Synthesis and characterization of novel jacketed polymers and investigation of their self assembly and application 4

Chapter Synthesis and characterization of novel polymeric complexes with side-chain pyrimidine groups 112 4.1 Introduction Polymeric complexes in the solid state are considered to be promising for the development of smart materials that are characterized by the formation of supramolecular structures through self-assembly process. Self-assembled materials formed by the noncovalent bonds have attracted much interest owing to easy synthesis and high processibility 1,2. Complexes between polymers and amphiphilic surfactants through noncovalent bonding offer novel properties and phase structures not possessed by the individual components. In the solid state, the complexes self-assemble into ordered structures via a delicate balance of attractive and repulsive interactions. Dynamic molecular complexes can be prepared via the self-assembly process using non-covalent bonding. For example, hydrogen-bonded liquid crystal polymers, which include main-chain, side-chain, and network structures, have been prepared by the self-organization of polymers and small molecules. The noncovalent interactions play a key role in the formation of assembled structures, and possibility to design novel functional materials 3. Kato et al. reported first supramolecular hydrogen bonded liquid crystalline polymeric complexes4, in which polyacrylate with a benzoic acid moiety on the side chain was complexed with stilbazole ester moiety. The complexes showed a nematic phase up to 252 °C. Ionic interaction, metal coordination and hydrogen bonding interactions were employed to form ordered nanostructures5-10. Kato et al. also reported complexes formed via poly(vinylpyridine) and nonadecylphenol exhibited layered smectic structures due to the microsegregation of different amphiphilic groups.11 Antonietti et al. have studied polyelectrolyte-surfactant (eg. poly(n- 113 alkyltrimethylammonium styrene sulfonate) complexes which show an ordered lamellar structure with ionic and nonpolar alkyl layers organized in an alternating layers12-13. Ikkala et al. reported the formation of hierarchical structures from a complex prepared from polystyrene-block-poly(4-vinylpyridine), pentadecylphenol, and methane sulfonic acid14-15. Two structural changes occurred in the lattice: microseparation of block copolymers and complexation as a function of temperatures cause drastic electrical conductivity changes. By tailoring the relative ratio of the components, lamellar and cylindrical structures were obtained14-20. Hollow cylinders were formed in a glassy rigid PS medium from polystyrene-block-poly(4-vinylpyridine), and pentadecylphenol. Part of the supramolecular template (pentadecylphenol) can be conveniently removed after the structure has been formed17-19. In general, when there is a good balance between attractive and repulsive interactions, microphase-segregation is induced in the system. The phase behaviors of polymeramphiphilic systems can be modified through tailoring the attractive and repulsive interactions in the systems. This can be realized via modifying the length of the alkyl chain and change of the interaction of hydrogen bonding. Here we report the structure properties investigation of polymers poly (4-dodecyloxy-2,5- bis(pyrimidin-5-yl)-phenyl1-yl methacrylate), poly(4-pyrimidin-5-yl-phenyl methacrylate) with the pyrimidine group as the base functional group, study the complexes formed via host polymers with pyrimidine groups and alkyl sulfonic acid and investigate their self-assembling properties in the solid state. 114 4.2 Experimental section 4.2.1 Materials and reagents All reagents and solvents were obtained from commercial supplies and used without further purification unless noted otherwise. Tetrahydrofuran (THF) was distilled over sodium and benzophenone under N2 atmosphere. N,N-dimethylformamide (DMF) was dried with molecular sieves (4 Å, Aldrich). Flash column chromatography was performed using 60-120 mesh silica gel (Aldrich). Dibenzoyl peroxide (BPO) was recrystallized from chloroform-methanol solution as glistening crystals, and used as initiators for polymerization. 4.2.2 Instrumentation Fourier transform infrared (FT-IR) spectra were obtained using a Perkin-Elmer 1616 FTIR spectrophotometer as KBr discs. 