Synthesis and characterization of novel jacketed polymers and investigation of their self assembly and application 2

After finishing the addition, the reaction mixture was stirred for 18 h, allowed to cool to RT and then filtered.. The reaction mixture was allowed to cool to RT, filtered, concentrated

Chapter 2 Part 2 Synthesis, characterization of a series of novel mesogen- jacketed polymers and investigation of their self-

assembly properties

2.2.1 Introduction

Based on the previous results, the alkyl chains in the lateral position on the mesogenic core exert a great negative effect on the self-assembly of the jacketed polymers To overcome this disadvantage, two methods were proposed: one involves shorter alkyl chain to decrease this disturbance; and introduction of polar groups to increase the incompatibility and stability to the microphase separation

We report the synthesis of a series of novel jacketed polymers Strong electrostatic, weak Van der Wall’s interaction and geometrical effects were incorporated in the substituents attached to the polymer backbone to control the self-assembly of polymer chains in the lattice The novel polymers were characterized using GPC, DSC, TGA, FTIR, and NMR The morphology of these polymers on the substrate was studied via AFM, polar optical micrograph This work shows some characterization about the rigid side chain organization and may provide a new method for designing some supramolecular building blocks to control synthetic polymer function, size and shape

2.2.2 Experimental section

2.2.2.1 Materials and reagents

All reagents and solvents were obtained from commercial sources 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 silica gel (60-mesh, Aldrich) Dibenzoyl peroxide (BPO) was recrystallized from

chloroform-methanol solution as glistening crystals, and used as initiators for

polymerization

2.2.2.2 Instrumentation

1 H NMR, 13C NMR spectra were recorded on a Bruker ACF 300 MHz spectrometer.MS spectra were obtained using a Finnigan TSQ 7000 spectrometer with ESI or EI ionization capabilities Data from thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) thermograms 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 an X-ray powder diffractometer with a graphite monochromator using

Cu Kα radiator with a wavelength of 1.54 Å at room temperature (scanning rate: 0.05 o/s; scan range 1.5 - 30 o) A Zeiss Axiolab polarized optical microscopy (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 pyramidal Si3N4 probes (25 °C, in air) All films were spin-coated from polymer solutions in THF (0.5 mg/ml) onto glass slide at 2000 rpm for 3 min

2.2.2.3 Synthesis

Poly (5’-methoxy [1, 1', 4', 4"] terphenyl-2-yl methacrylate) (P01),

poly(1,3-bis(5’-methoxy [1, 1’, 4’, 1”] terphenyl -2’-yloxy)-2-propyl methacrylate) (P02), poly

(5-dodecyloxy [1, 1’, 4’, 1”] terphenyl -2-yl methacrylate) (P03), and poly (4-(5-dodecyloxy-

(4-dodecyloxy-2,5-bis(pyrimidin-5-yl)-phenyl-1-yl methacrylate) (P04) were synthesized using the route

shown in Scheme 2.2.1 and Scheme 2.2.2:

OH

OH

Br Br

BrOBn

OH

OBn

Br Br

K2CO3/DMF

CH3I NaOH/EtOH

OCH3

OBn

Br Br

Pd(PPh3)4/Toluene/EtOH 2M Na 2 CO 3

N

N N

OC12H25n

O O

OC12H25n

Scheme 2.2.2 Synthetic route for polymers P 03 and P 04

4-Benzyloxy-2, 5-dibromophenol (2)

In a 250 ml round-bottom flask with a stir bar was placed 13.4 g of 1 (0.1 mol), 10.4 g

K2CO3 (0.075 mol) and 150 ml dry DMF The mixture was purged with N2 for 20 min, heated to 60 - 70 °C under nitrogen atmosphere A solution of benzyl bromide 5.6 ml (0.05 mol) in 10 ml absolute ethanol was added dropwise After finishing the addition, the reaction mixture was stirred for 18 h, allowed to cool to RT and then filtered The solution was concentrated and poured into water The pH was adjusted to about 6 The obtained precipitate was recrystalized in ethanol to yield a white powder Yield: 5.75g (77.9 %) 1H NMR (300 MHz, CDCl3, δ ppm) 10.2 (s, OH, 1H), 7.5-7.1, (m, ArH, 7H), 5.2 (s, Ar-CH2-O, 2H) 13C NMR (75.4 MHz, CDCl3, δ ppm) 159.9, 136.9, 135.7, 128.4, 127.6, 113.7 (ArC), 68.8 (O-CH2-Ar) MS (ESI): m/z: 357.9, 267.9, 91.1 Mp: 108 °C

