Photosensitive polymers with cinnamate units in the side position of ...

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2390 R. Mahy et al. / European Polymer Journal 42 (2006) 2389–2397 O HO C H H 3C H 2C CN CO 2Et photosensitive polymers are regarded as negativetype photoresists [6,7]. The substitution of the double bond of cinnamate group can affect its photosensitivity. It was reported that the withdrawing groups such as cyano group at the a-position of carbonyl function enhances the photoreactivity of cinnamate unit [8]. Brosse et al. [9] and Remmas et al. [10,11] have prepared and tested for photosensitivity different polystyrenic polymers with pendant cinnamate groups substituted on a-position by carboxylate and cyano groups. This article deals with the synthesis of new monomer [Ethyl a-cyano-4-(methacryloxy)cinnamate], its polymerization and copolymerization with C O CH 2 + O piperidine (pyridine) CN CH C CO2Et methyl methacrylate (Schemes 1 and 2). Monomer reactivity ratios and the ability to crosslink of the obtained polymers under UV irradiation were also investigated. 2. Experimental 2.1. Materials CN HO CH C CO2Et 1 2 3 (80 %) 4 (75 %) 1) Et 3 N / CH 2 Cl 2 2) H 2 C=C(CH 3 )-COCl Scheme 1. Synthesis of ethyl a-cyano-4-hydroxycinnamate 3 and ethyl a-cyano-4-(methacryloxy)cinnamate 4. H 2C C EtO 2 C CH 3 4 C O CH C O CN + MMA AIBN/ CHCl 3 65ºC CH 2 EtO 2 C C C O HC CH 3 C CN p CH 2 5 :Homopolymer (q=0) 6 : Copolymer Scheme 2. Synthesis of photosensitive homo- and co-polymers coming from 4. O C q CO2CH3 Solvents were distilled before use according to the procedures described in Perrin book [12] p- Hydrobenzaldehyde and AIBN were recrystallized in methanol. Methyl methacrylate was purified as follows: after washing twice with an aqueous solution of NaHCO3 (5%), and then twice with water, CH 3
it was dried over Na2SO4, and finally the dried filtrate was distillated under reduced pressure. Methacryloyl chloride was purified by distillation under vacuum. Ethyl cyanoacetate was used as received. 2.2. Apparatus Melting points were determined on a Bütchi apparatus. UV spectra were carried out on a Varian spectrophotometer (Cary Win UV B1O 100/300). Infrared spectra were recorded on a Perkin–Elmer 1750 Fourier-transform spectrometer. 1 H and 13 C NMR spectra were recorded on Avance DPX200 or Bruker AC 400 operating at 400.13 MHz for 1 H and 100 MHz for 13 CinCDCl3 or DMSO-d 6 with tetramethylsilane (TMS) as internal reference. The weight- and number-average molecular weights were determined by Size Exlusion Chromatography (SEC) on a Spectra SYSTEM AS1000 autosampler system, equipped with a guard column (Polymer Laboratories, PL gel 5 lm Guard, 50 · 7.5 mm) and two columns (Polmer Laboratories, 2 PL gel 5 lm MIXED-D columns, 300 · 7.5 mm) connected in series, and a Spectra SYSTEM RI-150 detector. Analyses were performed at 35 °C. THF was used as mobile phase at a flow rate of 1 ml min 1 . The system was calibrated using low polydispersity polystyrene standards (483–580 · 10 3 g mol 1 ). The photocrosslinking studies were peformed using a B100A Ultraviolet lamp emitting from 300 to 400 nm (100 w; k max = 365 nm). 