1H NMR, 13 C NMR spectra were recorded on a Bruker ACF 300 MHz spectrometer. Differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA) were recorded using a TA-SDT2960 and a TA-DSC 2920 at a heating rate of 10 °C min-1 under N2 environment. Gel permeation chromatographic (GPC) analysis were conducted with a Waters 2696 separation module equipped with a Water 410 differential refractometer HPLC system and Waters Styragel HR 4E columns using THF as eluent and polystyrene as standard. The XRD patterns were recorded on a powder diffractometer with a graphite monochromator using 1.54 Å Cu Kα wavelength at room temperature (scan rate: 0.05 o/s; scan range 1.5-30 o). A Zeiss Axiolab POM equipped with a Linkam LTS 350 hot stage was used to observe anisotropic textures. All AFM images were recorded with a Digital Instruments (DI) Multimode SPM IIIa system in contact mode using square pyramid Si3N4 probes (25 °C, 115 in air). All films were prepared using spin coating of polymer solutions in THF (0.5 mg/ml) onto a glass slide at 2000 rpm. Melting points (Mp) were obtained on a BÜCHI Melting Point B-540 apparatus and are uncorrected. 4.2.3 Synthesis of the host polymer The host polymers: poly(4-pyrimidin-5-yl-phenyl methacrylate) (P1), poly (4Dodecyloxy-2,5-di(pyridin-5-yl)phenyl-1-yl methacrylate) (P2), poly (4-Dodecyloxy2,5-di(pyrimidin-5-yl)phenyl-1-yl methacrylate) (P3) were synthesized according to Scheme 4.1. n O BPO/THF O N O N O N N N N N OC12H25 N OC12H25 P1 OBn OH OBn OBn BnBr N N i,n-BuLi/THF K2CO3/DMF Pd(PPh3)4 ii, B(O-i-Pr)3 Br B(OH)2 Br Br Toluene/EtOH/2M Na2CO3 N N OH O Cl Pd/C H2 n BPO/THF O O O O Et3N/THF N N N N N N P2 116 OBn OBn Br B(OH)2 N N N Pd(PPh3)4 (HO)2B Toluene/EtOH/2M K2CO3 OC12H25 C12H25O OH O O Cl H2 N N Pd/C Et3N O N N C12H25O OC12H25 n BPO/THF O O N N OC12H25 P3 Scheme 4.1. Synthesis route for monomer and polymers 1-benzyloxy-4-bromo-benzene (2) In a 250 ml round-bottom flask with a stirring bar was placed 17.3 g 1,4-dibromophenol (0.1 mol), 27.3 g K2CO3 (0.2 mol) and 150 ml acetone. The mixture was purged with N2 for 20 min, heated to 60-70 °C under nitrogen atmosphere. 17.8 ml (0.15 mol) of benzyl bromide was added dropwise. After finishing the addition, the reaction mixture was stirred for 18 h, cooled to RT and filtered. The solution was concentrated and poured into water. The pH of water was adjusted to about 6. The resulted precipitate was recrystallized in ethanol to yield a white crystal. Yield: 21.4 g (81.6 %). 1H NMR (300 MHz, DMSO-d6, δ ppm) 7.45 - 6.97 (m, Ar-H, H), 5.09 (s, Ar-CH2-O, H). 13C NMR 117 (75.4 MHz, DMSO-d6, δ ppm) 157.5, 136.6, 132.1, 128.4, 127.8, 127.6, 117.1, 112.0 (ArC), 69.4(O-CH2-Ar). MS (EI): m/z: 264.0, 262.0, 91.1, 65.0. Mp: 64 °C. 4-Benzyloxy-phenyl-2-boronic acid (3) In a 500 ml round-bottom flask with a stirring bar was placed 10.5 g (40 mmol) of 1benzyloxy-4-bromobenzene and 150 ml dry THF. The solution was cooled to - 78 °C and then a 1.6 M solution of butyllithium in hexanes (75 ml, 0.12 mol) was added slowly under a nitrogen atmosphere. The solution was stirred at -78 °C for another h, followed by the dropwise addition of triisopropylborate (50 ml, 0.18 mol). After complete addition, the mixture was warmed to RT, stirred overnight, and mixed with 200 ml of deionized water. The organic phase was collected and dried with MgSO4 and filtered, and the solvent was removed under reduced pressure. The resulted light yellow solid was recrystallized from acetone. Yield: 8.4 g (92.2 %). 1H NMR (300 MHz, DMSO-d6, δ ppm) 7.83 (s, B-OH, H), 7.73-6.95 (m, Ar-H, H), 5.11 (s, Ar-CH2-O, H). 13C NMR (75.4 MHz, DMSO-d6, δ ppm) 161.5, 141.6, 132.1, 128.4, 127.8, 127.6, 117.1, 112.0 (Ar-C), 68.2 (O-CH2-Ar). MS (EI): m/z: 228.2, 184.2, 91.1. Mp: 185 °C. 5-(4-Benzyloxyphenyl) pyrimidine (4) A 250 ml round bottom flask equipped with a condenser was charged with 4.56 g (20 mmol) of 4-benzyloxy-phenyl-2-boronic acid and 2.12 g (13.3 mmol) of 5-bromopyrimidine, 60 ml toluene, 20 ml methanol and 60 ml sodium carbonate (2M). The mixture was degassed via cycles, before the catalyst of 0.2g tetrakis (triphenylphosphine) palladium (2 mol%) was added in dark under argon atmosphere. The flask was degassed once more and charged with argon. The reaction mixture was heated to 100 °C for 48h, before being allowed to cool to RT and then filtered. The liquid 118 layer was separated with a separation funnel, and the aqueous layer was extracted with toluene (100 ml × 2). The toluene layer was combined and washed with × 100 ml water and dried over MgSO4. The solvent was then removed under reduced pressure, and the resulting crude product was purified using column chromatography on a silica gel using hexane and ethyl acetate (2:1) as the eluant. Yield: 2.5g (44.3 %). 