*2.1.1.2 Preparation of NOBC*

In the course of 25 min, 15 g NOBA was added to 350 ml thionyl chloride, while stirring rapidly at room temperature (4- 4′-(terephthaloyl-diaminedibenzoic chloride)) (NOBC) (II in **Figure 8**). The solution was boiled with the reflux condenser. When the release of HCl ended and most of the sediment had dissolved, the hot solution was filtered and cooled down to 0°C for a day. The obtained product was separated, filtered, vacuum dried and recrystallized in chloroform. Yield is 7.2 g (48%).

## *2.1.1.3 Preparation of PNOBDME*

A mixture of 0.017 mol NOBC and 0.017 mol DL-1,2-dodecanediol was added to 44 ml of diphenyl oxide. Purge with dry nitrogen was used for 25 min at room temperature, and then, while maintaining the gas current, the flask was transferred to a bath containing a high-temperature heat-transfer agent. The polycondensation was carried out for 3 hours and 30 min at 200°C. The reaction finished when the liberation of HCl ended. The result of the polycondensation reaction was poured into 500 ml of toluene, decanting PNOBDME, which was filtered, washed three times with ethanol and vacuum dried. The second fraction of PNOBDME precipitated of the filtrated toluene after 22 weeks was also filtered, washed with ethanol and vacuum dried. Yield first fraction is 2.6 g (25.5%); yield first and second fraction is 3.1 g (30.4%).

**87**

*Cholesteric Liquid Crystal Polyesteramides: Non-Viral Vectors*

*2.1.2 Synthesis of PNOBEE {Poly[oxy(1,2-butylene)-oxy-carbonyl-1,4-phenyleneamine-carbonyl-1,4-phenylene-carbonyl-amine-1,4-phenylene-carbonyl]}:* 

PNOBEE (III in **Figure 9**) was obtained through condensation reaction between (4- 4′-(terephthaloyl-diaminedibenzoic chloride)) (NOBC) (II in **Figure 9**) and the racemic mixture of DL-1,2-butanediol. Notation of cholesteric liquid crystal

NOBC was synthesized by the reaction between NOBA, (4–4′-(terephthaloyldiaminedibenzoic acid)) (NOBA) (I in **Figure 9**), and SOCl2 and recrystallized in chloroform; previously NOBA was obtained by interface condensation between

A mixture of 0.015 mol NOBC and 0.015 mol DL-1,2-butanediol was added to 39 ml of chloronaphthalene. Purge with dry nitrogen was used for 25 min at room temperature, and then, while maintaining the gas current, the flask was transferred to a bath containing a high-temperature heat-transfer agent. The polycondensation was carried out for 180 min at 200°C. The reaction finished when the liberation of HCl ended. The result of the polycondensation reaction was poured into 500 ml of toluene, decanting PNOBEE, which was filtered, washed with ethanol and vacuum dried. The second fraction of PNOBEE precipitated of the filtrated toluene after 22 weeks which was also filtered, washed with ethanol and vacuum dried. Yield is 2.9 g (46.5%).

H-RMN, 13C-NMR,

H-RMN,

*DOI: http://dx.doi.org/10.5772/intechopen.91317*

*(C26H22N2O6)n*

precursor PTOBEE has been used.

*2.1.2.1 Preparation of PNOBEE*

terephthaloyl chloride and 4-aminobenzoic acid.

The structures of NOBA and NOBC were confirmed by <sup>1</sup>

trometers, also at room temperature [31].

*2.1.2.2 Starting materials*

KGaA (Darmstadt, Germany).

**3. Characterization techniques**

Scharlau Chemie.

COSY, TOCSY, NOESY and HSQC registered in DMSO-d6 at 25°C in a Bruker 300 MHz NMR spectrometer. The structure of PNOBDME was studied by 1

13C-NMR, COSY and HSQC, obtained in VARIAN 400 MHz and 500 MHz spec-

Terephthaloyl chloride from Sigma-Aldrich Chemie GmBH (Steinheim, Germany); carbon tetrachloride from Panreac Química (Montcada i Rexach, Barcelona, Spain); NaOH from Panreac Química (Montcada i Rexach, Barcelona, Spain); 4-aminobenzoic acid from Sigma-Aldrich Chemie GmBH (Steinheim, Germany); hydrochloric acid from Normapur VWR International (Fontenay-sous-Bois, France); thionyl chloride from Sigma-Aldrich Chemie GmBH (Steinheim, Germany); chloroform from SDS Votre Partenaire Chimie (Peypin, France); DL-1,2-dodecanediol from Fluka Chemie GmBH (Buchs, Switzerland); diphenyl oxide from Sigma-Aldrich Chemie GmBH (Steinheim, Germany); nitrogen from Praxair (Madrid, Spain); toluene from Merck

