Preparation of Poly(Oxybiphenyleneoxy-2,5-Dihexyloxyterephthaloyl)
(OBDT) Nanocomposites
Diethyl-2,5-dihexyloxyterephthalic acid was synthesized via a multistep route, and
4,4
0 -biphenol was purchased from Aldrich Chemical Co. The polyester-based poly
(oxybiphenyleneoxy-2,5-dihexyloxyterephthaloyl) (OBDT) nanocomposite was
prepared by in situ polycondensation of equivalent weights of diethyl-2,5dihexyloxyterephthaloyl chloride and 4,4
0 -biphenol in the presence of C18-MMT.
Because the synthetic procedures for the C18-MMT/OBDT nanocomposites with
various organoclay contents are very similar, only the preparation of the 3 wt%
C18-MMT/OBDT is described here. TCE/pyridine (v/v = 50/50) (100 mL)
mixed solvent and C18-MMT (0.45 g) were placed in a polymerization tube, and
the mixture was stirred for 24 h at room temperature. Diethyl-2,5-dihexyloxyterephthaloyl chloride was obtained from diethyl-2,5-dihexyloxyterephthalic
acid and SOCl 2 following a method in the literature. Diethyl-2,5dihexyloxyterephthalic acid (20.0 g, 5.4 Â 10
À1 mol) was dissolved in SOCl 2 , and
the solution was refluxed for 12 h, after which the excess SOCl 2 was removed by
distillation at room temperature under vacuum. In a separate tube, 10.85 g (27 mmol)
of diethyl-2,5-dihexyloxyterephthaloyl chloride was added to TCE (100 mL), and
this mixture was added to the organoclay/pyridine solution and 5.1 g (27 mmol) of
4,4
0 -biphenol/pyridine solution, with vigorous stirring to obtain a homogeneously
dispersed system. This mixture was heated for 10 h at 100
C under a steady stream
of N 2 gas. The product was cooled to room temperature and poured into methanol.
The precipitated product was repeatedly washed with methanol and water, and dried
under vacuum at 80
C for 12 h to obtain the polyester-based OBDT nanocomposites. The chemical structure of OBDT is shown in Scheme 1. The synthetic
route for OBDT nanocomposite is shown in Scheme 3.
The polymers are soluble in mixed solvents; therefore, the solvent mixture
p-chlorophenol/TCE (w/w = 50/50) was used in the solution viscosity measurement.
The solution viscosity values (see Table 2) were found to range from 0.55 to 0.82.
These viscosity numbers can be regarded as constant except for that for the 7 wt%
C18-MMT/OBDT hybrid. In this hybrid, excess organoclay seems to prohibit
production of the higher-molecular-weight polymer.
Preparation of Polyazomethine (PAM) Nanocomposites
PAM was prepared by direct polycondensation of equivalent weights of
2,5-diaminotoluene and terephthaldicarboxyaldehyde in ethanol. The chemical
structure of PAM is shown in Scheme 1. Because we used the same synthetic
procedure for all the C12-MMT/PAM nanocomposites, we describe here only the
method employed to prepare 1 wt% C12-MMT/PAM. 2,5-Diaminotoluene (3.1 g,
0.016 mol), and C12-MMT (0.053 g) in ethanol (300 mL) were placed in a
500 mL three-necked flask. This mixture was stirred at 25
C for 5 h under a
nitrogen atmosphere. A solution of terephthaldicarboxyaldehyde (2.2 g,
0.016 mol) in 100 mL of ethanol was then added to this mixture, which was
stirred vigorously at 80
C for 12 h. The resulting polymer was thoroughly
washed with water and then with ethanol prior to drying at 60
C in a vacuum
21 Characterizations of Nanocomposites of Liquid Crystalline Polymers
585
(OBDT) Nanocomposites
Diethyl-2,5-dihexyloxyterephthalic acid was synthesized via a multistep route, and
4,4
0 -biphenol was purchased from Aldrich Chemical Co. The polyester-based poly
(oxybiphenyleneoxy-2,5-dihexyloxyterephthaloyl) (OBDT) nanocomposite was
prepared by in situ polycondensation of equivalent weights of diethyl-2,5dihexyloxyterephthaloyl chloride and 4,4
0 -biphenol in the presence of C18-MMT.
Because the synthetic procedures for the C18-MMT/OBDT nanocomposites with
various organoclay contents are very similar, only the preparation of the 3 wt%
C18-MMT/OBDT is described here. TCE/pyridine (v/v = 50/50) (100 mL)
mixed solvent and C18-MMT (0.45 g) were placed in a polymerization tube, and
the mixture was stirred for 24 h at room temperature. Diethyl-2,5-dihexyloxyterephthaloyl chloride was obtained from diethyl-2,5-dihexyloxyterephthalic
acid and SOCl 2 following a method in the literature. Diethyl-2,5dihexyloxyterephthalic acid (20.0 g, 5.4 Â 10
À1 mol) was dissolved in SOCl 2 , and
the solution was refluxed for 12 h, after which the excess SOCl 2 was removed by
distillation at room temperature under vacuum. In a separate tube, 10.85 g (27 mmol)
of diethyl-2,5-dihexyloxyterephthaloyl chloride was added to TCE (100 mL), and
this mixture was added to the organoclay/pyridine solution and 5.1 g (27 mmol) of
4,4
0 -biphenol/pyridine solution, with vigorous stirring to obtain a homogeneously
dispersed system. This mixture was heated for 10 h at 100
C under a steady stream
of N 2 gas. The product was cooled to room temperature and poured into methanol.
The precipitated product was repeatedly washed with methanol and water, and dried
under vacuum at 80
C for 12 h to obtain the polyester-based OBDT nanocomposites. The chemical structure of OBDT is shown in Scheme 1. The synthetic
route for OBDT nanocomposite is shown in Scheme 3.
The polymers are soluble in mixed solvents; therefore, the solvent mixture
p-chlorophenol/TCE (w/w = 50/50) was used in the solution viscosity measurement.
The solution viscosity values (see Table 2) were found to range from 0.55 to 0.82.
These viscosity numbers can be regarded as constant except for that for the 7 wt%
C18-MMT/OBDT hybrid. In this hybrid, excess organoclay seems to prohibit
production of the higher-molecular-weight polymer.
Preparation of Polyazomethine (PAM) Nanocomposites
PAM was prepared by direct polycondensation of equivalent weights of
2,5-diaminotoluene and terephthaldicarboxyaldehyde in ethanol. The chemical
structure of PAM is shown in Scheme 1. Because we used the same synthetic
procedure for all the C12-MMT/PAM nanocomposites, we describe here only the
method employed to prepare 1 wt% C12-MMT/PAM. 2,5-Diaminotoluene (3.1 g,
0.016 mol), and C12-MMT (0.053 g) in ethanol (300 mL) were placed in a
500 mL three-necked flask. This mixture was stirred at 25
C for 5 h under a
nitrogen atmosphere. A solution of terephthaldicarboxyaldehyde (2.2 g,
0.016 mol) in 100 mL of ethanol was then added to this mixture, which was
stirred vigorously at 80
C for 12 h. The resulting polymer was thoroughly
washed with water and then with ethanol prior to drying at 60
C in a vacuum
21 Characterizations of Nanocomposites of Liquid Crystalline Polymers
585