The Influence of Conformational Parameters on Some Physical Properties of Polyamides Containing Pendant Acetoxybenzamide Groups

Abstract

344* Conformational parameters of some aromatic polyamides containing pendant acetoxybenzamide groups have been calculated by Monte Carlo method taking into consideration the hindered rotation produced by the side groups. Several physical properties such as solubility, glass transition temperature, initial decomposition temperature and dielectric constant were studied with regard to the rigidity of the chain of these polyamides. It has been shown that glass transition temperature is correlated with chain rigidity, whereas initial decomposition temperature and dielectric constant are not.+7 ,83* Aromatic polyamides, pendant acetoxybenzamide, conformational parameters 41 !"#14! Aromatic polyamides are among the oldest members of the class of thermally stable polymers and have many technological applications [1,2]. Their structure can be modified in order to change their properties and render them suitable for special applications. Wholly aromatic polyamides are polymers with high thermal stability, chemical resistance and good mechanical properties [3]. However, their high glass transition temperature (1 2 ) and limited solubility in organic solvents make their processability quite difficult. To overcome these drawbacks to some degree an attractive synthetic approach to improving the solubility and processability is the incorporation of bulky substituents such as pendent groups along the polymer backbone. In this way it is possible to obtain good solubility without sacrificing the thermal and mechanical properties to a great extent. Many authors

Structural aspects in polymers: interconnections between conformational parameters of the polymers with their physical properties

“…We tried to link the Kuhn segments obtained for polyheteroarylenes to some physical properties such as glass transition temperatures T g , moduli of elasticity, refractoriness parameters of flammability, and others [23][24][25][26][27][28][29][30][31][32][33][34][35].…”

Synthesis and characterization of new aromatic copoly(ether amide)s bearing 4-trifluoromethylphenyl-2,6-diphenylpyridyl moieties in the main chain

“…To overcome these limitations, a lot of efforts have been made to prepare soluble or thermoplastic polyamides without obviously lowering the high thermal and mechanical properties. Some approaches such as introducing flexible linkages, [3][4][5] bulky pendent groups, [6][7][8][9] cardo units, [10][11][12][13][14] heterocycles rings, [15][16][17] asymmetry or noncoplanar structures [18][19][20] into the polymer backbone are valuable in improving the solubility. Among them, incorporation of fluoroalkyl groups, especially 4-trifluoromethyl, has been demonstrated to afford polyamides with desirable solubility, thermal stability, dielectric, and optical properties.…”

New fluorinated poly(pyridine amide)s derived from 2,6-bis(4-iodophenyl)-4-(4-trifluoromethylphenyl)pyridine by C–N coupling reaction

“…[8][9][10][11] Fabrication of most polyamides, However, is extremely difficult because of their high melting or softening temperatures and their limited solubility in organic solvents. So, numerous attempts have been centered on improving their processability and solubility through the introduction of flexible linkages, [12][13][14][15][16] asymmetry or noncoplanar units [17][18][19][20] and bulky substituents such as acetoxybenzamido, 21 triphenyl, 22 4-methoxy-2-pentadecylphenylcarbamoyl, 23 trifluoroacetamido 24 and trifluoromethyl [25][26][27][28][29] into the rigid polymer backbones. On the other hand, it has been demonstrated that the polyamides containing pyridine heterocyclic units in the main chain possess excellent thermal stability and mechanical property at elevated temperature due to the symmetry and aromaticity of the pyridine ring, as well as the polarization of nitrogen atom in pyridine.…”