1-Benzyloxy-2, 5-dibromo-4-methoxy benzene (3)

5.37 g of 2 (0.015 mol), and 100 ml absolute ethanol were added to a 250 ml

round-bottom flask, and purged with N2 for 20 min 0.9 g NaOH was added to the mixture and purged with N2 for another 20 min, heated to 60 °C and 15 ml 2M iodomethane in hexane (0.03 mol) was added dropwise to the solution After finishing the addition, the reaction mixture was kept stirring for overnight under N2 atmosphere The reaction mixture was allowed to cool to RT, filtered, concentrated and poured into water The precipitate was recrystalized from methanol to yield a white powder Yield: 5.4 g (96.7 %) 1H NMR (300 MHz, DMSO, δ ppm) 7.5-7.3 (m, ArH, 7H) 5.16 (s, O-CH2-Ar, 2H), 3.8 (s, O-CH3, 3H)

13C NMR (75.4 MHz, DMSO δ ppm) 150.2, 148.9, 136.4, 128.4, 127.9, 127.4, 118.8, 116.9, 110.8, 109.7 (Ar-C), 70.9 (O-CH2-Ar), 56.8 (O-CH3) MS (ESI): m/z: 371.9,

281.9, 91.1 Mp: 106 °C

5’-benzyloxy-2’-methoxy [1, 1’; 4’, 1”] terphenyl (4) 1

A 250 ml round-bottom flask equipped with a condenser was charged with compound 3

(5.58 g, 15 mmol), 5.50 g phenyl boronic acid (45 mmol), 80 ml toluene, 20 ml methanol and 80 ml 2M sodium carbonate solution The mixture was degassed via 3 cycles, before the catalyst of 0.2g tetrakis (triphenylphosphine) palladium (5 mol%) was added in dark under argon atmosphere The reaction mixture was heated at 100 °C for 48 h, before being allowed to cool to RT and then filtered The liquid layer was separated with a separation funnel, and the aqueous layer was extracted with 2 × 100 ml toluene The toluene layer was combined, washed with 3× 100 ml water and dried over MgSO4 The solvent was then removed with a rotary evaporator, and the resulting crude product was purified using column chromatography on a silica gel column with hexane and dichloromethane (4:1) as the eluant Yield: 4.6 g (44.3%) 1H NMR (300 MHz, DMSO-d6,

δ ppm) 7.64-7.33 (m, ArH, 15 H) 7.12 (s, ArH, 1 H), 7.04 (s, ArH, 1 H), 5.10 (s, O-CH2

-Ar, 2 H), 3.76 (s, O-CH3, 3 H) 13C NMR (75.4 MHz, DMSO, δ ppm) 150.4, 137.8, 129.3, 129.2, 128.2, 128.0, 127.5, 127.1, 126.9, 116.4, 114.4 (Ar-C), 70.4 (O-CH2-Ar), 58.2 (O-

CH3) MS (ESI): m/z: 366.2, 275.1, 260.1, 244.1, 202.0, 198.0, 91.1 Mp: 100 °C

5’-Methoxy [1, 1’; 4’, 1”] terphenyl-2’-ol (5)