1H NMR (300 MHz, DMSO-d6, δ ppm) 9.2 - 9.1 (m, ArH, H), 7.75 - 7.12 (m, Ar-H, H), 5.19 (s, Ar-CH2-O, H). 13C NMR (75.4 MHz, DMSO-d6, δ ppm) 158.5, 157.5, 154.0, 136.6, 132.7, 128.4, 128.1, 127.8, 127.6, 126.0, 115.0 (Ar-C), 69.3(O-CH2-Ar). MS (EI): m/z: 262.1, 172.1, 91.1. Mp: 295 °C. 4-(Pyrimidin-5-yl) phenol (5) To a 100 ml round-bottomed flask containing 10 % Pd/C (1.0g) in 50 ml THF was added 5-(4-benzyloxyphenyl) pyrimidine (2.17 g, mmol). The flask was charged with nitrogen, and a balloon filled with H2 was fitted to the flask. The nitrogen gas was briefly evacuated from the flask, and the H2 gas was charged above the solution. The reaction mixture was stirred for 24 h at ambient temperature and then filtered through a glass frit containing a small layer of celite powder. After the solid was washed with THF (3 × 25 ml), the organic phrases were combined and the solvent was then removed with a rotary evaporator to yield a light yellow solid. The resulting crude product was purified by column chromatography on a silica gel column using hexane and ethyl acetate (1:4) as the eluant. Yield: 1.4 g (98.2 %). 1H NMR (300 MHz, DMSO-d6, δ ppm) 9.10 - 9.04 (m, ArH, H), 7.63 (d, J = 8.4 Hz, Ar H), 6.90 (d, J = 8.2 Hz, Ar H), 6.87 (b, O-H, H). 13C NMR (75.4 MHz, DMSO-d6, δ ppm) 148.8, 136.6, 128.4, 127.8, 127.6, 119.6, 108.3(ArC). MS (EI): m/z: 172.1, 118.1, 91.1. Mp: 116 °C. 119 4-(Pyrimidin-5-ylphenyl) methacrylate (6) Triethylamine (2.5 ml, 17.9 mmol) and 4-(pyrimidin-5-yl) phenol (1.0 g, 5.8 mmol) were dissolved in 30 ml dry THF placed in a 100 ml round-bottom flask. This solution was cooled to °C, and added a solution of methacryloyl chloride (1.2 ml, 12 mmol) in ml THF. After finishing the addition, the reaction mixture was warmed to room temperature and stirred for hr, filtered and the volatile components were removed under reduced pressure. The resulting crude product was dissolved in dichloromethane, washed with sodium bicarbonate solution, followed by water (3 × 50 ml). The organic layer was dried over anhydrous magnesium sulfate and filtered. The excess solvent was removed under reduced pressure and the resulted compound was purified using flash column chromatography on a silica gel column with hexane and ethyl acetate (1:1) as the eluent to yield the monomer. Yield: 0.85 g (61.0 %). 1H NMR (300 MHz, CDCl3, δ ppm) 9.20 (s, ArH, 1H), 8.95 (s, ArH, 2H), 7.63 (d, J = 8.4 Hz, ArH, H), 6.90(d, J = 8.2 Hz, ArH, H), 6.39 (s, C=CH2, H), 5.80 (s, C=CH2, H), 2.09 (s, -CH3, 3H). 13 CNMR (75.4 MHz, CDCl3, δ ppm) 157.5, 154.8, 151.7, 129.1, 128.0, 127.7, 123.8, 122.8, 121 (Ar-C), 18.2(-CH3). MS (EI): m/z: 240.1, 172.1, 118.1, 84.0. Mp: 127 °C. 1-Benzyloxy-4-dodecyloxy-2, 5-di(pyridin-5-yl) benzene (7) Compound was synthesized according to the procedure described for the synthesis of 5(4-benzyloxy-phenyl) pyrimidine. Yield: 4.8 g (65.2 %). 1H NMR (300 MHz, CDCl3, δ ppm): 8.66 - 8.64 (m, Ar-H, H), 7.54 - 7.26 (m, ArH, H), 7.06 (s, ArH, H), 7.00 (s, ArH, H), 5.05 (s, O-CH2-Ar, H), 3.96 (t, J = 6.3 Hz, O-CH2-, H), 1.76 (p, J = 7.5 Hz, C(O)-CH2-, H), 1.26 (b, -CH2- 18 H), 0.88 (t, J = 6.7 Hz, -CH3, H). 13C NMR (75.4 MHz, CDCl3, δ ppm): 157.0, 156.7, 150.8, 149.5, 140.9,131.5, 128.6, 128.2, 127.2, 120 20.4,115.9, 114.6, 106.2 (Ar-C), 71.7, 69.5 (O-CH-), 318, 29.5, 29.4, 29.3, 29.2, 29.1, 29.0, 25.9, 22.6 (-CH2-), 14.8 (-CH3). MS (EI): m/z: 522.4, 353.1, 263.1, 91.1. Mp: 129.5 °C. 4-Dodecyloxy-2, 5-di(pyridin-5-yl) phenol (8) Compound was synthesized according to the procedure described for the synthesis of compound 5. From 4.0 g (7.7 mmol) of compound was obtained 2.8 g of light yellow powder. Yield: 2.8 g (84.1 %). 1H NMR (300 MHz, CDCl3, δ ppm): 8.60 - 8.57 (m, ArH, H), 7.60 - 6.95 (m, Ar-H, H), 3.92 (t, J = 6.3 Hz, O-CH2-, H), 3.60 (b, O-H, H), 1.73 (q, J = 6.4 Hz, C(O)-CH2-, H), 1.25 (b, -CH2- 18 H), 0.87 (t, J = 6.0 Hz, -CH3, H). 13C NMR (75.4 MHz, CDCl3, δ ppm): 150.2, 149.0, 148.6, 148.0, 124.4, 122.0, 117.5, 114.8, 106.4 (Ar-C), 68.8 (O-CH2-), 31.2, 28.9, 28.8, 28.7, 28.6, 28.5, 28.2, 25.4, 22.2, 20.2 (-CH2-), 14.1 (-CH3). MS (EI): m/z: 432.3, 264.1, 237.1. Mp: 150 °C. 4-Dodecyloxy-2, 5-di(pyridin-5-yl) phenyl-1-yl methacrylate (9) Monomer was synthesized according to the procedure described for the synthesis of monomer 6. From 2.5 g (5.8 mmol) of compound and 1.6 ml (11.6 mmol) methacryloyl chloride was obtained 0.65 g (26.0 %) of monomer. H NMR (300 MHz, CDCl3, δ ppm): 8.65 - 7.2 (m, Ar-H, 10 H), 6.17 (s, CH=C, H), 5.65 (s, C=CH, H), 4.00 (t, J = 6.0 Hz, -O-CH2-C-, H), 1.90 (s, C=C-CH3, H), 1.74 (p, J = 6.5 Hz, R(O)-CH2-, H), 1.24 (b, -CH2-, 18 H), 0.86 (t, J = 6.5 Hz, -CH3, H). 