Mechanically and thermally stable blends of poly(styrene-butadiene-styrene) with conducting poly(thiourea-azo-naphthyl)

Abstract

A new aromatic azo-polymer, poly(thiourea-azo-naphthyl) (PTAN), has been synthesized using 1-(5-thiocarbamoylaminonaphthyl)thiourea and diazonium salt solution of 2,6-diaminopyridine. PTAN was easily processable using polar solvents and had high molar mass 57 × 103 g/mol. Electrically conducting, mechanically and thermally stable rubbery blends of poly(styrene-butadiene-styrene) (SBS) triblock copolymer and PTAN were produced by solution blending technique. FESEM of SBS/PTAN blends revealed nano-scale dispersion of the conducting filler showing good adhesion between the matrix and PTAN. Remarkable effects of azo-content on the conductivity of SBS-based blends have been observed. Accordingly, PTAN loading from 10 to 60 wt% increased the conductivity from 1.24 to 1.66 S/cm. Relationship between PTAN loading and thermal stability of the materials was also investigated. With increasing the PTAN content, 10% gravimetric loss was increased from 484 to 500 °C, while glass transition was enhanced from 119 to 126 °C. Thermal and conducting data of the blend showed better results relative to pure elastomer but were lower than those of the conducting filler. Similarly, the tensile strength (57.35–62.33 MPa) of SBS/PTAN was improved relative to there of SBS. Fine balance of properties renders new materials fairly better than the existing elastomeric blends used in a number of applications.