DL-1,2-butanediol from Fluka Chemie GmBH (Buchs, Switzerland); chloro-

**Thermal stability** was studied on a Mettler TA4000-TG50 at a heating rate of 10°C/min with nitrogen purge between 30 and 600°C. Thermal behaviour was

naphthalene from Sigma-Aldrich Chemie GmBH (Steinheim, Germany). The solvent used in NMR for all cases was DMSO-d6 from Merck KGaA (Darmstadt, Germany) and DMSO for optical rotatory dispersion (ORD), from *Cholesteric Liquid Crystal Polyesteramides: Non-Viral Vectors DOI: http://dx.doi.org/10.5772/intechopen.91317*

*2.1.2 Synthesis of PNOBEE {Poly[oxy(1,2-butylene)-oxy-carbonyl-1,4-phenyleneamine-carbonyl-1,4-phenylene-carbonyl-amine-1,4-phenylene-carbonyl]}: (C26H22N2O6)n*

PNOBEE (III in **Figure 9**) was obtained through condensation reaction between (4- 4′-(terephthaloyl-diaminedibenzoic chloride)) (NOBC) (II in **Figure 9**) and the racemic mixture of DL-1,2-butanediol. Notation of cholesteric liquid crystal precursor PTOBEE has been used.

NOBC was synthesized by the reaction between NOBA, (4–4′-(terephthaloyldiaminedibenzoic acid)) (NOBA) (I in **Figure 9**), and SOCl2 and recrystallized in chloroform; previously NOBA was obtained by interface condensation between terephthaloyl chloride and 4-aminobenzoic acid.

## *2.1.2.1 Preparation of PNOBEE*

*Liquid Crystals and Display Technology*

scanning calorimetry (DSC) analysis.

*carbonyl]}, (C34H38N2O6)n*

*2.1.1.1 Preparation of NOBA*

comminuted. Yield is 28 g (70%).

*2.1.1.3 Preparation of PNOBDME*

*2.1.1.2 Preparation of NOBC*

**2. Experimental**

**2.1 Materials**

The structure of the polymers so obtained could be confirmed by 1

*2.1.1 Synthesis of PNOBDME {Poly[oxy(1,2-dodecane)-oxy-carbonyl-1,4-*

*phenylene-amine-carbonyl-1,4-phenylene-carbonyl-amine-1,4-phenylene-*

PNOBDME (III in **Figure 8**) was obtained through condensation reaction between 4, 4′-(terephthaloyl-diaminedibenzoic chloride) (NOBC) (II in **Figure 8**) and the racemic mixture of DL-1,2-dodecanediol. Similar notation to precursor cholesteric liquid crystal PTOBDME [16, 17] obtained by a similar method has been used.

Solutions of 0.1 mol terephthaloyl chloride in 200 ml carbon tetrachloride and 0.2 mol NaOH in water were added while stirring at room temperature for 15 min to a solution of 0.22 mol of 4-aminobenzoic acid and 0.2 mol NaOH in 400 ml water (Milli-Q grade) (4–4′-(terephthaloyl-diaminedibenzoic acid)) (NOBA), (I in **Figure 8**). Stirring was continued for 12 hours. Sediment was separated, filtered, washed several times with 40 ml of cold water, dried, comminuted and transferred to a vessel where it was mixed for 3 hours with 300 ml of hydrochloric acid. The product was filtered, washed several times with 40 ml of cold water, dried and

In the course of 25 min, 15 g NOBA was added to 350 ml thionyl chloride, while stirring rapidly at room temperature (4- 4′-(terephthaloyl-diaminedibenzoic chloride)) (NOBC) (II in **Figure 8**). The solution was boiled with the reflux condenser. When the release of HCl ended and most of the sediment had dissolved, the hot solution was filtered and cooled down to 0°C for a day. The obtained product was separated, filtered, vacuum dried and recrystallized in chloroform. Yield is 7.2 g (48%).

