 80:211 (1999). 14 Ishida H and Allen DJ, J Polym Sci B: Polym Phys 34:1019 (1996). 15 Kim HD and Ishida H, J Appl Polym Sci 79:1207 (2001). 16 Ishida H and Low HY, Macromolecules 30:1099 (1997). 17 Ishida H and Rodriguez Y, Polymer 36:3151 (1995).
18 Wang CF, Su YC, Kuo SW, Huang CF, Sheen YC and Chang FC, Angew
Chem Int Ed 45:2248 (2006).
19 Wang CF, Wang YT, Tung PH, Kuo SW, Lin CH, Sheen YC, et al, Langmuir
22:8289 (2006).
20 Liao CS, Wu JS, Wang CF and Chang FC, Macromol Rapid Commun
29:56 (2008).
21 Liao CS, Wang CF, Lin HC, Chou HY and Chang FC, J Phys Chem C
112:16189 (2008).
22 Wang CF, Chiou SF, Ko FH, Chen JK, Chou CT, Huang CF, et al, Langmuir
23:5868 (2007).
23 Chen KC, Li HT, Chen WB and Huang SC, presented at the 11th Pacific Polymer Conference, Cairns, 6–10 December (2009).
24 Liu YL, Hsu CW and Chou CI, J Polym Sci A: Polym Chem 45:1007 (2007). 25 Ardhyananta H, Wahid MH, Sasaki M, Agag T, Kawauchi T, Ismail H,
et al, Polymer 49:4585 (2008).
26 Takeichi T, Agag T and Zeidam R, J Polym Sci A: Polym Chem 39:2633 (2001).
27 Li HT, Chuang HR, Wang MW and Lin MS, Polym Int 54:1416 (2005). 28 Ghosh NN, Kiskan B and Yagci Y, Prog Polym Sci 32:1344 (2007). 29 Hemvichian K and Ishida H, Polymer 43:4391 (2002).
30 Agag T and Takeichi T, Macromolecules 36:6010 (2003). 31 Takeichi T, Kano T and Agag T, Polymer 46:12172 (2005).
32 Choi SW, Ohba S, Brunovska Z, Hemvichian K and Ishida H, Polym
Degrad Stab 91:1166 (2006).
33 Liu YL, Chiu YC and Wu CS, J Appl Polym Sci 87:404 (2003).
34 Good RJ and van Oss CJ, in Modern Approaches to Wettability: Theory
and Applications, ed. by Schrader ME and Loeb GI. Plenum Press,
New York, pp. 1–27 (1992).
35 Drelich J, Miller JD and Good RJ, J Colloid Interface Sci 179:37 (1996). 36 van Oss CJ, Chaudhury MK and Good RJ, Chem Rev 88:927 (1988). 37 Takei YG, Aoki T, Sanui K, Ogata N, Sakurai Y and Okano T,