To a 100 ml round-bottomed flask containing 10 % Pd/C (2.5 g) in 50 ml THF was added

compound 4 (4.40 g, 5 mmol), charged with nitrogen, and a balloon filled with H2 was fitted to the flask The nitrogen 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 phases were combined and

the solvent was removed under reduced pressure to yield a white powder The resulting crude product was purified by column chromatography on a silica gel column using hexane and ethyl acetate (1:4) as the eluent Yield: 3.2 g (96.4 %) 1H NMR (300 MHz, CDCl3, δ ppm) 7.54 - 7.43 (m, ArH, 10 H) 7.00 (s, ArH, 1 H), 6.88 (s, ArH, 1 H), 5.0 (b, Ar-OH, 1 H), 3.77 (s, O-CH3, 3 H) 13C NMR (75.4 MHz, CDCl3, δ ppm) 154.6, 135.5, 128.1, 122.8, 128.2, 128.0, 127.5, 116.4, 114.4 (Ar-C), 18.3 (O-CH3) MS (ESI): m/z: 276.2, 261.1, 200.0, 185.1, 157.1, 128.1, 84.0 Mp: 127.5 °C

5-Methoxy [1, 1’; 4’, 1”] terphenyl-2-yl methacrylate (6)

A 100 ml round bottom flask was charged with triethylamine (3.1 ml, 19.5 mmol),

compound 5 (1.8 g, 6.5 mmol) and 30 ml dry THF This solution was cooled to 0 °C, and

added with a solution of methacryloyl chloride (1.3 ml, 13 mmol) in 4 ml THF After finishing the addition, the reaction mixture was warmed to room temperature and stirred for 4 hr The mixture was then 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 to yield the monomer Yield: 1.23g (93%) 1H NMR (300 MHz, CDCl3, δ ppm) 7.59 - 7.00 (m, ArH, 12 H), 6.1 (s, CH2=C, 1 H), 5.6 (s, CH2=C, 1 H), 3.84 (s, O-CH3, 3 H), 1.9 (s, =C-CH3, 3 H) 13C NMR (75.4 MHz, CDCl3, δ ppm) 166.5 (C=O), 153.1, 137.5, 135.6, 129.5, 128.8, 128.2, 127.4, 126.8, 124.8, 114.5, 113.3 (Ar-C, C=C), 58.9 (O-CH3), 18.4 (=C-CH3) MS (EI): m/z: 344.2, 303.2, 275.2, 260.2, 215.2 Mp: 82 °C

1, 3-Bis (5-methoxy [1, 1’; 4, 1”] terphenyl-2-yloxy) propan-2-ol (7)

To a 250 ml three neck round bottom flask fitted with a reflux condenser, addition funnel

and a nitrogen inlet were added 100 ml DMF, compound 5 (2.76 g, 10 mmol) and

potassium carbonate (2.8 g, 20 mmol) The mixture was purged with N2 for 30 min then stirred at 80 °C for 1 hr under nitrogen atmosphere A solution of 1,3-dibromo-2-propanol (0.41 ml, 4.0 mmol) in 5 ml DMF was added dropwise using a dropping funnel The reaction mixture was stirred at 80 °C for 12 hr and filtered The volatile components were removed under reduced pressure and excessive phenol was removed by washing with 2M sodium hydroxide and water (3 × 100 ml) The resulting crude product was purified using column chromatography on a silica gel column with hexane and dichloromethane (2:1) as the eluent Yield: 1.2 g (49.2 %) 1H NMR (300 MHz, CDCl3, δ ppm) 7.60-6.96 (m, ArH, 20 H), 4.1 (p, J= 5.1 Hz, C-CH(O)-C, 1H), 3.94 (d, J= 4.8 Hz, O-CH2-C, 4 H), 3.82 (s, O-CH3), 2.17 (b, C-OH) 13C NMR (75.4 MHz, CDCl3, δ ppm) 151.2, 149.4, 138.1, 131.3, 130.6, 130.5, 129.4, 128.1, 126.2, 118.2, 117.2, 116.2, 115., 114.5, 114.3, 113.2 (Ar-C), 70.7 (Ar-O-CH2-), 68.6 (HO-CH(C)-), 57.2 (O-CH3) MS (EI): m/z: 608.3, 332.2, 276.2, 261.2, 215.1 Mp: 79 °C

1, 3-Bis (5’-methoxy [1, 1’; 4’, 1”] terphenyl-2’-yloxy)-2-propyl methacrylate (8)