A mixture of 0.017 mol NOBC and 0.017 mol DL-1,2-dodecanediol was added to 44 ml of diphenyl oxide. Purge with dry nitrogen was used for 25 min at room temperature, and then, while maintaining the gas current, the flask was transferred to a bath containing a high-temperature heat-transfer agent. The polycondensation was carried out for 3 hours and 30 min at 200°C. The reaction finished when the liberation of HCl ended. The result of the polycondensation reaction was poured into 500 ml of toluene, decanting PNOBDME, which was filtered, washed three times with ethanol and vacuum dried. The second fraction of PNOBDME precipitated of the filtrated toluene after 22 weeks was also filtered, washed with ethanol and vacuum dried. Yield first fraction is 2.6 g (25.5%); yield first and second frac-

HSQC NMR [31]. The NMR shifts were assigned according to our previous notation. Their thermal stability is studied by thermogravimetric (TG) and differential

H, 13C, COSY and

**86**

tion is 3.1 g (30.4%).

A mixture of 0.015 mol NOBC and 0.015 mol DL-1,2-butanediol was added to 39 ml of chloronaphthalene. Purge with dry nitrogen was used for 25 min at room temperature, and then, while maintaining the gas current, the flask was transferred to a bath containing a high-temperature heat-transfer agent. The polycondensation was carried out for 180 min at 200°C. The reaction finished when the liberation of HCl ended. The result of the polycondensation reaction was poured into 500 ml of toluene, decanting PNOBEE, which was filtered, washed with ethanol and vacuum dried. The second fraction of PNOBEE precipitated of the filtrated toluene after 22 weeks which was also filtered, washed with ethanol and vacuum dried. Yield is 2.9 g (46.5%).

The structures of NOBA and NOBC were confirmed by <sup>1</sup> H-RMN, 13C-NMR, COSY, TOCSY, NOESY and HSQC registered in DMSO-d6 at 25°C in a Bruker 300 MHz NMR spectrometer. The structure of PNOBDME was studied by 1 H-RMN, 13C-NMR, COSY and HSQC, obtained in VARIAN 400 MHz and 500 MHz spectrometers, also at room temperature [31].

#### *2.1.2.2 Starting materials*

Terephthaloyl chloride from Sigma-Aldrich Chemie GmBH (Steinheim, Germany); carbon tetrachloride from Panreac Química (Montcada i Rexach, Barcelona, Spain); NaOH from Panreac Química (Montcada i Rexach, Barcelona, Spain); 4-aminobenzoic acid from Sigma-Aldrich Chemie GmBH (Steinheim, Germany); hydrochloric acid from Normapur VWR International (Fontenay-sous-Bois, France); thionyl chloride from Sigma-Aldrich Chemie GmBH (Steinheim, Germany); chloroform from SDS Votre Partenaire Chimie (Peypin, France); DL-1,2-dodecanediol from Fluka Chemie GmBH (Buchs, Switzerland); diphenyl oxide from Sigma-Aldrich Chemie GmBH (Steinheim, Germany); nitrogen from Praxair (Madrid, Spain); toluene from Merck KGaA (Darmstadt, Germany).

DL-1,2-butanediol from Fluka Chemie GmBH (Buchs, Switzerland); chloronaphthalene from Sigma-Aldrich Chemie GmBH (Steinheim, Germany).

The solvent used in NMR for all cases was DMSO-d6 from Merck KGaA (Darmstadt, Germany) and DMSO for optical rotatory dispersion (ORD), from Scharlau Chemie.

### **3. Characterization techniques**

**Thermal stability** was studied on a Mettler TA4000-TG50 at a heating rate of 10°C/min with nitrogen purge between 30 and 600°C. Thermal behaviour was

analyzed by DSC in a Mettler TA4000/DSC30/TC11 calorimeter, with a series of heating/cooling cycles in a temperature range between 0 and 230°C.

**Microcalorimetry** was estimated in a MicroCal Inc., model MCS-DSC, within a range of temperature 4–120°C, at a heating rate of 10–20°C/h, and a volume of sample 1.5 ml.

**Optical rotatory dispersion** was measured in a Perkin Elmer 241 MC polarimeter, at 25°C in DMSO. Conditions used: λNa = 589 nm, slit = 5 mm, integration time = 50 s; λHg = 574 nm, slit = 14 mm, integration time = 50 s; λHg = 546 nm, slit = 30 mm, integration time = 50 s; λHg = 435 nm, slit = 5 mm, integration time = 50 s; and λHg = 365 nm, slit = 2.5 mm, integration time = 50 s.