13 C NMR (75.47 MHz, CDCl3, δ ppm): 171, 149.80, 149.45, 141.17, 137.08, 136.62, 135.76, 134.62, 134.49, 133.79, 130.59, 129.33, 128.88, 126.63, 124.90, 124.07, 123.45, 113.72, 77.33, 76.91, 76.48, 69.11, 31.79, 30.79, 29.51, 29.11, 25.98, 22.56, 21.11, 18.13, 14.02. EI-MS: m/z: 500.2, 345, 331.9, 263, 86, 69. 121 Poly(4-Dodecyloxy-2, 5-di(pyrimidin-5-yl)phenyl-1-yl methacrylate) (P1) P1 was described in chapter as P03 Poly(4-(pyrimidin-5-yl )phenyl methacrylate) (P2) Polymerization of monomer was performed according to the procedure described for P1. From 0.8 g (2.0mmol) of monomer was obtain a light yellow powder. Yield: 0.5 g (62.5%). 1H NMR (300 MHz, DMSO-d6, δ ppm) 9.20-6.90 (m, ArH, H), 1.95 (b, -CH-, H), 1.74 (b, -CH3, H). FT-IR (KBr, cm-1): 3041 (ArH stretching), 2958 (-CH2stretching), 1745 (ester C=O stretching), 1555, 1508, 1415 (Ar, C=C, C=N stretching). 1259, 1170, 1101 (C-O-C stretching). Mn: 0.60 × 104; Mw: 0.89 × 104; PD: 1.5. Poly(4-Dodecyloxy-2, 5-di(pyridin-5-yl) phenyl-1-yl methacrylate) (P3) Polymer P3 was performed according to the procedure described for polymer P1. From 0.5 g (1 mmol) of compound was obtained as light yellow polymer. Yield: 0.2 g (40%). 1H NMR (300 MHz, CDCl3, δ ppm): 8.65 - 6.97 (b, ArH, 10 H), 4.00 (b, -O-CH2-, H), 1.75-1.65 (m, -CH2-, H), 1.24 (b, -CH2-, 18 H), 0.86 (b, -CH3-, H). FT-IR (KBr, cm-1): 3041 (ArH stretching), 2958 (-CH2- stretching), 1745 (ester C=O stretching), 1595, 1548, 1410(Ar, C=C, C=N stretching). 1274, 1170, 1101 (C-O-C stretching). Mn: 0.62 × 104; Mw: 1.16 × 104; PD: 1.9. 4.2.4 Preparation of complexes Appropriate amounts of host polymer and dodecylbenzenesulfonic acid (DBSA) were separately dissolved in appropriate solvent (for P1, in THF; for P2, P3, in DMF). The concentration of the solution was 50 mg/ml. The DBSA solution was added dropwise to the host polymer solution and the mixture was kept stirring for days in room temperature before evaporating the solvent. The complexes were further dried at 50 °C in 122 high vacuum for two days. The complexes are marked as Pn(DBSA)x, where x is the number of DBSA molecules per repeating unit of the host polymer. 4.3 Results and Discussion 4.3.1 FTIR characterization The interaction of the two components in complexes can be investigated using FTIR spectroscopy, where the frequency shifts of the absorption bands of functional groups provide information on the nature and intensity of the interactions. Figure 4.1 shows the FTIR spectra of P1(DBSA)x, where the x is 0.5, 1.0 and 2.0 respectively. The pyrimidine is weaker base than pyridine, usually the second C=N groups in pyrimidine ring are very difficult to protonate after the first protonation. -1 1223 cm -1 1619 cm x= 2.0 -1 1552 cm Absorbance (a.u.) -1 1619 cm x= 1.0 -1 1552 cm -1 x= 0.5 1619 cm -1 1552 cm 500 1000 1500 2000 P1 2500 3000 3500 4000 -1 Wavenumber (cm ) Figure 4.1. FTIR spectra of P1(DBSA)x and the host polymer P1 The stretching peak at 1552 cm-1 from pyrimidine groups of the host polymer is strongly affected with the formation of the complexes. With the increase of the content of the DBSA, the peak at 1552 cm-1 decreases and a new peak at 1619 cm-1 appears. It is known 123 that a strong acid such as DBSA is capable of protonating the pyridine ring to form a pyridinium ring7. Similiarly, it is reasonable to attribute the peak at 1619 cm-1 to the vibration of the pyrimidinium groups. When x = 2.0, it is expected that all pyrimidine groups were protonated by DBSA, and the peak at 1552 cm-1 was observed to all shifted to the 1619 cm-1. It is also noted that the peak at about 1220 cm-1 increases with the increase of DBSA. This may be due to the increase of the SO3- in DBSA with the deprotonation of –SO3H. It is important to note that a large shift of 66 cm-1 was observed upon full complexation. This evidence supports that the acidic proton of DBSA is completely transferred to the pyrimidine ring, the interaction has strong ionic character between the positively charged pyrimidinium ring and negatively charged sulfonate anion. Therefore, the proton transfer rather than hydrogen bonding is expected to take place. Figure 4.2 shows the FTIR spectra of P2(DBSA)x, where the x is 0.3, 0.75 and 1.0 respectively. -1 1185 cm 1612 cm-1 x= 1.0 -1 1608 cm Absorbance (a.u.) x= 0.75 -1 1555 cm -1 1608 cm x= 0.3 -1 1555 cm 500 1000 1500 P2 2000 2500 3000 3500 4000 -1 Wavenumber (cm ) Figure 4.2. FTIR spectra of P2(DBSA)x and the host polymer P2 124 Similarly the characteristic peak at 1555 cm -1of the P2 with pyrimidine groups was observed to