Compound 8 was synthesized according to the procedure described for the synthesis of compound 6 Yield: 1.6 g (72.0%) 1H NMR (300 MHz, CDCl3, δ ppm) 7.56 - 6.85 (m, ArH, 24 H), 6.29 (s, CH2=C, 1 H), 5.8 (s, CH2=C, 1 H), 5.3 (p, J= 6.7 Hz, O-CH(C)-C, 1 H,), 4.05 (d, J= 4.2 Hz, O-CH2-C, 4 H), 3.8 (s, O-CH3, 6 H), 1.9 (s, =C-CH3, 3 H) 13C NMR (75.4 MHz, CDCl3, δ ppm) 160.5 (C=O), 151.1, 149.4, 137.9, 131.3, 129.4, 127.8,

127.1, 116.7, 114.4, 112.9 (Ar-C, C=C), 70.7 (COO-C), 67.6 (Ar-O-C), 56.3 (O-CH3) 18.4 (=C-CH3) MS (EI): m/z: 676.2, 620.2, 564.3, 387.4, 315.2, 300.2, 260.2, 215.2 Mp:

78 °C

Poly(5’-methoxy [1, 1'; 4’, 1"] terphenyl-2-yl methacrylate) (P01)

A 25 ml round flask was charged with 1.0 g of compound 6, 0.01 g (1 wt%) of BPO, 2 ml

THF and sealed with a rubber septum The solution was subjected to freeze-pump-thaw cycles, and stirred at 70 °C for 48 h under N2 atmosphere The crude reaction mixture was precipitated in MeOH The resulted solid was dissolved in THF, re-precipitated in methanol several times and dried under high vacuum Yield: 0.8 g (80%) 1H NMR (300 MHz, CDCl3, δ ppm) 7.48 - 7.39 (b, ArH, 12 H), 3.84 -3.76 (b, O-CH3, 3 H), 1.27 (b, -

CH2-, 2 H), 0.92 (b, -CH3, 3 H) FT-IR (KBr, cm-1): 3055 (ArH stretching), 2930 (-CH2- stretching), 1743 (ester C=O stretching), 1601,1514,1479 (Ar, C=C stretching), 1250,

1725 (ester C=O stretching), 1599, 1514, 1481 (Ar, C=C stretching), 1259, 1183, 1058 (C-O-C stretching) Mw: 1.62 × 104, Mn: 1.02 × 104, PD: 1.6

2-Benzyloxy-5-dodecyloxy phenyl-1, 4-diboronic acid (11)

10 g of compound 10 and 150 ml dry THF were placed in a round-bottom flask The

solution was cooled to -78 °C and 55 ml (0.088 mol) of a 1.6 M solution of butyl lithium

in hexanes were added slowly under a nitrogen atmosphere The solution was warmed to

RT and re-cooled to -78 °C, followed by the dropwise addition of triisopropylborate (51 ml) during a period of 2 h After complete addition, the mixture was warmed to RT, stirred overnight, and mixed with 2 L of deionized water The organic phase was collected, dried with MgSO4, and filtered The excess solvent was removed under reduced pressure, and the crude product was re-crystallized from acetone Yield: 5.7 g (80.0%) 1H NMR (300 MHz, DMSO, δ ppm) 7.52 (s, Ar-B(OH)2, 2 H), 7.40(s, Ar-B(OH)2, 2 H), 7.40-7.17 (m, ArH, 7 H), 5.11 (s, Ar-CH2-O, 2 H), 4.00 (t, J = 4.8, O-CH2-

C, 2 H), 1.73 (q, J = 6.4 Hz, C(O)-CH2-, 2 H), 1.24 (b, -CH2-, 16 H), 0.85 (t, J = 6.84 Hz, -CH3, 3 H) 13C NMR (75.4 MHz, CDCl3, δ ppm) 151.5, 145.7, 144.6, 130.7, 126.4, 126.3, 123.4, 121.9, 120.4, 119.7, 111.8, 110.7, 110.5, 109.4 (Ar-C), 66.5 (O-CH2-Ar), 66.2 (O-CH2-), 26.6, 24., 24.2, 24.1, 24.0, 23.9, 23.8, 20.7, 17.4, 8.8 (alkyl C) MS (ESI): m/z: 368.1, 277.1, 200.0, 109.0 Mp: 115 °C