**Morphology** was evaluated in an environmental scanning electron microscope (ESEM), PHILIPS XL30.

**Simultaneous SAXS/WAXS** of PNOBDME were performed at 16.1.1 beamline of the synchrotron radiation source (SRS) at Daresbury Laboratory, Warrington, UK, with a monochromatized beam (λ = 1.4 Å). Both WAXS and SAXS detectors were lineal. HDPE was used to calibrate the WAXS data and wet collagen (rat tail tendon, d = 676.08 Å) to calibrate the *q*-axis of the SAXS detector (*q = 4π sin θ∕λ*), where the scattering angle is defined by *2θ*. The experimental data were corrected for background scattering, sample absorption and positional lack of linearity of the detector, with the help of ATSAS [23, 24]. The samples dispersed in dichloromethane solution were applied dropwise on the sample holder and the solvent let to evaporate.

#### **3.1 Thermal behaviour of PNOBDME and PNOBEE**

**Figure 10(a)** shows the thermogravimetric curve of polyesteramide PNOBDME first fraction. A 5 and 10% weight loss is observed, respectively, at 282 and 310.3*°*C, increasing the thermal stability range of precursor polyester PTOBDME, with 10% weight loss percentage at 280°C [16].

In **Figure 10(b)**, the PNOBEE thermal stability can be observed. A 10% weight loss is registered at 330°C, due to thermal decomposition, a value higher than those observed for PTOBEE (280°C) [11] and PNOBDME (310.3°C). The entrance of the amide group in the mesogen causes an increase of thermal stability with respect to PTOBEE.

In **Figure 11(a)**, the DSC analysis of PNOBDME first fraction is exhibited and its Microcalorimetry curve appears in **Figure 11(b)**.

During the first heating run of the DSC of PNOBDME, performed at 10°C/min rate, **Figure 11(a)**, a glass transition around 62.5°C is observed, together with a

#### **Figure 10.**

*(a) Thermogravimetric curve of PNOBDME first fraction; (b) thermogravimetric curve of PNOBEE first fraction.*

**89**

**Figure 12.**

*down; (c) second heating run.*

188.3°C.

**Figure 11.**

by microcalorimetry, **Figure 11(b)**.

increasing the stability range.

*Cholesteric Liquid Crystal Polyesteramides: Non-Viral Vectors*

small broad endothermic peak centred at 156°C. During the cooling, an exothermic peak at 183°C is indicative of crystallization from the mesophase, a higher value than that of PTOBDME (149°C). In the second heating, a glass transition is observed around 71.6°C and two broad and small endothermic peaks at 108.7 and

*(a) DSC analysis of PNOBDME first fraction; (b) microcalorimetry of PNOBDME.*

Subsequently, PNOBDME was heated up to 230°C, at 10°C/min, cooled to 190°C and isothermally heated for 2 hours, then cooled to 30°C at 10°C/min and finally heated again to 230°C, at 10°C/min. Although the isothermal treatment at 190°C, after cooling from 230°C, should have produced an induced crystallization process (endothermic peak due to the polymer transition to mesophase), only a small endothermic peak at 109°C is observed not caused by the isothermal cooling. The endothermic transition from crystal to mesophase was also confirmed at 109°C

The DSC curve of PNOBEE is shown in **Figure 12**. During the first heating run (a), at a 10°C/min rate, a glass transition around 55°C is observed. A very broad endothermic peak centred at 185.3°C is interpreted as a fusion associated with a transition from crystal to liquid crystal. Another endothermic peak at 233.7°C is observed near the beginning of thermal decomposition. In the cooling run (b), two small exothermic peaks observed at 205.6 and 183.0°C are interpreted as crystallization processes

from the mesophase. In the second heating (c), no transition is observed.

Compared to PTOBEE, with a transition to mesophase at 150°C and with exothermic crystal formation at 110°C during isothermal heating, a remarkable difference is observed by the substitution of ester groups by amide in the mesogen,

*DSC analysis of PNOBEE first fraction. (a) First heating run of the original sample; (b) subsequent cooling* 

*DOI: http://dx.doi.org/10.5772/intechopen.91317*

**Figure 11.**

*Liquid Crystals and Display Technology*

sample 1.5 ml.

(ESEM), PHILIPS XL30.

holder and the solvent let to evaporate.

weight loss percentage at 280°C [16].