shift to 1612 cm –1 with the full complexation and the increase of the peak at around 1190 cm -1 means the increase of the SO3- groups upon deprontonation, which support the formation of the complexes. A shift of 57 cm-1 corresponding to the formation of a pyrimidinium ring is observed, however it is a weaker band compared with P2(DBSA)x. Figure 4.3 shows the FTIR spectra of P3(DBSA)2.0 and host polymer P3. The polymer P3 with pyridine groups in side chain shows characteristic peaks at 1595, 1547, and 1410 cm-1 due to the C=C vibration. The peak at 1595 cm-1 is observed to shift to 1628 cm-1 and the peak at 1210 cm-1 is shown obviously an increase upon full complexation. -1 Absorbance (a.u.) 1210 cm -1 1628 cm X= 2.0 -1 1595 cm P3 500 1000 1500 2000 2500 3000 3500 4000 -1 Wavenumber (cm ) Figure 4.3. FTIR spectra of P3(DBSA)2.0 and the host polymer P3 125 4.3.2 Thermal analysis Thermally induced phase transition behaviors of complexes P1(DBSA)x were evaluated by differential scanning calorimetry (DSC) in a nitrogen atmosphere. The DSC traces are shown in Figure 4.4. o P1 o Tg 29.9 C tiso 107.5 C x= 0.5 o o heat flow (mW) Tg 29.3 C tiso 88.8 C x= 1.0 o Tg 27.8 C x= 2.0 o Tg 36.6 C -50 50 100 150 200 250 o Temperature ( C) Figure 4.4. DSC curves of the first heating scan for complex P1(DBSA)x and host polymer P1 In the previous study, it is demonstrated that the polymer P1 (described as P03 in chapter 2) is a liquid crystalline polymer, which undergoes an isotropic transition at 107.5 °C with a Tg at 29.3 °C. For the complexes P1(DBSA)x, with x = 0.5, the complex shows two endothermic transitions, whereas the isotropic transition at 88.8 °C decreases obviously compared with the pristine polymer P1. When x increase to 1.0 and 2.0, the second endothermic transitions disappear with only the glass transitions are observed, which appear at 27.8 and 36.8 °C respectively. It is noted that Tgs of the complexes don’t 126 decrease with the increase of the DBSA though DBSA contains a long flexible alkyl chain. This may be attributed to two factors: one, the host polymer already have a long flexible alkyl chain, thus the plasticized effect is not so obvious with the addition of DBSA, but the ionic effect from complexes enhances the interaction, then exert some influence on the Tg. Both combined effects might explain the change in the Tg of the complexes. Figure 4.5 shows the DSC curves for host polymer P2 and complexes P2(DBSA)x (x= 0.3, 0.75, 1.0). P2 exhibits a clear glass transition (Tg) at 135.3oC. With the increase of DBSA (from x= 0.3 to x= 0.75), the Tgs of complexes decrease from 135.3 °C to 99.0 °C and 64.5 °C, respectively. That change may be due to the increase of the long flexible alkyl chains with the inlet of DBSA. It is interesting that P2(DBSA)1.0 shows two endothermic transitions. Besides the Tg at 73.4 °C, a small transition appears at 137 °C, which may be an isotropic transition. However, POM and X-ray cannot detect this change. Figure 4.6 shows the DSC traces for host polymer P3 and complexes P3(DBSA)2.0. The host polymer shows three endothermic transitions at 88.3, 100.3 and 135.7 °C, respectively. P3(DBSA)2.0 appears two transitions at 89 and 138.6 °C. Compared with curve of host polymer P3, the peak in P3(DBSA)2.0 appears broader. 127 o Heat Flow (mW) Tg: 73.4 C x= 1.0 o T1: 137 C x= 0.75 o Tg: 64.5 C x= 0.3 o Tg: 99 C o Tg: 135 C 50 100 P2 150 200 250 o Temperature ( C) Figure 4.5 DSC curves of the first heating scan for complex P2(DBSA)x and host polymer P2 P3 o o T1: 88.3 C o T3:135.7 C Heat Flow (mW) T2: 100.3 C x = 2.0 o T2: 138.6 C o T1: 89 C 50 100 150 200 250 o Temperature ( C) Figure 4.6 DSC traces of the first heating scan for complex P3(DBSA)1.0 and host polymer P3 128 4.3.3 POM study The novel polymeric complexes P1(DBSA)x were analyzed with polarized optical microscopy to identify the mesophase of the pristine polymer and complexes (shown in Figure 4.7). When the isotropic liquid of P1 was cooled with a rate of 0.5 °C min-1 to 95 °C, a mosaic texture was formed (shown in Figure 4.7a) and complex P1(DBSA)0.5 exhibited a typical focal-conic fan texture of smectic A phase 22 when cooled to 78 °C from a isotropic melt (Figure 4.7b) while no birefringent textures were found from other complexes P1(DBSA)1.0 and P1(DBSA)2.0 during cooling. It is well known that the broad polydispersity of polymers will cause hindrance to form mesophase by polymers, which may explain the lack of recognizable textures from the polymer P1 23. For P1(DBSA)0.5, DBSA may act as a plasticizer to enhance the packing during cooling, thus a typical smectic mesophase is formed. However, with the increase of the amount of DBSA, the order disappeared totally. 