1-Benzyloxy-4-dodecyloxy-2, 5-di (pyrimidin-5-yl) benzene (12)

Compound 12 was synthesized according to the procedure described for the synthesis of compound 4 From 5.2 g (14.1 mmol) of compound 11 and 5.5 g (34.6 mmol) of 5-

bromopyrimidine was obtained the deserved molecule as white powder Yield: 4.5 g (60.8%) 1H NMR (300 MHz, CDCl3, δ ppm): 9.18 - 8.91 (m, Ar-H, 6 H), 7.32 - 7.26 (m, ArH, 5 H), 7.06 (s, ArH, 1 H), 6.98 (s, ArH, 1 H), 5.09 (s, O-CH2-Ar, 2 H), 3.98 (t, J = 6.3 Hz, O-CH2-, 2 H), 1.73 (p, J = 7.5 Hz, R(O)-CH2-, 2 H), 1.26 (b, -CH2- 18 H), 0.87 (t,

J = 6.7 Hz, -CH3, 3 H) 13C NMR (75.4 MHz, CDCl3, δ ppm): 157.0, 156.7, 150.8, 149.5,

131.5, 128.6, 128.2, 127.2, 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-), 13.9 (-CH3) MS (ESI): m/z: 524.5, 433.4, 355.2, 265.1, 238.1, 91.1 Mp: 132 °C

4-Dodecyloxy-2, 5-di(pyrimidin-5-yl) phenol (13)

Compound 13 was synthesized according to the procedure described for the synthesis of compound 5 Yield: 2.5 g (88.7 %) 1H NMR (300MHz, DMSO, δ ppm): 9.82 (s, Ar-OH,

1 H), 9.15 - 8.94 (m, Ar-H, 6 H), 7.25 (s, ArH, 1 H), 7.03 (s, ArH, 1 H), 4.04 (t, J = 6.3

Hz, O-CH2-, 2 H), 1.62 (p, J = 6.4 Hz, R(O)-CH2-, 2 H), 1.26 (b, -CH2- 18 H), 0.87 (t, J = 6.0 Hz, -CH3, 3 H) 13C NMR (75.4 MHz, CDCl3, δ ppm): 156.5, 156.3, 149.0, 148.6, 131.5, 131.4 131.2, 124.4, 122.0, 117.5, 114.8, 106.4, 92.4 (Ar-C), 68.8 (O-CH-), 31.2, 28.9, 28.8, 28.7, 28.6, 28.5, 28.4, 25.4, 21.9 20.2 (-CH2-), 13.8 (-CH3) MS (ESI): m/z: 434.3, 226.1, 238.1, 212.1, 158.1, 106.1, 71.1, 57.1 Mp: 170 °C

4-Dodecyloxy-2, 5-di(pyrimidin-5-yl) phenyl-1-yl methacrylate (14)

Compound 14 was synthesized according to the procedure described for the synthesis of compound 6 From the reaction of 2.0 g (4.6mmol) of compound 13 and 1.5 ml (11 mmol) methacryloyl chloride was obtained the desired monomer 14 as light yellow powder

Yield: 0.9 g (38.9%) 1H NMR (300 MHz, CDCl3, δ ppm): 9.22 - 8.87 (m, Ar-H, 6 H), 7.26 (s, ArH, 1 H), 7.04(s, ArH, 1H), 6.22 (s, CH2=C, 1 H), 5.71 (s, CH2=C, 1 H), 4.04 (t,

J = 6.6 Hz, O-CH2-C, 2 H), 1.93 (s, =C-CH3, 3H), 1.74 (p, J = 6.7 Hz, R(O)-CH2-, 2 H), 1.24 (b, -CH2- 18 H), 0.89 (t, J = 7.2 Hz, -CH3, 3 H) 13C NMR (75.4 MHz, CDCl3, δ ppm): 157.9 (C=O), 157.3, 156.7, 156.2, 154.2, 141.5, 134.8, 129.1, 128.2, 125.2, 124.8, 113.5 (ArC, C=C), 69.3 (O-CH-), 31.8, 29.5, 29.4, 29.3, 29.2, 29.1, 28.7, 27.9, 25.8, 22.6