**3.1 Thermal behaviour of PNOBDME and PNOBEE**

its Microcalorimetry curve appears in **Figure 11(b)**.

analyzed by DSC in a Mettler TA4000/DSC30/TC11 calorimeter, with a series of

**Microcalorimetry** was estimated in a MicroCal Inc., model MCS-DSC, within a range of temperature 4–120°C, at a heating rate of 10–20°C/h, and a volume of

**Optical rotatory dispersion** was measured in a Perkin Elmer 241 MC polarimeter, at 25°C in DMSO. Conditions used: λNa = 589 nm, slit = 5 mm, integration time = 50 s; λHg = 574 nm, slit = 14 mm, integration time = 50 s; λHg = 546 nm, slit = 30 mm, integration time = 50 s; λHg = 435 nm, slit = 5 mm, integration

**Morphology** was evaluated in an environmental scanning electron microscope

**Figure 10(a)** shows the thermogravimetric curve of polyesteramide PNOBDME first fraction. A 5 and 10% weight loss is observed, respectively, at 282 and 310.3*°*C, increasing the thermal stability range of precursor polyester PTOBDME, with 10%

In **Figure 10(b)**, the PNOBEE thermal stability can be observed. A 10% weight loss is registered at 330°C, due to thermal decomposition, a value higher than those observed for PTOBEE (280°C) [11] and PNOBDME (310.3°C). The entrance of the amide group in the mesogen causes an increase of thermal stability with respect to

In **Figure 11(a)**, the DSC analysis of PNOBDME first fraction is exhibited and

During the first heating run of the DSC of PNOBDME, performed at 10°C/min rate, **Figure 11(a)**, a glass transition around 62.5°C is observed, together with a

*(a) Thermogravimetric curve of PNOBDME first fraction; (b) thermogravimetric curve of PNOBEE first* 

**Simultaneous SAXS/WAXS** of PNOBDME were performed at 16.1.1 beamline of the synchrotron radiation source (SRS) at Daresbury Laboratory, Warrington, UK, with a monochromatized beam (λ = 1.4 Å). Both WAXS and SAXS detectors were lineal. HDPE was used to calibrate the WAXS data and wet collagen (rat tail tendon, d = 676.08 Å) to calibrate the *q*-axis of the SAXS detector (*q = 4π sin θ∕λ*), where the scattering angle is defined by *2θ*. The experimental data were corrected for background scattering, sample absorption and positional lack of linearity of the detector, with the help of ATSAS [23, 24]. The samples dispersed in dichloromethane solution were applied dropwise on the sample

heating/cooling cycles in a temperature range between 0 and 230°C.

time = 50 s; and λHg = 365 nm, slit = 2.5 mm, integration time = 50 s.

**88**

**Figure 10.**

*fraction.*

PTOBEE.

*(a) DSC analysis of PNOBDME first fraction; (b) microcalorimetry of PNOBDME.*

small broad endothermic peak centred at 156°C. During the cooling, an exothermic peak at 183°C is indicative of crystallization from the mesophase, a higher value than that of PTOBDME (149°C). In the second heating, a glass transition is observed around 71.6°C and two broad and small endothermic peaks at 108.7 and 188.3°C.

Subsequently, PNOBDME was heated up to 230°C, at 10°C/min, cooled to 190°C and isothermally heated for 2 hours, then cooled to 30°C at 10°C/min and finally heated again to 230°C, at 10°C/min. Although the isothermal treatment at 190°C, after cooling from 230°C, should have produced an induced crystallization process (endothermic peak due to the polymer transition to mesophase), only a small endothermic peak at 109°C is observed not caused by the isothermal cooling. The endothermic transition from crystal to mesophase was also confirmed at 109°C by microcalorimetry, **Figure 11(b)**.

The DSC curve of PNOBEE is shown in **Figure 12**. During the first heating run (a), at a 10°C/min rate, a glass transition around 55°C is observed. A very broad endothermic peak centred at 185.3°C is interpreted as a fusion associated with a transition from crystal to liquid crystal. Another endothermic peak at 233.7°C is observed near the beginning of thermal decomposition. In the cooling run (b), two small exothermic peaks observed at 205.6 and 183.0°C are interpreted as crystallization processes from the mesophase. In the second heating (c), no transition is observed.

Compared to PTOBEE, with a transition to mesophase at 150°C and with exothermic crystal formation at 110°C during isothermal heating, a remarkable difference is observed by the substitution of ester groups by amide in the mesogen, increasing the stability range.

#### **Figure 12.**

*DSC analysis of PNOBEE first fraction. (a) First heating run of the original sample; (b) subsequent cooling down; (c) second heating run.*