4.3.4 X-ray diffraction analysis XRD measurements were carried out to collect more information on the molecular arrangements and packing model of novel complexes. X-ray diffraction patterns for pristine polymer P1, P1(DBSA)0.5 and P1(DBSA)1.0 are shown in the Figure 4.8. The dspacing distance was derived using the Bragg’s law d = nλ/2sin(θ) (λ = 1.54 Å). The reflection angle 2θ and the space distance d are listed in Table 4.1. 129 b a Figure 4.7. Polarized optical micrographs of (a) P1 observed at 95 °C on cooling with a 0.5 °C min-1 from isotropic melt, (b) P1(DBSA)0.5 observed at 78 °C on cooling with 1.0 °C min-1 from isotropic melt. relative intensity(a.u.) P1(DBSA)1.0 P1(DBSA)0.5 o 29.4 A O 35.9 A o 11.9 A o 30.6 A P1 o 18.0 A 10 15 20 25 2-theta(degree) Figure 4.8 X-ray diffraction patterns of polymer P1, P1(DBSA)0.5 and P1(DBSA)1.0. 130 Table 4.1. Peak angles (°) and d spacings (Å) for the complexes P1(DBSA)x Polymer 2θ1/° 2θ2/° 2θ3/° 2θ4/° 2θ5/° d1(Å) d2(Å) d3(Å) d4(Å) d5(Å) 2.46 2.86 P1(DBSA)0.5 3.02. 20.1 P1 4.91 7.42 19.8 35.9 30.6 29.4 4.4 17.9 11.9 4.5 The XRD diffraction pattern of P1 shows sharp reflection in the small angle region at 2θ = 2.46, 2.86 and 4.91o, from which d spacings of 35.9 Å, 30.6 Å and 17.9 Å are derived. It also offers a sharp reflection in the middle angle region and a broad halo at 2θ = 7.42 and 19.9 o, from which d spacings of 11.9Å and 4.5 Å are derived. The XRD diffraction pattern of complex P1 (DBSA) 0.5 shows one reflection in the small angle region at 2θ = 3.02 o, from which d spacing of 29.4Å can be calculated, whereas the P1(DBSA)1.0 bear no reflection in the diffraction pattern. The P1(DBSA)0.5 lattice appeard to have some long-range order, however, the reflection in the small angle is broader than that of host polymer and the reflection in middle angle region is missed, which indicates that the ordered packing decreases compared with that of the host polymer . With the increase of the amount of DBSA, and the decrease of the free pyrimidine groups, long-range order disappears. In the previous study on the novel jacketed polymer P1 (described in chapter as P03), a 2D rectangular columnar mesophase was determined. The pyrimidine groups on the terminal position play a critical role in the self-assembly of the polymer, which helps to pack the polymer chains in ordered structures24-27. With the addition of DBSA, the longrange order is difficult to form inside the lattice. When the polymers were combined with 131 excess of DBSA, the polar and stabilizing effect of pyrimidine groups is decreased and the side flexible chains in the lateral position interfere with the packing of the mesogenic units, which results in more disorder in the lattice. X-ray diffraction patterns for pristine polymer P2, P2(DBSA)1.0 are shown in the Figure 4.9. The reflection angle 2θ and the space distance d are listed in Table 4.2. The diffraction pattern for P2 only exhibits one broad halo at 2θ = 19.6o, and no sharp reflection is found, which indicates that the polymer is short of any long-range position order. P2(DBSA)1.0 shows a series of peaks at middle and large angler region. That may be due to the crystallization of the long alkyl chain from DBSA28. Further investigation is Intensity (a.u.) needed to explain the results fully. x= 1.0 P2 10 15 20 25 30 2-theta (degree) Figure 4.9. X-ray diffraction patterns of polymer P2, and P2(DBSA)1.0. 132 Table 4.2. Peak Angles (°) and d spacing (Å) for the complexes P2(DBSA)1.0 Polymer 2θ1(°) 2θ2(°) 2θ3(°) 2θ4(°) 2θ5(°) d1(Å) d2(Å) d3(Å) d4(Å) d5(Å) P2(DBSA)1.0 12.5 P2 19.6 16.6 18.9 24.4 26.1 7.86 5.93 5.21 4.04 3.78 5.02 4.3.5 Morphology study By using atomic force microscopy (AFM), the morphology of the polymeric complex was investigated. AFM analyses were performed on spin-coated films on a glass sheet. The AFM images from P1 and P1(DBSA)0.5 are displayed in Figure 4.10. The image from P1 (Figure 4.10a) displays a well-ordered fibrous structure, which is characteristic of cylindrical rod type polymers whereas the image from P1(DBSA)0.5 (Figure 4.10b) shows a particle structure, which is dramatically different from that of the pristine polymer P1. The component DBSA exerts a significant effect on the materials packing. This can be attributed to the decrease in the effect of pyrimidine groups with the increase of amounts of DBSA. The diameter of the fiber from pristine polymer is about 100 nm while the diameter of the particle from complex is much bigger, almost at µm. After annealed at 60 °C for different time intervals, P1(DBSA)0.5 was investigated with AFM about the thermal effect on the morphologies of complexes. The images are shown in Figure 4.10c (after annealed for 4h) and d (after annealed for h). The images show that porous structures were formed from the particle structure. This may be due to decomposition of the complex after annealing. 