2.3. Synthesis of ethyl a-cyano-4-hydroxycinnamate 3 A pyridine solution (7.5 ml) of p-hydoxybenzaldehyde 1 (25 mmol), ethyl cyanoacetate 2 (25 mmol) and piperidine (2 drops) was refluxed for 1 h in a round bottom flask fitted with a condenser. Then, the solution was poured drop by drop into a flask containing 100 ml of water and 25 g of crushed ice. The mixture was stirred until a product in suspension was formed. The precipitated material was filtered, washed with water, and then recrystallized in ethanol. Yield: 80%; mp 173 °C; IR (KBr): 3299 (OH), 2228 (C„N), 1714 (C@O), 1612 (C@sC); 1 H NMR (400 MHz, DMSO-d 6): d (ppm) 8.17 (s, 1H, HC@C), 7.95 (d, J = 11.4 Hz, 2H, Ar–H 2,6), 6.90 (d, J = 11.4 Hz, 2H, Ar–H 3,5), 4.25 (q, J = 7.2 HZ, 2H, CH3–CH2–O), 1.27 (t, J = 7.2 Hz, 3H, CH3–CH2–O); 13 C NMR (100 MHz, DMSO-d6): d (ppm) 164.1 (CO2Et), 162.6 (C4), 154.4 (CH@C), 133.8 (C2 and C6), 122.0 (C1), 116.6 (C3 and C5), R. Mahy et al. / European Polymer Journal 42 (2006) 2389–2397 2391 116.6 (CN), 98.4 (CH=C), 63.0 (CH3–CH2–O), 13.9 (CH3-CH2–O). 2.4. Synthesis of a-cyano-4-(methacryloxy)cinnamate 4 A solution of 3 (0.012 mol) in dichloromethane (12 ml) was introduced in a three necked roundbottom flask and cooled at 0 °C using an ice bath. Solutions of methacryloyl chloride (0.018 mol) in dichloromethane (6 ml) and triethylamine (0.018 mol) in dichloromethane (6 ml) were added simultaneously and dropwise from tow dropping funnels into the stirred mixture. At the end of addition, the ice bath was removed and the stirring was maintained for 12 h at room temperature. The formed triethylammonium chloride was filtered off and the filtrate was washed twice with a solution of sodium bicarbonate, twice with water, and then dried over sodium sulfate. Finally, the solvent of the dried filtrate was evaporated under reduce pressure and the crude product was recrystallized in ethanol. Yield: 75%; mp: 109 °C; IR (KBr): 2223 (C„N), 1743 and 1716 (C@O), 1614 (C@C); 1 H NMR (400 MHz, DMSO-d6): d (ppm) 8.25 (s, 1H, HC@C), 8.05 (d, J = 11.4 Hz, 2H, Ar–H2,6), 7.30 (d, J = 11.4 Hz, 2H, Ar–H3,5), 6.40 and 5.8 (s, 2H, H2C@C methacrylate), 4.38 (q, J = 7.2 Hz, 2H, CH3–CH2–O), 2.09 (s, 3H, CH3–CO), 1.42 (t, J = 7.2 Hz, 3H, CH 3–CH 2–O); 13 C NMR (100 MHz, DMSO-d 6): d (ppm) 164.3 (CO 2Et), 161.6 (CO-methacrylate), 153.8 (C4), 152.9 (CH@C), 134.6 (H2C@C-methacrylate), 131.8 (C2 and C6), 128.1 (C1), 127.4 (H2C@C methacrylate), 121.8 (C3 and C5), 114.6 (CN), 101.9 (CH@C), 62.0 (CH3–CH2–O), 17.5 (CH3-methacrylate), 13.3 (CH 3–CH 2–O). 2.5. Synthesis of homopolymer 5 In a round-bottom flask fitted with a condenser were introduced 0.23 mmol of monomer 4, 5 ml of chloroform, and 0.023 mmol of AIBN (1% compared to 4). The mixture was swept by nitrogen, and then heated at 65 °C. After the required time (8 h), the obtained mixture was poured in a large excess of methanol (20 ml). The precipitated polymer was washed with methanol, then purified by repeated reprecipitation into methanol from solution in chloroform, and finally dried under vacuum. Yield: 92%; IR (KBr): 2225 (C„N), 1756 and 1716 1 (C@O), 1613 (C@C); H NMR (400 MHz,
Page 1: Photosensitive polymers with cinnam
Page 5 and 6: Conversion of 4 (%) 80 70 60 50 40
Page 7 and 8: Table 2 Molar fractions of 4 in fee
Page 9: national program of research (Actio

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