Synthesis and characterization of new poly(amide)s derived from bis(4-(4-aminophenoxy)phenyl)methylphenylsilane and bis(4-carboxyphenyl)R1R2 silane acids

This study describes the synthesis and characterization of a new diamine; bis(4-(4-aminophenoxy)phenyl)methylphenylsilane, which by reaction with bis(4-carboxyphenyl)R1R2 silane derivatives, and following the methodology of the direct polycondensation, allowed the preparation of three new poly(amide)s (PAs). These polymers contain two diphenylsilane (Ph–Si–Ph) and oxyether moieties in their repetitive unit. The reaction to obtain the diamine starting from the respective diphenol was developed in two steps. The first step consisted on obtaining the dinitro derivative, bis(4-(4-nitrophenoxy)phenyl)methylphenylsilane, with a yield of 83 %. Then, this compound was reduced by reaction with hydrazine and Pd-activated carbon, with a yield of 67 % in the diamine. Both compounds were characterized by spectroscopic techniques (FT-IR, 1H, 13C and 29Si NMR). The synthesis of the PAs (PA-I, PA-II and PA-III) presented a yield of 35–79 %, glass transition temperature between 136 and 149 °C and inherent viscosities in the range 0.08–0.16 g/dL. PA-I and PA-III presented a transmittance value (at 400 nm) of 91 and 87 %, respectively, while PA-II only reached a value of 70 %. All these results were analysed in accordance with structural details of each repetitive unit and were also compared with those obtained from poly(amides) series not containing flexible elements in their chains. The TGA analyses demonstrated that the new polymers still maintain a high thermal resistance, despite the incorporation of the flexible units.