Synthesis of 2-{5-[4-((4-nitrophenyl)diazenyl)phenyl]-1,3,4-oxadiazol-2-ylthio}ethyl acrylate monomer and its application in a dual pH and temperature responsive soluble polymeric sensor

Figures & data

Figure 1. Structure of the copolymer.

Figure 2. The FT-IR spectra of (a) copolymer and (b) NDPOE-acrylate.

Figure 3. ¹H NMR of copolymer.

Table 1. The size and size distribution of copolymer particles dispersed in water at different temperatures.

Temperature (°C)	17	20	25	28	30	32	34	36	40
Z average (d nm)	500	555	770	700	792	622	476	386	202

Figure 4. Particle size distribution profiles of copolymer in water at 28–34 °C.

Figure 5. The UV–vis of NDPOE-acrylate (0.175 mM) in various solvents at room temperature.

Figure 6. UV–vis of copolymer (0.65 mg/mL) at different pH at 20 °C.

Figure 7. The LCST transition curves of copolymer at pH 2 and 4 values.

Figure 8. Hydrogen bond between nitrogen atoms of oxadiazole and protonated diazenyl moiety in acidic media.

Figure 9. The radar-type plot of absorbance of the copolymer (0.65 mg/mL) at different pH values as function of temperature in λ_max = 392.

Figure 10. The fluorescent spectra of NDPOE-acrylate (1 mM) in different solvent (λ_ex = 342 nm).

Figure 11. Fluorescence intensity of copolymer (0.65 mg/mL) at different pH values as function of temperature; λ_ex = 483 nm, λ_em = 520 nm.

Scheme 1. Synthesis of NDPOE-acrylate.