133 a b c d Figure 4.10. AFM images (contact mode) of film on glass slide by spin-coated from a solution (0.5 mg/ml) in THF (a) pristine polymer P1; (b) complex P1(DBSA)0.5; (c) P1(DBSA)0.5 after annealed at 60 °C for 4h; (d ) P1(DBSA)0.5 after annealed at 60 °C for 8h. 4.3.6 Conclusion A series of complexes base on Poly (4-Dodecyloxy-2, 5-di (pyrimidin-5-yl)-phenyl-1-yl methacrylate) and dodecylbenzenesulfonic acid were prepared. FTIR studies show that the vibrating brand at 1552 cm-1 corresponding to the pyrimidine ring in host polymer shifts to 1634 cm-1 corresponding to pyrimidinium ring in complexes, which indicates the 134 proton transfer rather than hydrogen bonding is considered to take place. DSC, POM and X-ray diffraction results show that only when the DBSA content is low (x=0.5), the complexes keep the liquid crystal properties and appear a lamella structure. P1(DBSA)0.5 takes a particle morphology which is contrast to the fibrous state of pristine polymer. A porous structure is formed after annealing the complexes, which may provide an easy way to prepare the porous materials. A series of complexes from poly(4-Dodecyloxy-2, 5-di (pyridin-5-yl) phenyl-1-yl methacrylate) or poly (4-(pyrimidin-5-yl) phenyl methacrylate) and dodecylbenzene sulfonic acid were prepared. However, no long-range order was detected in these complexes in the X-ray diffraction studies. References 1. Thunemann, A. F. Prog. Polym. Sci. 2002, 27, 1473-1572. 2. Zhou, S.; Chu, B. Adv. Mater. 2000, 8, 545-556. 3. Kato, T.; Mizoshita, N.; Kanie, K. Macromol. Rapid Commun. 2001, 22, 797814. 4. Kato, T.; Frechet, J. M. Macromolecules 1989,22, 3818-3822. 5. Kato, T.; Kihara, H.; Ujiie, S.; Uryu, T.; Frechet, J. M. Macromolecules 1996, 9, 8734-8739. 6. Kawakami, T.; Kato, T. Macromolecules 1998, 31, 4475-4479. 7. Ikkala, O.; Ruokolainen, J.; Brinke, G. ten; Toekkeli, M.; Serimaa, R. Macromolecules 1995, 28, 7088-7094. 8. Jiao, H., Goh, S. H.; Valiyaveettil, S. Macromolecules 2001, 34, 7162-7165. 135 9. Valkama, S.; Ruotsalainen, T.; Kosonen, H.; Ruokolainen, J. Torkkeli, M.; Serimaa, R.; Brinke, G. ten; Ikkala, O. Macromolecules 2003, 36, 3986-3991. 10. Valkama, S.; Lehtonen, O.; Kosonen, H.; Torkkeli, M.; Serimaa, R.; Brinke, G. ten; Ikkala, O. Macromol. Rapid Commun. 2003, 24, 556-560. 11. Kato, T.; Nakano, M.; Moteki, T.; Uryu, T.; Ujiie, S. Macromolecules 1995, 28, 8875-8876. 12. Antonietti, M.; Conrad, J. Angew. Chem. Int. Ed. Engl. 1994, 33, 1869-1870. 13. Antonietti, M.; Conrad, J.; Thunemann, A. F. Macromolecules 1994, 27, 60076011. 14. Ruokolainen, J.; Brinke, G. ten; Ikkala, O.; Torkkeli; M.; Serima, R. Macromolecules 1996, 29, 3409-3415. 15. Ruokolainen, J.; Makinen, R.; Torkkeli, M.; Makela, T.; Serimaa, R.; Brinke, G. ten; Ikkala, O. Science 1998, 280, 557-560. 16. Ruokolainen, J.; Brinke, G. ten; Ikkala, O. Adv. Mater. 1999, 11, 777-780. 17. Maki-Ontto, R.; Moel, K.; Odorico, W.; Ruokolainen, J.; Stamm, M.; Brinke, G. trn; Ikkala, O. Adv. Mater. 2001, 13, 117-121. 18. Moel, K.; Ekenstein, G.; Nijland, H.; Polushkin, E.; Brinke, G. ten; Maki-Ontto, R.; Ikkala, O. Chem. Mater. 2001, 13, 4580-4583. 19. Maki-Ontto, R.; Moel, K.; Polushkin, E.; Ekenstein, G.; Brinke, G.ten; Ikkala, O. Adv. Mater. 2002, 14, 357-361. 20. Ikkala, O.; Brinke, G. ten Science 2002, 295, 2407-2409. 21. Dierking, I. “Textures of Liquid Crystals” Wiley-VCH, Weinheim, 1978. 22. Tschierske, C. J. Mater. Chem. 1998, 8(7), 1485-1508. 136 23. Lam, J.; Luo, J.; Dong, Y.; Cheuk, K.; Tang, B. Z. Macromolecules 2002, 35, 8288-8299. 24. Chen, W.; Wunderlich, B. Macromol. Chem. Phys. 1999, 200, 283-311. 25. Tschierske, C. J. Mater. Chem. 1998, 8(7), 1485-1508. 26. Prehm, M.; Diele, S.; Das, M. K.; Tschierske, C. J. Am. Chem. Soc. 2003, 125, 614-615. 27. Tschierske, C. Current Opinion in Colloid & Interface Science 2002, 7, 69-80. 28. Hartikainen, J.; Lahtinen, M.; Torkkeli, M.; Serimaa, R.; Valkonen, J.; Rissanen, K.; Ikkala, O. Macromolecules 2001, 34, 7789-7795. 137 [...]... Figure 4. 8 X-ray diffraction patterns of polymer P1, P1(DBSA)0.5 and P1(DBSA)1.0 130 Table 4. 