Synthesis of poly(urethane)s based on diphenyl-silane/germane and oxyphenyl units: Structure-properties relationship

A series of poly(urethane)s (PUs) based on diphenyl-silane or -germane and oxyphenyl units were synthesized by polycondesation of 4-[4-[9-[4-(4- aminophenoxy)-3-methyl-phenyl]fluoren-9-yl]-2-methyl-phenoxy]aniline (3) and four bis(chloroformate)s (I-IV). These monomers were prepared and characterized in previous works. The best conditions for the polymerization reactions were investigated by a kinetic study. Also, a selection of the best solvent for the reaction was developed. Polymers were characterized by IR and ¹H, ¹³C, and ²⁹Si-NMR spectroscopy and the results were in agreement with the proposed structures. Poly(urethane)s showed inherent viscosity values between 0.12 and 0.31 dL/g, indicative of low molecular weight species, probably of oligomeric nature. The glass transition temperature (T _g) values were observed in the 127-168°C range by DSC analysis. Thermal decomposition temperature (TDT _10%) values were above 300°C. All PUs showed good transparency in the visible region (>80% at 350 nm) due to the incorporation of the bulky monomer (fluorene) and oxyether linkages.