Homo‐ and Co‐Polymers of Norbornene Containing Aryl‐ and Hetaryl‐Azo Dyes; Synthesis and Sensing Properties

Abstract

A series of polynorbornene homo‐ and copolymers containing aryl‐ and/or hetaryl‐azo dyes were prepared through ring‐opening metathesis polymerization (ROMP). Thermal studies indicated that the polymers were thermally stable up to 250 °C, and possessed glass transition temperatures ranging from 93 to 133 °C. In THF solutions, the aryl‐azo dye containing homopolymers, displayed λmax = 417 nm while the hetaryl‐azo dye containing homopolymers displayed λmax = 495 nm. The copolymers displayed a λmax that encompassed both the aryl‐ and hetaryl‐azo dye range. The monomers and polymers showed bathochromic shifts in solution when acidified. The polymers were cast into films that changed colour in the presence of both aqueous 1.2 M HCl or HCl(g). The colour change reverses when exposed to aqueous 1.2 M NaOH or NH3(g). This process was repeated several times without disintegration of the polymer film, indicating that these polymers may be useful as reusable acid sensors.

Dye-functionalized polymers via ring opening metathesis polymerization: principal routes and applications

“…As opposed to radical polymerization techniques, ROMP is a facile way to incorporate these units into polymers and therefore, a number of polynorbornenes with azo dyes (5) have been synthesized [48][49][50][51][52]. In Fig.…”

“…A wide range of suitable monomers has been copolymerized comprising (hetero)polyaromatic compounds [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], and more sophisticated functionalities like conjugated oligomers [34][35][36][37][38][39], triphenylmethane [40][41][42][43][44][45][46][47], azo [48][49][50][51][52], or polymethine [53][54][55][56][57] dyes. Even transition metal coordination compounds of aluminum [58,59], iron [60], zinc [61][62][63], ruthenium [64, 65], europium …”

Design of Organoiron Macromolecules Based on Upper Rim Functionalized Calix[4]arenes

“…This behaviour was also observed for solution-phase acids. We have previously shown that azo dye polymers show potential as solid-state acid sensors, [32] this behaviour was also observed for compound 10. A solid sample of this complex was also exposed to HCl (g) and was observed to change to a deep purple colour; when exposed to NH 3(g) the purple colour changed back to orange which indicated that the azonium ion could be formed in the solid state.…”

Synthesis of Upper Rim Functionalized Calixarene‐Based Poly(norbornenes)

“…The difference in thermal stability is due to the presence of the azo dye in polymers 19 and 20, since the azo group has been found to decompose at temperatures around 200 8C. [24] DSC showed that the polymers possessed glass transition temperatures (T g ) between 35 8C and 103 8C ( Table 2). As can be seen, the phenol containing polymers 18 and 20 possess higher T g s than polymers 17 and 19.…”

“…Previously we have shown that poly(norbornenes) containing azo dyes show potential for solid state pH sensors. [24] Polymers 19 and 20 were tested for visual identification of acid in the solid state. As solids, polymers 19 and 20 appeared as orange to reddish orange materials, but when exposed to HCl (g) the materials became purple in colour.…”