1 Peak angles (°) and d spacings (Å) for the complexes P1(DBSA)x Polymer 2θ1/° 2θ2/° 2θ3/° 2 4/ ° 2θ5/° d1(Å) d2(Å) d3(Å) d4(Å) d5(Å) 2 .46 2.86 P1(DBSA)0.5 3.02 20.1 P1 4. 91 7 .42 19.8 35.9 30.6 29 .4 17.9 11.9 4. 5 4. 4 The XRD diffraction pattern of P1 shows sharp reflection in the small angle region at 2θ = 2 .46 ,... the number of DBSA molecules per repeating unit of the host polymer 4. 3 Results and Discussion 4. 3.1 FTIR characterization The interaction of the two components in complexes can be investigated using FTIR spectroscopy, where the frequency shifts of the absorption bands of functional groups provide information on the nature and intensity of the interactions Figure 4. 1 shows the FTIR spectra of P1(DBSA)x,... 0.2 g (40 %) 1H NMR (300 MHz, CDCl3, δ ppm): 8.65 - 6.97 (b, ArH, 10 H), 4. 00 (b, -O-CH2-, 2 H), 1.75-1.65 (m, -CH2-, 4 H), 1. 24 (b, -CH2-, 18 H), 0.86 (b, -CH3-, 6 H) FT-IR (KBr, cm-1): 3 041 (ArH stretching), 2958 (-CH2- stretching), 1 745 (ester C=O stretching), 1595, 1 548 , 141 0(Ar, C=C, C=N stretching) 12 74, 1170, 1101 (C-O-C stretching) Mn: 0.62 × 1 04; Mw: 1.16 × 1 04; PD: 1.9 4. 2 .4 Preparation of complexes... 2θ = 2 .46 , 2.86 and 4. 91o, from which d spacings of 35.9 Å, 30.6 Å and 17.9 Å are derived It also offers a sharp reflection in the middle angle region and a broad halo at 2θ = 7 .42 and 19.9 o, from which d spacings of 11.9Å and 4. 5 Å are derived The XRD diffraction pattern of complex P1 (DBSA) 0.5 shows one reflection in the small angle region at 2θ = 3.02 o, from which d spacing of 29 .4 can be calculated,... Further investigation is Intensity (a.u.) needed to explain the results fully x= 1.0 P2 5 10 15 20 25 30 2-theta (degree) Figure 4. 9 X-ray diffraction patterns of polymer P2, and P2(DBSA)1.0 132 Table 4. 2 Peak Angles (°) and d spacing (Å) for the complexes P2(DBSA)1.0 Polymer 2θ1(°) 2θ2(°) 2θ3(°) 2 4( °) 2θ5(°) d1(Å) d2(Å) d3(Å) d4(Å) d5(Å) P2(DBSA)1.0 12.5 P2 16.6 18.9 24. 4 26.1 19.6 7.86 5.93 5.21 4. 04. .. in the self- assembly of the polymer, which helps to pack the polymer chains in ordered structures 24- 27 With the addition of DBSA, the longrange order is difficult to form inside the lattice When the polymers were combined with 131 excess of DBSA, the polar and stabilizing effect of pyrimidine groups is decreased and the side flexible chains in the lateral position interfere with the packing of the... spectra of P2(DBSA)x and the host polymer P2 1 24 Similarly the characteristic peak at 1555 cm - 1of the P2 with pyrimidine groups was observed to shift to 1612 cm –1 with the full complexation and the increase of the peak at around 1190 cm -1 means the increase of the SO3- groups upon deprontonation, which support the formation of the complexes A shift of 57 cm-1 corresponding to the formation of a pyrimidinium... 200 250 o Temperature ( C) Figure 4. 6 DSC traces of the first heating scan for complex P3(DBSA)1.0 and host polymer P3 128 4. 3.3 POM study The novel polymeric complexes P1(DBSA)x were analyzed with polarized optical microscopy to identify the mesophase of the pristine polymer and complexes (shown in Figure 4. 7) When the isotropic liquid of P1 was cooled with a rate of 0.5 °C min-1 to 95 °C, a mosaic... reflection in the small angle is broader than that of host polymer and the reflection in middle angle region is missed, which indicates that the ordered packing decreases compared with that of the host polymer With the increase of the amount of DBSA, and the decrease of the free pyrimidine groups, long-range order disappears In the previous study on the novel jacketed polymer P1 (described in chapter 2 as... Figure 4. 7a) and complex P1(DBSA)0.5 exhibited a typical focal-conic fan texture of smectic A phase 22 when cooled to 78 °C from a isotropic melt (Figure 4. 7b) while no birefringent textures were found from other complexes P1(DBSA)1.0 and P1(DBSA)2.0 during cooling It is well known that the broad polydispersity of polymers will cause hindrance to form mesophase by polymers, which may explain the lack of . CDCl 3 , δ ppm): 171, 149 .80, 149 .45 , 141 .17, 137.08, 136.62, 135.76, 1 34. 62, 1 34. 49, 133.79, 130.59, 129.33, 128.88, 126.63, 1 24. 90, 1 24. 07, 123 .45 , 113.72, 77.33, 76.91, 76 .48 , 69.11, 31.79, 30.79,. = 6 .4 Hz, C(O)-CH 2 -, 2 H), 1.25 (b, -CH 2 - 18 H), 0.87 (t, J = 6.0 Hz, -CH 3 , 3 H). 13 C NMR (75 .4 MHz, CDCl 3 , δ ppm): 150.2, 149 .0, 148 .6, 148 .0, 1 24. 4, 122.0, 117.5, 1 14. 8, 106 .4 (Ar-C),. 3.02. 20.1 29 .4 4 .4 The XRD diffraction pattern of P1 shows sharp reflection in the small angle region at 2θ = 2 .46 , 2.86 and 4. 91 o , from which d spacings of 35.9 Å, 30.6 Å and 17.9 Å are